CN103733087B - Selectivity distance range imaging - Google Patents
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Abstract
A kind of method of distance using Modulation and Amplitude Modulation continuous wave scope imaging device to determine object, including launching modulation illumination sign.By pseudo noise code, described modulation illumination sign is modulated.Modulation image sensor is carried out, to catch multiple samples of the modulation illumination sign from object reflection based on pseudo noise code.Determine the phase shift between multiple sample and modulation illumination sign.
Description
Technical field
The present invention relates generally to brightness and the degree of depth/scope (range) detection, and more particularly, to for selectivity
The method and apparatus of scope imaging.
Background technology
Scope imaging system, also referred to as scope camera, scope image camera or range finding (ranging) device, determine and want
The distance of the object in the scene of imaging and brightness.The scope image camera of a kind of general type uses Modulation and Amplitude Modulation continuous wave
(" AMCW ") technology.
As detailed below, the scope image camera of AMCW technology is used generally to use light source to launch intensification modulation illumination
Signal, to be illuminated the scene wanting imaging.Then by the object in scene, signaling reflex returned scope image camera.Then
Multiple images of reflection light are caught by the special sensor chip of such as CMOS.Then use processor by the plurality of
Image compares each other and the intensity modulated illumination sign of the plurality of image with transmitting is compared, so that it is determined that light
Intensification modulation in phase transformation.Then analyze phase transformation, to determine the distance between object and scope image camera, also determine that scene
The size of middle object, shape and position.So, at such as automotive safety and control system, multimedia user interface and image
In many different application of segmentation and surface scan cutting, scope image camera is highly useful.
Between scope image camera and the object wanting imaging, effectively determine that scope depends on intensification modulation illumination sign
And the phase contrast between the signal received.Because generally carrying out modulation image sensor by illumination sign, along with light is from scope imaging
Camera leaves, and described light starts to become the modulation out-phase with imageing sensor.So, the distance of light process is the shortest, and light is the most same
Phase.In other words, the light from the object reflection close to scope image camera has the modulation with scope image camera close to same
The intensification modulation of phase, and the light of object reflection from afar has and the intensification modulation of scope image camera out-phase.Generally make
Both, in the case of having modulated illumination sign also modulation image sensor with same signal, different letters can be used in some cases
Number reach similar result.
For digital photograph, the image of seizure is generally formed by pel array, and the object efficient mapping in scene arrives
On pel array.Unlike common digital image, scope image camera the pixel caught not only records the object from scene
The brightness of illumination (can include color) of the light of reflection, also records the phase place of modulation envelope.Therefore, each in the image of seizure
Pixel will have phase component based on the light being returned described pixel by the object reflection in scene.And, corresponding to the most not
The pixel of the scene areas with object will not receive the signal of reflection, but only receives ambient light or from other sources (the most too
Sun) light of the light that reflects or multipath modulation (causes other object reflection of undesired interference signal out from scene
Launch light).Common scope image camera sensor includes that background or DC suppression circuit, this background or DC suppression circuit allow more
The dynamic range being efficiently used sensor modulates light for catching, so, bias light can effectively be ignored by sensor.
In the case of having the multiple method realizing common scope image camera, it is provided that Fig. 1 is to illustrate one so
The simplification view of scope image camera.As it is shown in figure 1, common AMCW scope image camera 100 can include for wanting
The scene of imaging launches the advertiser 101 of intensification modulation illumination sign, such as laser diode or light emitting diode, also includes
For using the object reflection from scene to return the partial transmitting signal of system 100 to catch the imageing sensor 102 of image.So
The image of the object of transmitting with seizure is compared by preprocessor 103, to determine the brightness of each pixel in the image of seizure
And phase shift.By doing so it is possible, processor can determine the distance from system 100 of the object in scene.System 100 includes alternatively
To the input equipment 104 of control system 100, display 105 and memorizer 106, or described device 104,105 and 106 are permissible
It it is the form of the separate computer system connected by interface cable.Can be from any known device performing described function
Select these devices.There is many known modulated signal devices 101 and the method for imageing sensor 103.Such as, signal sends
Device can be only the light source the most quickly opened and closed, and imageing sensor 102 can use high-speed shutter or logical
Gain or the sensitivity of crossing control imageing sensor are modulated.Processor 103 can also include signal generator, or similar dress
Put, to help modulated signal device 101 and imageing sensor 102.However, it is also possible to signal generator is provided separately.
Fig. 2 shows the simplification functional diagram of above-mentioned critical field image camera described in reference diagram 1.As in figure 2 it is shown, from letter
The intensification modulation envelope of the illumination sign that number device 101 is launched is shown as sine wave shape, but is generally also modulated into square wave.So
After each object 21,22 and 23 reflected signal in the scene being just imaged.As in figure 2 it is shown, be reflected back imageing sensor 102
Light will be through different distances according to the relative distance of object 21,22 and 23 of reflection light.This will result in the light of reception
Modulate distance based on process and there is different phase places.Although being shown without in Fig. 2, but the amplitude of waveform also can be according to process
Distance and the surface scattering attribute of object and change.
Figure 11 shows the schematic diagram of the element for providing known scope sensing system.Although the schematic shows
For the shutter of modulation image sensor, it should be noted that the various sensors of shutter can be used without using for this.
Such as in United States Patent (USP) No.7,541,255, United States Patent (USP) No.7 of Dorrington of Billmers et al.,
391,505, in United States Patent (USP) No.5,534,993 of United States Patent (USP) No.5,835,199 of Phillips et al. and Ball et al.
Disclosing the method for signal measurement, all these patents are as with reference to being herein incorporated by entirety.And, see
The international publication number No.2006/031130 of international publication number No.2004/090568, Carnegie et al. of Dorrington and
The international publication number No.2009/051499 of Payne et al., all these patents are as with reference to being herein incorporated by entirety.
But, traditional scope image camera shows poorly in some conditions.Such as, when traditional scope imaging
When air between camera and the object wanting imaging is not known, such as when having mist or cigarette when, or by glass or
In the case of plastic window carries out imaging, traditional scope image camera may not accurately determine object away from
From.Especially, the granule suspended in air or chip, may result in the illumination sign one from traditional scope image camera
Part is reflected back, and then this may result in distance and determines inaccurate.
Summary of the invention
Embodiments of the present invention relate to a kind of in the optional distance from Modulation and Amplitude Modulation continuous wave scope imaging device
The method and apparatus that place carries out imaging to object.The method includes launching modulation illumination sign, (or is combined with by pseudo noise code
The continuous wave of pseudo noise code) described modulation illumination sign is carried out intensification modulation；At imageing sensor, receive described modulation shine
The reflection of clear signal；Catch multiple samples of the modulation illumination sign of reflection, wherein use described pseudo noise code to modulate sampling；
Determine the phase shift between the modulation illumination sign of transmitting and multiple sample or time delay, to determine at least one phase shift or time delay；With
And based on a determination that phase shift or time delay determine the scope between described device and at least one object.
By illuminating and the speed of pseudo noise code of sampling and relative time determine and selected object detected wherein
Region or window.Use the method, it is possible to ensure that range unit only carries out imaging to the object in imaging window.The method also may be used
To include signal bias and noise and multipath interference are compensated.
The other aspect of this method can include making sample modulation code time delay, to determine imaging window, thus based on prolonging
Time determine the distance between device and imaging window.Use the method, the position of imaging window in scene can be adjusted in real time
Put.
According to the additive method of the present invention, in the optional distance from Modulation and Amplitude Modulation continuous wave scope imaging device to object
The further aspect carrying out imaging may include that transmitting modulation illumination sign, by pseudo noise code to described modulation illumination sign
Carry out intensification modulation；The reflection of described modulation illumination sign is received at imageing sensor；Catch the modulation illumination sign of reflection
Multiple samples, wherein use described pseudo noise code transfer system sampling；And adjust the operation frequency of described pseudo noise code, come really
Determining imaging window, wherein range unit only carries out imaging to the object in described imaging window.Can be based on described pseudo noise code
Operation frequency determine the distance between the leading edge of imaging window and back edge.
Modulation and Amplitude Modulation continuous wave scope imaging device according to the present invention may include that illuminator, this illuminator quilt
It is configured to launch modulation illumination sign, wherein by pseudo noise code, described modulation illumination sign is carried out intensification modulation；Image sensing
Device, this imageing sensor is for receiving the reflection of described modulation illumination sign, and this imageing sensor is configured to catch reflection
Multiple samples of modulation illumination sign, wherein use described pscudo-random codc modulation to sample；And processor, this processor is for really
Phase shift between fixed modulation illumination sign and the multiple sample launched, so that it is determined that at least one phase shift, and relative to modulation
The modulation of illumination sign carries out time delay to the modulation of sampling.
It addition, the phase in-migration that processor is configured to determine determines the model between device and at least one object
Enclose.And, illuminator may be configured to launch continuously intensification modulation illumination sign when imageing sensor is sampled.Processor
Can be configured to adjust the clock cycle of described modulation illumination sign.Furthermore, it is possible to adjust substantially in real time relative to
The modulation of modulation illumination sign carries out the length of time delay to the modulation of sampling.
Modulation and Amplitude Modulation continuous wave scope imaging device can be in conjunction with the modulation to sampling of the modulation about modulation illumination sign
Carry out the length of time delay, motion based on the object being just imaged can adjust described modulation illumination sign substantially in real time.
Described device may be configured to only carry out the object in imaging window imaging, wherein said imaging window have leading edge and
Back edge, and generally triangular in cross-sectional shape.Described device can also include frequency regulator, and this frequency regulator is used for adjusting puppet
The operation frequency of random code.Furthermore it is possible to operation frequency based on pseudo noise code determines imaging window.
For using Modulation and Amplitude Modulation continuous wave scope imaging device to determine another exemplary side of distance of object
Method includes launching modulation illumination sign.Described modulation illumination sign is modulated by pseudo noise code.Adjust based on described pseudo noise code
Imaged sensor, for multiple samples of the modulation illumination sign caught from described object reflection.Determine the plurality of sample
Phase shift between this and described modulation illumination sign.
Accompanying drawing explanation
Fig. 1 shows the schematic diagram of standard imager；
Fig. 2 shows the functional diagram of standard imager；
Fig. 3 shows the schematic diagram of imaging device according to an illustrative embodiment of the invention；
Fig. 4 shows the example of pseudo noise code；
Fig. 5 a shows the mixing of two synchronizing signals；
Fig. 5 b shows and the mixing of two signals synchronize differing 90 °；
Fig. 5 c shows and the mixing of two signals synchronize differing 180 °；
Fig. 5 d shows two mixing synchronizing square wave；
Fig. 5 e shows and the mixing of two square waves synchronize differing 90 °；
Fig. 5 f shows and the mixing of two square waves synchronize differing 180 °；
Fig. 6 a shows the mixing of the signal using the pscudo-random codc modulation synchronized；
Fig. 6 b shows the mixing of the signal of the pscudo-random codc modulation using partial asynchronous；
Fig. 6 c shows the mixing of the signal using asynchronous pscudo-random codc modulation；
Fig. 7 a shows when the modulation of imageing sensor not being added time delay, uses the exemplary enforcement according to the present invention
One illustrative embodiments of the imaging window that the imaging device of mode creates；
Fig. 7 b shows when the modulation of imageing sensor is added time delay, uses the exemplary embodiment party according to the present invention
One illustrative embodiments of the imaging window that the imaging device of formula creates；
Fig. 8 a shows the triangular nature of the imaging window created according to an illustrative embodiment of the invention；
Fig. 8 b shows the triangular nature of the imaging window created according to an illustrative embodiment of the invention, Qi Zhongtong
Cross increase modulating frequency to shorten the degree of depth of image window；
Fig. 8 c shows the triangular nature of the imaging window created according to an illustrative embodiment of the invention, Qi Zhongtong
Cross increase modulating frequency to lengthen the degree of depth of image window；
Fig. 9 shows and uses known imaging device by the dirty window result to exemplary scenario imaging；
Figure 10 shows that the imaging device using the illustrative embodiments combining the present invention is by dirty (dirty) window
Result to the exemplary scenario imaging of Fig. 9；
Figure 11 shows the schematic views of the assembly for providing known scope sensing system.
Detailed description of the invention
In the following description of the illustrative embodiments to the present invention, with reference to the accompanying drawings, pass through in the drawing
The mode illustrated shows embodiments of the present invention.It should be understood that under the premise without departing from the spirit and scope of the present invention,
Other embodiments can be used and the change in structure can be made.
As it has been described above, traditional scope image camera shows poorly in some operating conditions.Such as, when scope imaging
When air between camera and the object wanting imaging is unintelligible, scope image camera may not accurately determine distance.This is not
Accuracy is the illumination being reflected back scope image camera by part from the aerial granule of suspension, chip or glass or plastic window
Signal section causes.As it has been described above, multiple images of the image capture sensor scene of scope image camera.These images will
Represented by the pixel both there is luminance component also having phase component.Under normal operation, scope image camera is reflected back into
With concentrating signal on single pixel, only there is single phase component.This is because all modulated signals incided in pixel
All from single object reflection.At the environment that some are other, in the case of light can incide in pixel, light is not modulated and can
To be responsible for by processor.But, when the air between scope image camera and object is suspended with granule, it may be possible to have
Mist, cigarette or the situation of dirty window, some modulation illumination signs were reflected back toward scope before reaching the object being just imaged
Image camera.This causes pixel to catch the modulation illumination sign with different phase components.Existing scope image camera is not
Can determine which phase component is relevant with object, which is relevant with atmospheric dust.It addition, air particles may make modulation illumination letter
Number scattering, thus causes the impact of the reflected signal of multiple pixel.Fig. 9 shows by the path being positioned at illumination sign
The example of the image of " dirty " window impact.As it is shown in figure 9, due to unwanted reflection and light scattering, the scope imaging of standard
Camera can not correctly determine the distance of the various piece of the object of imaging.
Similarly, there is the emerging application that AMCW scope image camera known to some is the most particularly suitable.Develop new
Computer control system, it depends on scope image camera to determine when that user makes for controlling computer system
Some action (such as gesture).These new application many are currently used for game machine and are used for controlling personal computer.When with
When family is isolated, such as, when user is individually before firm background (such as wall), current scope image camera is permissible
It is used together with these systems.But, when there is the position of movable generation in user face behind, current scope image camera exists
Determine whether the user in background or people make in gesture possible relatively difficult.Because the image of common scope image camera
The sensor all distances before scope image camera collect the light from object reflection, so current scope image camera
There is difficulty.Thus, object or people " are seen " in scope image camera meeting, no matter object or people from scope image camera away from
From how, as long as no other objects between object and scope image camera.Although background sometimes can be corrected
Motion, but owing to having other people near (such as in game environment), it is generally difficult to correct.
These systems are likely to be positioned at from (the intensification modulation illumination reflected here of scope image camera position farther out
Signal phase differs by more than 360 °) object motion fascination.When this occurs, scope image camera may be by non-
The intercept of Chang Yuan becomes a lot of close to scope image camera.In the system that other are emerging, such as Vehicle security system, also deposit
In these same difficulties.New Vehicle security system begins to use scope image camera to determine the close of the vehicle of motion.
Then near controlling such as constant speed manipulator or the function of brake hard determined by using.
The difficulty relevant to part opaque medium is opaque to scope imaging device.Known in photography under water
There is similar situation.Catching image under water may be more difficult, because that water typically obscures or dirt.Dirty water (class
It is similar to mist) light scattering can be made to obtain very serious thus stop picture catching.Under water photography in use a scheme be referred to as " away from
From gated imaging ".Range-gated Imager carrys out work, with to scene lighting by using flash of light at a high speed.Then in flash of light and scope
The time delay of careful timing is added between the triggering of the shutter of image camera.Due to this time delay, near Range-gated Imager camera
The light of fuzzy water reflection be not imaged, this is because it has returned to scope image camera before the shutter is triggered.Favorably
Ground, then, is caught in from the light of the object reflection being positioned at away from from Range-gated Imager camera at least preset distance, this is because
When these light return to scope image camera, shutter is timed and opens.Similarly, do not catch from the object exceeding certain distance
The light of reflection, this is because the shutter close of scope image camera before light returns to Range-gated Imager camera.Can lead to
Cross adjust time delay and shutter and flashing speed come regulating object be imaged the distance of process.Although some form of distance choosing
Circulation method can effectively overcome this problem, but the time domain method used in underwater photography can not become with based on scope ideally
The AMCW of picture is compatible, during this is because AMCW based on scope imaging uses the image integration that scene extends illumination and prolongation
Between, thus collect much more light, to generate the image with the signal to noise ratio significantly improved；Thus reach ratio pulse gate method
Preferably certainty of measurement.
In an exemplary embodiment of the present invention embodiment, pseudo noise code is used to overcome lacking of traditional scope image camera
Fall into.As will be described in detail below, the pseudo noise code illumination sign to launching and imageing sensor is used to be modulated, with right
Part opaque medium (all air if any mist) and background and foreground object or people are compensated.And, use pseudorandom
Code allows definition imaging window so that the Object identifying in scope imaging window is only want imaging right by scope image camera
As.Sensor is tuned, to identify specific illumination code pattern and timing.The signal of the object reflection outside imaging window
The pattern with tuning does not matches, but is calculated average by image integration process, and is identified as constant background illumination, permissible
Use any of technology that this constant background illumination is compensated.As described further below, it is possible to according to system
Demand dynamically adjust position and the size of imaging window.
In this illustrative embodiments, use pseudo noise code to modulate illumination sign before transmission, use same puppet
Random code carrys out modulation image sensor.When signal object reflection from afar returns scope image camera, processor can be based on
The signal of the constructive interference (constructive interference) reflection to being modulation illumination sign is isolated.
By the way of simple declaration, contribute to imagining two sines with same frequency and amplitude shown in Fig. 5 a
The situation that ripple mixes.When ripple synchronizes, a type of constructive interference occurs, and mixes the ripple causing bigger amplitude
Shape, is averaged to the actual value after integration, as indicated by the shadow region below the mixed signal produced.On the contrary, ripple is worked as
During with Tong Bu difference 90 °, the mixing of signal causes following waveform, and the integrated value that wherein part signal has reduces, such as Fig. 5 b institute
Show.It addition, when ripple is with Tong Bu difference 180 °, the mixing of signal causes the signal of relatively short arc, as shown in Figure 5 c.Fig. 5 d, 5e
Respectively describe and the mixing of the square wave synchronize differing 0 °, 90 ° and 180 ° with 5f.When to the pscudo-random codc modulation using synchronization
Signal when applying this principle of uniformity, similar result can be produced, as shown in Figure 6 a.It is, when the signal of transmission is mixed with
During the demodulated signal modulated equally, signal is synchronized, and exists and maximum related value can be caused to do with the long mutually of maximum integrated signal value
Relate to.
But, when signal starts to become asynchronous, signal quickly discharges cohesiveness and its correlation.Fig. 6 b shows puppet
Random code has just begun to change into asynchronous example, and Fig. 6 c shows the example of the entirely different step of pseudo noise code.The noise produced
Actually with by two signals using different code modulation are mixed noise mutually that generate can not be distinguished.Thus, formerly
In the application of front use pseudo noise code, all effort made are provided to make signal keep synchronizing.But, when entering suitably
When row controls, this desynchronizes and can bring previous unconsummated effect.By using pseudo noise code carefully to modulate relevant signal,
While fuzzy air or other objects are compensated (or ignoring), it is possible to " frequency domain " method of use creates imaging window
Mouthful, this imaging window allows imaging device only to the object imaging in imaging window.
Such as, when to modulating illumination sign from scope image camera transmitting and the image of same scope image camera being passed
During sensor application pseudo noise code, if sequence be synchronize, scope image camera by can to reflection picture decoding.But,
When two pseudo-random sequences lose synchronization, signal cannot be decoded.Accordingly, because signal is only through shorter distance,
And be returned the most at once thus keep synchronizing, so keeping synchronizing from neighbouring object reflection signal out.On the contrary
Ground, returns to scope image camera from the time being positioned at from imaging device object reflection farther out signal demand out is longer,
Thus become the most asynchronous.Therefore, will not be to the object imaging outside particular range.It practice, imaging window provides
Its outside signal and the uncared-for space of object.Fig. 7 a shows such a example.As shown in Figure 7a, from exemplary
The light that scope imaging device 100 is launched is reflected back to device 100 from object 701 and 702.If launch signal become with
The asynchronous ultimate range can passed through before of modulation of imageing sensor is 2 Δs, then the leading edge of imaging window will be at dress
Put the surface of 100, and the back edge of imaging window will with device distance, delta at.Therefore, it will to from from device 100 away from
The imaging suitably of signal out of object reflection in Δ, and farther object will effectively be ignored.As shown in Figure 7a, exist
The first object 701 at distance alpha will be imaged, and the second object 702 at distance beta will not be imaged.
" ignore " it should be appreciated that nonsynchronous reflected signal actually need not be imaged device.But, amass at image
After/, described signal can be translated into DC signal.DC signal may offset and noise level by Enabling Signal, it is possible to use tool
There is the imageing sensor of extraordinary " DC shift suppression " to compensate described signal bias and noise.
Above-mentioned example is helpful on more remote object ignoring, but has certain limitation: it is only capable of right
Object in scope imaging device carries out imaging, this is because when using synchronization pseudo noise code to come modulation illumination
Signal (transmitting signal) and time imageing sensor is modulated, the leading edge of imaging window will be close to imageing sensor.One
In the case of Xie, this is probably enough, such as when combining games system to use imaging system, is wherein positioned at before device
User can attempt to use gesture recognition system to control game, or wherein user attempts to use gesture recognition system to control
TV.But, usual user is not unique people or object in room.Such as, may have in room other people or
(include in the background) having object in the scene.This is the most undesirable.When wanting the object of imaging from range unit away from some
Time, the leading edge of imaging window is set to close to object and from sensor farther out so that the impact of mist or cigarette is minimum
It is favourable.Similarly, undesired object is generally than wanting the object of imaging close to range unit or farther out.Such as, as
Fruit is in figure 7 a, it is desirable to the second object 702 imaging rather than to the first object 701 imaging, then need scope image camera
100 move close to the second object 702.This is not the most attainable.Pitch-dark safe glass is ensconced at scope image camera
Also the difficulty being similar in the case of after glass, this is because may be with the side similar with mist from the reflection of glass inner side
Formula can introduce error.
In an illustrative embodiments, to imageing sensor modulation add time delay, with by imaging window away from one-tenth
As device moves.By changing time delay, the position adjustment of imaging window can be become from the specific position of device, have this its
The light being imaged the object reflection outside window is ignored on effect ground, also makes between scope image camera and object interested simultaneously
The impact of mist or other objects alleviates.This is probably useful in various applications.Such as, generally stand to become from scope user
As, in the game application of camera front 4 to 6 feet away, scope image camera can be configured to ignore from scope image camera relatively
Any object closely or farther out.It is similar to, is positioned in the application of scope image camera front 6 inch at safety glass, model
Enclose image camera and can be calibrated to ignore the signal of the object reflection in a feet of scope image camera.As separately
One example, when range image camera in vehicle restraint system, scope image camera can be set to only identify
From the object of scope image camera 5 to 500 feet away, thus eliminate the light reflected from the rain close to scope image camera or mist
And the light of other cars reflection outside region-of-interest.
Fig. 3 shows the example of imaging system 300, and wherein processor 303 includes that the pseudo noise code for generating code is raw
Grow up to be a useful person 307.Processor 303 can also include modulating part 308, the modulation illumination letter generated by advertiser 301 for modulation
Number, and for modulation image sensor 302.Time delay can also be incorporated in imageing sensor by system 300, thus by imaging window
Mouth moves away from imageing sensor 301.
Although Fig. 3 shows the system of simplification, it should be appreciated that, it is possible to use many various combinations of hardware and software
Carry out forming range imaging system.Such as, advertiser 301 and/or imageing sensor 302 can be at its exterior.And, pseudo-with
Machine code generator 307 and/or modulating part 308 can be outside processors 307, pseudorandom number generation device 307 and/or modulation portion
Points 308 and processor 307 can also be same device.
Fig. 7 b shows the scene similar with Fig. 7 a, but wherein user wishes, to the second object 702b imaging, to neglect simultaneously
Slightly the first object 702a and the 3rd object 703b.Furthermore, the effective depth of imaging window is distance, delta.It is, from modulation letter
Number point the most synchronize with imageing sensor starts, and modulated signal can be through distance 2 Δ, until it lose synchronization.At signal
Before becoming to synchronize, the distance of signal process can be adjusted by adjusting time delay.The most as shown in Figure 7b, imaging window is deep
Degree remains Δ.But, the edge nearest from device 100 of imaging window from device 100 away from d, and distal edge away from
Away from d+ Δ, wherein can determine distance d by the time delay of the modulation that adjustment is applied to imageing sensor.
As seen above, the depth delta of imaging window converts by reflected signal with between synchronizing and be asynchronous
Decoding signal obtains.Each pseudo-random sequence has specific correlation function.When ideally, marshalling reflected signal is conciliate
During code signal, measurement of correlation will be one.But, along with reflected signal and decoding signal start dislocation, dependency is reduced to zero.
This causes imaging window to have three angular correlation functions, as shown in the example in Fig. 8 a.The place neat at signal perfect rank goes out
The peak value of existing triangle, and along with signal wants marshalling dependency to be misplaced to reduce.Although this reduction can be generally
Linear, as hi the example shown, but according to the code used and response, bandwidth or illumination and the transfer letter of sensor modulation
This reduction of number is probably nonlinear.Because imaging window is to become more and more nonsynchronous reflection with the modulation of imaging sensor
The side-product of light, so imaging window is not likely to be the window being clearly defined.On the contrary, in some embodiments, window will
There is extraordinary center and the edge of rough definition of definition, synchronize to fade away to become random in edge.This causes
Most information is assembled from the center of window, and substantial amounts of information is assembled fewer and feweri towards leading edge and the back edge of window.Separately
Outward, although in Fig. 8 a, the shape of imaging window is illustrated as triangle, but this triangular representation is by the object of respective distance
Reflex to the data volume of device.Triangle does not indicates that the physical form of imaging window.
Although imaging window is shown as having triangle, it should be appreciated that, this shape is not necessarily.At this
In bright various embodiments, imaging window can have many different shapes, includes but not limited to, substantially triangle
Shape, cosine periodic shape, round-shaped or sinusoidal shape.Have generally triangular in cross-sectional shape shape image window can at one or
Many aspects are different from triangle, include but not limited to have round or limit unclear turning or have and limit unclear limit
Edge.
Sometimes, need to change the depth delta of window.Such as, when wanting the to liking " narrow " and special in air of imaging
Time foggy, the degree of depth of highly preferred imaging window as far as possible narrow, to avoid mist or to want object after the object of imaging
Negative effect.The depth delta of imaging window can be adjusted in a different manner.Such as, different pseudo noise codes will have wherein phase
The different correlation function that closing property reduces with different speed.It addition, the depth delta of imaging window will be with pseudo random clock frequency
It is inversely proportional to.And hence it is also possible to change depth delta by adjusting pseudorandom or clock rate.Fig. 8 b and 8c shows this adjustment
Example, depth delta is decreased or increased the most respectively.
It addition, use different time delays or modulating frequency, can be by two parts of pseudo noise codes or two or more codes
The most effectively it is added in integration period, for the degree of depth widening imaging window.Multiple code can be used to use two
Overlapping or separate image window replaces single triangle imaging window.Furthermore, it is possible to there is definition less by use
The pseudo noise code of good dependency increases the degree of depth of imaging window so that pseudo noise code no longer become to have dependency or
Become non-correlation.The bad code of this dependency is known with moving communicating field contrary to the use of pseudo noise code,
In moving communicating field, use the code of the extraordinary dependency with definition accurately to refuse other pseudorandoms as far as possible
Code.
According to an exemplary embodiment of the present invention, it is possible to make the degree of depth narrow thus in the mistake of single clock cycle
In journey, dependency drops to 0 it is, mono-clock cycle of Δ/2=from 1.Pseudo noise code used and frequency can be selected
Generate and have than triangle more like the imaging window of rectangular shape.By using rectangle imaging window, whole at window
The data of similar quantity can be collected in the degree of depth.This can obtain brightness more accurately and determine.
Furthermore it is possible to by pseudo noise code being mixed with continuous modulation signal, use existing range determining method.Can
To be used for performing a method of this married operation including, by pseudo-random sequence, continuous modulation signal is carried out binary phase volume
Code.This operation is realized by continuous modulation signal phase shift p radian is multiplied by pseudo noise code.The method for optimizing realizing this mixing is
Numeral XOR is also referred to as " XOR " function and is applied to continuous modulation and pseudo-random signal.
May then pass through collect receive signal multiple samples to determine object range, wherein in the phase of pseudo-random sequence
While position or offset stays constant, add phase offset to continuous modulation signal.In this embodiment, object range is permissible
It is encoded into the phase place of continuous modulation signal, and the amplitude of the continuous modulation signal that pseudo noise code is to recovering applies weight.This power
Heavily corresponding to the Range Imaging window selected, wherein the object in window has a biggest amplitude, and the object outside window
Amplitude is substantially zero.Then can calculate the phase place of continuous modulation signal according to multiple samples, thus provide scope to object.
In an illustrative embodiments, scope image camera can serve as the assembly in video conferencing system, in institute
State and video conference needs only convention goer is carried out imaging.By only participant being carried out imaging, can add to image
Other background data so that seem participant in different positions, and they are actually at the biggest meeting room
Or on working site.Furthermore, it is possible to user's imaging thus form head portrait, this head portrait can be used in video-game or other meter
In the environment that calculation machine generates.
In another illustrative embodiments, processor is used for identifying and follow the tracks of the people or the fortune of object being just imaged
Dynamic.This processor can be same processor recited above, or it can be other processors.
Furthermore, it is possible to adjust position and the degree of depth of imaging window substantially in real time.This will ensure that the people being just imaged
Will not the most partly or entirely move to the outside of imaging window thus from the image of transmission " disappearance ".
Multiple image range-measurement systems can use multiple signal transmitter and the figure using different pseudo noise codes to be modulated
As sensor.These systems allow in Same Scene in the same time by different scope image camera to different objects
Carry out imaging.
Detailed description describe the various embodiment about the process to the single pixel in the system of full field, but
It is also applied in other application, such as, is applied to such as from the single-point sample of spot scan system.It addition, it is said
Algorithm can be realized by hardware or software.And, processor described herein can be general purpose computer/PC, micro-control
Device processed, ASIC or any other enforcement of equal value.
Although embodiments of the present invention have been described more fully with reference to the accompanying drawings, it is altered or modified it should be noted that various
Will be apparent from for a person skilled in the art.Described change and amendment are construed as including in appended power
Within the scope of the embodiments of the present invention that profit requirement is limited.Especially, the use of the pseudo noise code being discussed below is not
It is confined to the use of particular code；Other pseudo-random sequences can also be used.Further, it is possible to use other kinds of spread spectrum code,
Include but not limited to maximal-length sequence (mcode), Gold code, Walsh hadamard sequence (Walsh-Hadamard
Sequence), quaternary sequence (quaternary sequence) and Kasami code (Kasami code).
There is the AMCW scope image camera in fixed clock cycle (that is, the fixed frequency of the square wave that driver is launched) at model
Enclose the distance between image camera and object make to reflect light with during the phase more than 360 ° launching light in range finding object
Can be potentially encountered difficulty.This is because phase shift is actually unable in enough more than 360 °.Due to the character of phase shift, the phase shift of 360 ° with
The phase shift of 720 ° is the same, as the phase shift with 0 °.It is similar to, as the phase shift of the 270 ° phase shift with 630 °.This is for common
Scope image camera is likely to result in difficulty, because the phase shift of two objects is probably equally, so when described object is actual
But it is confirmed as during upper wide apart from the identical distance of camera.Become by the scope of the object in the range of implementing needed for only including
As window, the problems referred to above can be prevented effectively from according to assembly of the invention.
It addition, the one or more objects from scene scatter to the light in objects can cause interference, because
The light of this scattering has the effect of the floor light light source of bigger path (referred to as multipath).Selective Range Imaging
Can have the interference light of the path outside the window of the selected degree of depth by refusal and overcome this interference.
Claims (36)
1. the method object of the optional distance from Modulation and Amplitude Modulation continuous wave scope imaging device being carried out imaging, the party
Method includes:
Launching modulation illumination sign, wherein said modulation illumination sign pseudo noise code carries out intensification modulation；
At imageing sensor, receive the reflection of described modulation illumination sign, the signal of described reflection is made even by integral process
Mean, thus form multiple samples of the modulation illumination sign of reflection, wherein said sample is to use described pseudo noise code to adjust
System；
Determine the phase shift between launched modulation illumination sign and the plurality of sample, to determine at least one phase shift；
Determined by based on, phase in-migration determines the scope between described device and at least one object；And
Imaging window, Qi Zhongsuo is determined when pseudo noise code of sampling is relevant to the illumination of received reflection modulation pseudo noise code
State sampling pseudo noise code and outside described imaging window, become uncorrelated with the illumination of received reflection modulation pseudo noise code,
And the integration of described incoherent signal forms the signal being equivalent to constant background illumination.
Method the most according to claim 1, wherein based on described illumination modulation pseudo noise code and sample modulation pseudo noise code
Between time delay determine the distance between described device and described imaging window.
Method the most according to claim 2, wherein can by adjust illumination modulation pseudo noise code and sample modulation pseudo-with
Time delay between machine code sets and adjusts described distance.
Method the most according to claim 1, wherein Modulation and Amplitude Modulation continuous wave scope imaging device is only to described imaging window
Interior object carries out imaging.
Method the most according to claim 1, the method also includes compensating signal bias and noise.
Method the most according to claim 1, wherein operation frequency based on described pseudo noise code determines described imaging window
Distance between leading edge and the back edge of mouth.
Method the most according to claim 6, wherein can by adjust described pseudo noise code operation frequency set and
Adjust the distance between leading edge and the back edge of described imaging window.
Method the most according to claim 7, the method also includes compensating signal bias and noise.
9. a Modulation and Amplitude Modulation continuous wave scope imaging device, this Modulation and Amplitude Modulation continuous wave scope imaging device includes:
Illuminator, is configured to launch modulation illumination sign, and wherein said modulation illumination sign is to carry out bright by pseudo noise code
Degree modulation；
Imageing sensor, for receiving the reflection of described modulation illumination sign, this imageing sensor is configured to integration and is received
The signal arrived, wherein takes the mean on integration period to described signal and modulates multiple samples of illumination sign with formation reflection
This, wherein sampling uses described pseudo noise code to modulate；And
Formed by relevant between the illumination modulation pseudo noise code of described sampling pseudo noise code and the described reflection received
Imaging window, wherein said sampling pseudo noise code becomes outside described imaging window with the illumination modulation pseudo noise code received
Uncorrelated, and the integration of described incoherent signal forms and is equivalent to the signal of constant background illumination；And
Processor, for determining the phase shift between launched modulation illumination sign and the plurality of sample, so that it is determined that at least
One phase shift, and relative to the modulation of modulation illumination sign, the modulation of sampling is carried out time delay.
Modulation and Amplitude Modulation continuous wave scope imaging device the most according to claim 9, wherein said processor is configured to base
Determined by, phase in-migration determines the scope between described device and at least one object.
11. Modulation and Amplitude Modulation continuous wave scope imaging devices according to claim 9, wherein said illuminator is configured to
Intensification modulation illumination sign is launched continuously when described imageing sensor is sampled.
12. Modulation and Amplitude Modulation continuous wave scope imaging devices according to claim 9, wherein said processor is further configured to
Adjust the clock cycle of described modulation illumination sign.
13. Modulation and Amplitude Modulation continuous wave scope imaging devices according to claim 9, wherein relative to modulation illumination sign
The length modulating the time delay that the modulation to described sampling is carried out can be adjusted substantially in real time.
14. Modulation and Amplitude Modulation continuous wave scope imaging devices according to claim 9, wherein relative to modulation illumination sign
The length modulating the time delay that the modulation to sampling is carried out can be adjusted substantially in real time in motion based on the object being just imaged
Whole.
15. Modulation and Amplitude Modulation continuous wave scope imaging devices according to claim 14, wherein Modulation and Amplitude Modulation continuous wave scope
Imaging device is configured to only the object in imaging window be carried out imaging.
16. Modulation and Amplitude Modulation continuous wave scope imaging devices according to claim 15, before wherein said imaging window has
Edge and back edge.
17. Modulation and Amplitude Modulation continuous wave scope imaging devices according to claim 16, wherein said imaging window is substantially
There is triangle.
18. Modulation and Amplitude Modulation continuous wave scope imaging devices according to claim 9, this Modulation and Amplitude Modulation continuous wave scope imaging
Device also includes frequency regulator, and this frequency regulator is for adjusting the operation frequency of described pseudo noise code.
19. Modulation and Amplitude Modulation continuous wave scope imaging devices according to claim 9, this Modulation and Amplitude Modulation continuous wave scope imaging
Device also includes DC compensator, and this DC compensator is for compensating signal bias and noise.
20. Modulation and Amplitude Modulation continuous wave scope imaging devices according to claim 18, wherein said imaging window be based on
The operation frequency of described pseudo noise code determines.
The method of 21. 1 kinds of distances using Modulation and Amplitude Modulation continuous wave scope imaging device to determine object, the method includes:
Launching modulation illumination sign, wherein said modulation illumination sign pseudo noise code is modulated；
Carry out modulation image sensor based on described pseudo noise code, thus catch many from the modulation illumination sign of described object reflection
Individual sample；Described imageing sensor uses integral process to take the signal of reflection for each sample in the plurality of sample
Average；
Determine the imaging window of the modulation illumination sign that receiving reflected, imageing sensor modulation puppet described in this imaging window
Random code is relevant to the illumination pseudo noise code of the reflection of the modulation of described seizure, and wherein said sensor is modulated pseudo noise code and caught
The illumination modulation pseudo noise code of the reflection caught becomes uncorrelated outside described imaging window, and described incoherent signal
Integration forms the signal being equivalent to constant background illumination；And
Determine the phase shift between the plurality of sample and described modulation illumination sign.
22. methods according to claim 21, the method also includes: determine from described Modulation and Amplitude Modulation based on described phase in-migration
Continuous wave scope imaging device is to the distance of described object.
23. methods according to claim 22, the method also includes: target back edge based on imaging window defines institute
State pseudo noise code.
24. methods according to claim 22, the method also includes:
Described object is identified in multiple images；And
In response to detect described object away from or move towards described Modulation and Amplitude Modulation continuous wave scope imaging device, and
Perform following at least one to move described imaging window:
Change described pseudo noise code；
Change described in the pseudo noise code and described pscudo-random codc modulation launched in described modulation illumination sign between imageing sensor
Time delay；Or
Change the frequency of described modulation illumination sign.
25. methods according to claim 21, the method also includes:
Set time and the image described in the described pscudo-random codc modulation of use of the pseudo noise code launched in described modulation illumination sign
Time delay between the time of sensor.
26. methods according to claim 21, wherein use modulation illumination described in the pscudo-random codc modulation being mixed with continuous wave
Signal.
27. methods according to claim 26, the method also includes:
Set time and the image described in the described pscudo-random codc modulation of use of the pseudo noise code launched in described modulation illumination sign
Time delay between the time of sensor.
28. methods according to claim 27, wherein target leading edge based on imaging window sets described time delay.
29. methods according to claim 27, the method also includes:
Target back edge based on described imaging window defines described pseudo noise code.
30. 1 kinds for determining the Modulation and Amplitude Modulation continuous wave scope imaging device of the distance of object, this Modulation and Amplitude Modulation continuous wave
Scope imaging device includes:
Illuminator, is configured to launch modulation illumination sign, and wherein said modulation illumination sign is to adjust by pseudo noise code
System；
Imageing sensor, is configured to catch the multiple samples from described object reflection modulation illumination sign out, Qi Zhongsuo
State imageing sensor be configured to the signal to described seizure be integrated on integration period and described integration period lead to
Crossing and modulated by described pseudo noise code, described signal from object reflection out, is averaged number to be formed by integral process
Multiple samples of the modulation illumination sign of reflection；
The phase between pseudo noise code is modulated by the illumination sign of described imageing sensor modulation pseudo noise code with described reflection
Close and form imaging window, wherein said sensor modulation pseudo noise code modulate with the illumination caught pseudo noise code described become
As becoming uncorrelated outside window, and the integration of described incoherent signal forms the letter being equivalent to constant background illumination
Number；And
Processor, is configured to determine the phase shift between the modulation illumination sign of transmitting and the plurality of sample, and defines use
In modulate between the time of pseudo noise code of illumination sign and the time using imageing sensor described in pscudo-random codc modulation time
Prolong to determine the position of described imaging window.
31. devices according to claim 30, wherein said processor is further configured to definition and launches described modulation illumination
Time of the pseudo noise code in signal and use described in described pscudo-random codc modulation the time delay between the time of imageing sensor.
32. devices according to claim 30, after wherein said processor is further configured to target based on imaging window
Pseudo noise code described in Edge definition.
33. devices according to claim 30, wherein use modulation illumination described in the pscudo-random codc modulation being mixed with continuous wave
Signal.
34. devices according to claim 33, wherein said processor is further configured to set launches described modulation illumination
Time of the pseudo noise code in signal and use described in described pscudo-random codc modulation the time delay between the time of imageing sensor.
35. devices according to claim 34, before wherein said processor is further configured to target based on imaging window
Edge sets described time delay.
36. devices according to claim 35, wherein said processor is further configured to mesh based on described imaging window
Mark back edge defines described pseudo noise code.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US201161483174P | 2011-05-06 | 2011-05-06 | |
| US61/483,174 | 2011-05-06 | ||
| PCT/NZ2012/000062 WO2012154065A1 (en) | 2011-05-06 | 2012-05-04 | Selective distance range imaging |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN103733087A CN103733087A (en) | 2014-04-16 |
| CN103733087B true CN103733087B (en) | 2016-11-30 |
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