CN105068384B - A kind of laser projector time for exposure control method of hand-held laser 3 d scanner - Google Patents
A kind of laser projector time for exposure control method of hand-held laser 3 d scanner Download PDFInfo
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- CN105068384B CN105068384B CN201510490395.2A CN201510490395A CN105068384B CN 105068384 B CN105068384 B CN 105068384B CN 201510490395 A CN201510490395 A CN 201510490395A CN 105068384 B CN105068384 B CN 105068384B
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Abstract
A kind of laser projector time for exposure control method of hand-held laser 3 d scanner, comprises the following steps：1) the time for exposure Ts of laser projector in a camera sampling period is set as the initial value of feedback control, and the view data of acquisition camera；2) screening obtains real laser line projection in the image that camera is gathered；3) after the connected region of laser line projection is obtained, the laser of statistical result and setting is rationally exposed interval and is compared by the pixel in statistics connected region, if belonging to the reasonable exposure gray scale interval, using Ts as the time for exposure of laser projector, otherwise, Ts is adjusted.A kind of scanning of present invention offer works well, the laser projector time for exposure control method for the hand-held laser 3 d scanner that scanning accuracy is higher.
Description
Technical field
The present invention relates to hand-held laser 3 d scanner, especially a kind of hand-held laser three-dimensional scanning method.
Background technology
Hand-held the Airborne Laser Scan with its strong antijamming capability, accuracy of detection it is high, it is easy to use the advantages of progressively by
Used in fields such as various industry, archaeology, medical treatment, teaching.Compared to the spatial digitizer of White Light Projection principle, laser 3 d scanner
Object table region feature can be extracted from each group of synchronous two field picture and calculates a part of surface point cloud for obtaining scanned object, with
And due to laser projection light intensity more it is big thus allow to catch the camera of its image can be not produce the shutter of motion blur
Time is exposed, therefore can more be adapted to be scanned in the state of continuous continuous moving with hand-held mode.Further, since
The unicity of the wave band of laser, ambient light can be largely removed to it by installing bandpass filter mirror additional before camera
The influence of scanning process, makes the 3-D scanning of its profiling object surface being applied under outdoor natural light environment.
Thrown inside current hand-held laser 3 d scanner by the laser of two and the camera of the above and one and the above
Shadow device is constituted, its all position relationship each other before scanning demarcation, it is known that in scanning two and the above
The characteristic point of camera synchronous acquisition target object surface is used for the 3 d space coordinate position of location instrument itself, and collection is thrown
The laser projection pattern of shadow to target object surface is used for the surface cloud data for obtaining target object.Different colours and material
Body surface, the reflection for the reflection efficiency and natural light of laser is not quite similar, so if with the laser of constant brightness
Projector goes to irradiate scanned object, may obtain the laser projection image of different gray scales, excessively bright or secretly can influence excessively
The effect and precision of scanning.
Exemplified by only projecting the target object surface that the laser projector of wall scroll linear laser projects certain gray scale, such as scheme
It is abscissa direction perpendicular to laser direction, with laser lines in camera gathers the laser pattern obtained shown in 1
The heart is origin, and the pixel distribution of analysis in this direction is calculated line by line.Fig. 2 is the one-dimensional Luminance Distribution song perpendicular to laser direction
Line, ordinate is the gray value in pixel, dark to bright from 0 to 255 correspondences.Target object surface non-laser-irradiated domain domain in example
The average gray being imaged on camera is 40 or so, laser duration of the scanner during a camera shutter opening
Be set to 1ms, 2ms and 4ms, using gray value as 100 as distinguish whether be laser pattern threshold values.The laser duration sets
During for 2ms, the laser width that its brightness distribution curve is shown is in 3 pixels or so；It is wide that the laser duration is set to laser during 4ms
Spend for 11 pixels or so, need accurately to identify laser in target object in the image that camera is gathered during due to scanning
The contour line on surface, wide laser lines can lead to not obtain accurately surface characteristics, so as to reduce the precision of scanning；Swash
The overall gray value of laser is more or less the same below 100 with the gray scale in non-laser-irradiated domain domain when the light duration is 1ms,
Therefore the pattern-information of laser can not be effectively extracted in the background of image.
The content of the invention
In order to overcome existing hand-held laser 3 d scanner to cause what scanning was present using the laser projector of constant brightness
Scanning effect is poor, scanning accuracy is relatively low deficiency, the present invention provide it is a kind of scan work well, that scanning accuracy is higher is hand-held
The laser projector time for exposure control method of laser 3 d scanner.
The technical solution adopted for the present invention to solve the technical problems is：
A kind of laser projector time for exposure control method of hand-held laser 3 d scanner, the control method is included such as
Lower step：
1) the time for exposure Ts for setting the laser projector in a camera sampling period is used as the initial of feedback control
Value, and the view data of acquisition camera；
2) screening obtains real laser line projection in the image that camera is gathered；
3) after the connected region of laser line projection is obtained, the pixel in statistics connected region, by statistical result with setting
Fixed laser rationally exposes interval and is compared, if belonging to the reasonable exposure gray scale interval, regard Ts as laser projector
Time for exposure, otherwise, adjust Ts.
Further, the step 3) in, it is grey per a line along the normal vector direction search for all positions of laser rays identified
The pixel point set that the maximum pixel of degree is obtained is referred to as the crestal line that the laser projects lines；Count the laser projection pattern
In each crestal line gray value, by statistical result and setting reasonable exposure gray scale interval be compared, if belonging to the conjunction
Reason exposure gray scale interval, using Ts as the time for exposure of laser projector, otherwise, adjusts Ts.
Further, the reasonable exposure is interval includes lower limit experience threshold values Gth1 and upper limit experience threshold values Gth2, counts
Number N1, the pixel higher than Gth2 of pixels of all pixels Pi gray scale Gi less than Gth1 in the crestal line of the region laser rays
Number N2 and the pixel number N3 between Gth1 and Gth2： Finally judge shared by the normal exposure pixel that gray value is between Gth1 and Gth2
Ratio whether be more than experience threshold values：If it is the setting of laser exposure values is completed；IfIt is then to increase come the time for exposure Ts of feedback control laser projector according to the size of N1 and N2 value
Big or reduction：If N1>N2, then tune up Ts, on the contrary then turn Ts down, return to step 1).
Either：The step 3) in, the row of laser projection line i-th is obtained from the connected region of the laser rays identified
The pixel of normal direction effective line width and the total number Wi, 1≤i of sub-pix≤n, n are total line number, and obtain the laser in entire image
The average effective line width of projection line
The laser rationally exposes interval including threshold values Wth1 and Wth2 above and below line width, ifThen
Complete the setting of laser exposure values；IfTs is then tuned up, ifThen turn Ts, return to step 1 down).
Again either：The step 3) in, the flat of its all pixels is counted from the connected region of the laser rays identified
Equal gray scale
The laser rationally exposes interval including threshold values EGth1 and EGth2 above and below average gray, ifThen complete the setting of laser exposure values；IfTs is then tuned up, ifThen turn Ts, return to step 1 down).
Further, the step 2) in, gray value is obtained with edge extracting method in the image that camera is gathered high
Pattern-recognition is carried out in the connected region of setting threshold values, and according to its shape facility, screening obtains real laser line projection.
The projection frequency of the laser projector is synchronous with the frequency of exposure of camera, i.e., laser projector is in camera
It is in running order in the shutter opening period, and laser pattern projector device is within the period of the shutter closure of camera
Closed mode.
Further, when the length of the synchronous time for exposure of camera is more than or equal to the unlatching of described laser projection device
Between.
The present invention technical concept be：By the scanning accuracy of hand-held laser 3 d scanner directly depends on camera institute
The laser projector photographed projects the image quality of the projection pattern on scanned object surface, and image quality is largely
It is whether suitable depending on its brightness on the photo-sensitive cell inside camera.During the deeper object of scanner scanning color for
To normal exposure, it is necessary to increase the projection brightness of laser projector；And then need to reduce laser when scanning the shallower object of color
The projection brightness of projector obtains normal exposing patterns.
Hand-held laser 3 d scanner of the present invention is taken the photograph by the regulation to the laser projector opening time at one
As head exposure cycle in can obtain the suitable laser projection pattern of exposure simultaneously, so as to ensure hand-held laser 3 d scanner
Scanning accuracy.Compared to the spatial digitizer of the laser projector of constant brightness, hand-held laser scanning scanner of the present invention
Requirement of the scanner to working environment can be significantly reduced, the adaptability of the respective surface color of scanning and material is improved.In addition, will
The opening time of laser projector is adjusted to significantly reduce in the shutter opening cycle of camera from whole scanning process
The power consumption of system, while it is excessively bright and damaged to eye to be also prevented from laser brightness.
Beneficial effects of the present invention are mainly manifested in：1st, scanning work well, scanning accuracy it is higher；2nd, power consumption, peace are reduced
Full property is higher.
Brief description of the drawings
Fig. 1 is the signal that the laser projector of projection wall scroll linear laser projects the target object surface of certain gray scale
Figure.
Fig. 2 is the one-dimensional brightness distribution curve of the normal orientation of laser, and ordinate is the gray value in pixel, from 0 to 255
Correspondence secretly arrives bright.
Fig. 3 is the control principle drawing of hand-held laser 3 d scanner.
Fig. 4 is the schematic diagram for triggering sequential.
Embodiment
The invention will be further described below in conjunction with the accompanying drawings.
A kind of 1~Fig. 4 of reference picture, the laser projector time for exposure control method of hand-held laser 3 d scanner is described
Control method comprises the following steps：
4) the time for exposure Ts for setting the laser projector in a camera sampling period is used as the initial of feedback control
Value, and the view data of acquisition camera；
5) screening obtains real laser line projection in the image that camera is gathered；
6) after the connected region of laser line projection is obtained, the pixel in statistics connected region, by statistical result with setting
Fixed laser rationally exposes interval and is compared, if belonging to the reasonable exposure gray scale interval, regard Ts as laser projector
Time for exposure, otherwise, adjust Ts.
Further, the step 3) in, it is grey per a line along the normal vector direction search for all positions of laser rays identified
The pixel point set that the maximum pixel of degree is obtained is referred to as the crestal line that the laser projects lines；Count the laser projection pattern
In each crestal line gray value, by statistical result and setting reasonable exposure gray scale interval be compared, if belonging to the conjunction
Reason exposure gray scale interval, using Ts as the time for exposure of laser projector, otherwise, adjusts Ts.
Further, the reasonable exposure is interval includes lower limit experience threshold values Gth1 and upper limit experience threshold values Gth2, counts
Number N1, the pixel higher than Gth2 of pixels of all pixels Pi gray scale Gi less than Gth1 in the crestal line of the region laser rays
Number N2 and the pixel number N3 between Gth1 and Gth2： Finally judge shared by the normal exposure pixel that gray value is between Gth1 and Gth2
Ratio whether be more than experience threshold values：If it is the setting of laser exposure values is completed；IfIt is then to increase come the time for exposure Ts of feedback control laser projector according to the size of N1 and N2 value
Big or reduction：If N1>N2, then tune up Ts, on the contrary then turn Ts down, return to step 1).
Either：The step 3) in, the row of laser projection line i-th is obtained from the connected region of the laser rays identified
The pixel of normal direction effective line width and the total number Wi, 1≤i of sub-pix≤n, n are total line number, and obtain the laser in entire image
The average effective line width of projection line
The laser rationally exposes interval including threshold values Wth1 and Wth2 above and below line width, ifThen
Complete the setting of laser exposure values；IfTs is then tuned up, ifThen turn Ts, return to step 1 down).
Again either：The step 3) in, the flat of its all pixels is counted from the connected region of the laser rays identified
Equal gray scale
The laser rationally exposes interval including threshold values EGth1 and EGth2 above and below average gray, ifThen complete the setting of laser exposure values；IfTs is then tuned up, ifThen turn Ts, return to step 1 down).
Further, the step 2) in, obtain gray value in the image that camera is gathered with edge extracting method and be higher than
The connected region of threshold values is set, and pattern-recognition is carried out according to its shape facility, screening obtains real laser line projection.
The projection frequency of the laser projector is synchronous with the frequency of exposure of camera, i.e., laser projector is in camera
It is in running order in the shutter opening period, and laser pattern projector device is within the period of the shutter closure of camera
Closed mode.
Further, the length of the synchronous time for exposure of the camera is more than or equal to opening for described laser projection device
Open the time.
By taking the hand-held laser 3 d scanner of two cameras and three laser projector compositions as an example, as shown in figure 4,
Ta1~Ta3 is the time for exposure that two cameras synchronously trigger continuous three shutter cycles, during the exposure in each cycle
Between equal, i.e. Ta1=Ta2=Ta3；Tb1~Tb3 is respectively the time of the unlatching of 1#, 2# and 3# laser projector, and it triggers week
Phase is 3 times of camera exposure triggering cycle.Due to laser projector and supplementary lighting sources be required to camera shutter opening it
Triggering is opened afterwards and stopping is just meaningful before camera shutter close, and otherwise camera acquired image will not be appointed
What produces influence, therefore Ta >=Tb.Camera continues on shutter after laser projector stops triggering being changed
The laser projection pattern of the target object surface of camera collection and the imaging of mark point, but also ambient light can be increased to image
Interference, therefore the camera time for exposure may be configured as laser projector start time, i.e. Ta=Tb.
The present embodiment is exposed with obtaining optimal laser according to adjusting laser projector during camera shutter opening and start the time
Light image.
By taking the hand-held laser 3 d scanner of two cameras and three laser projector compositions as an example, as shown in Figure 3.Patrol
Collect main control chip MCU to be connected with triggering interface with the exposure of two-way camera simultaneously by signal isolation circuit, control two-way is taken the photograph
As head synchronizes exposure；Three laser projectors are controlled to enter with the frequency set and opening time respectively by three metal-oxide-semiconductors
Row laser pattern projector.
Claims (9)
1. a kind of laser projector time for exposure control method of hand-held laser 3 d scanner, it is characterised in that：The control
Method comprises the following steps：
1) set a camera sampling period in laser projector time for exposure Ts as feedback control initial value, and
The view data of acquisition camera；
2) screening obtains real laser line projection in the image that camera is gathered；
3) it is every along the normal vector direction search for all positions of laser rays identified after the connected region of laser line projection is obtained
The pixel point set that the maximum pixel of a line gray scale is obtained is referred to as the crestal line that the laser projects lines；Count laser projection
Each crestal line gray value in pattern, statistical result and the reasonable exposure gray scale interval of setting is compared, if belonged to
The reasonable exposure gray scale interval, using Ts as the time for exposure of laser projector, otherwise, adjusts Ts.
2. a kind of laser projector time for exposure control method of hand-held laser 3 d scanner as claimed in claim 1, its
It is characterised by：The reasonable exposure gray scale interval includes lower limit experience threshold values Gth1 and upper limit experience threshold values Gth2, counts this
Number N1, the pixel higher than Gth2 of pixels of all pixels Pi gray scale Gi less than Gth1 in the crestal line of region laser rays
Number N2 and the pixel number N3 between Gth1 and Gth2： Finally judge shared by the normal exposure pixel that gray value is between Gth1 and Gth2
Ratio whether be more than or equal to experience threshold values Nth：If it is the setting of laser exposure values is completed；
IfThen according to the size of N1 and N2 value come the time for exposure Ts of feedback control laser projector
It is increase or reduction：If N1>N2, then tune up Ts, on the contrary then turn Ts down, return to step 1).
3. a kind of laser projector time for exposure control method of hand-held laser 3 d scanner as claimed in claim 1, its
It is characterised by：The step 3) in, the normal direction of the row of laser projection line i-th is obtained from the connected region of the laser rays identified to be had
The pixel of effect line width and the total number Wi, 1≤i of sub-pix≤n, n is total line number, and obtains the laser projection line in entire image
Average effective line width
4. a kind of laser projector time for exposure control method of hand-held laser 3 d scanner as claimed in claim 3, its
It is characterised by：The reasonable exposure gray scale interval includes threshold values Wth1 and Wth2 above and below line width, ifThen
Complete the setting of laser exposure values；IfTs is then tuned up, ifThen turn Ts, return to step 1 down).
5. a kind of laser projector time for exposure control method of hand-held laser 3 d scanner as claimed in claim 1, its
It is characterised by：The step 3) in, the average gray of its all pixels is counted from the connected region of the laser rays identified
6. a kind of laser projector time for exposure control method of hand-held laser 3 d scanner as claimed in claim 5, its
It is characterised by：The reasonable exposure gray scale interval includes threshold values EGth1 and EGth2 above and below average gray, ifThen complete the setting of laser exposure values；IfTs is then tuned up, ifThen turn Ts, return to step 1 down).
7. a kind of laser projector time for exposure control of hand-held laser 3 d scanner as described in one of Claims 1 to 4
Method, it is characterised in that：The step 2) in, obtain gray value in the image that camera is gathered with edge extracting method and be higher than
The connected region of threshold values is set, and pattern-recognition is carried out according to its shape facility, screening obtains real laser line projection.
8. a kind of laser projector time for exposure control of hand-held laser 3 d scanner as described in one of Claims 1 to 4
Method, the projection frequency of the laser projector is synchronous with the frequency of exposure of camera, i.e., laser projector is in the fast of camera
Door the opening time section in it is in running order, and camera shutter close period in laser pattern projector device be in close
Closed state.
9. a kind of laser projector time for exposure control of hand-held laser 3 d scanner as described in one of Claims 1 to 4
Method, it is characterised in that：The length of the synchronous time for exposure of the camera is more than or equal to opening for described laser projection device
Open the time.
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| CN108416238B (en) * | 2018-01-31 | 2021-04-13 | 深圳盈达信息科技有限公司 | Laser scanning module and method for shielding laser interference |
| CN109510948B (en) * | 2018-09-30 | 2020-11-17 | 先临三维科技股份有限公司 | Exposure adjusting method, exposure adjusting device, computer equipment and storage medium |
| CN110475078B (en) * | 2019-09-03 | 2020-12-15 | 河北科技大学 | Camera exposure time adjusting method and terminal equipment |
| CN112710250B (en) * | 2020-11-23 | 2022-12-23 | 武汉光谷卓越科技股份有限公司 | Three-dimensional measurement method based on line structured light and sensor |
| CN112648935A (en) * | 2020-12-14 | 2021-04-13 | 杭州思锐迪科技有限公司 | Image processing method and device and three-dimensional scanning system |
| CN114001671B (en) * | 2021-12-31 | 2022-04-08 | 杭州思看科技有限公司 | Laser data extraction method, data processing method and three-dimensional scanning system |
| CN116912451A (en) * | 2022-09-20 | 2023-10-20 | 梅卡曼德（北京）机器人科技有限公司 | Point cloud image acquisition method, device, equipment and storage medium |
| CN116485660B (en) * | 2022-11-22 | 2023-11-17 | 北京迁移科技有限公司 | Image acquisition method and three-dimensional reconstruction method |
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| US20040241556A1 (en) * | 2003-05-29 | 2004-12-02 | Bellman Robert A. | Mask, mask blank, photosensitive film therefor and fabrication thereof |
| KR20070062965A (en) * | 2004-06-15 | 2007-06-18 | 후지필름 가부시키가이샤 | Photosensitive composition, method for forming pattern, and permanent pattern |
| CN1837961A (en) * | 2005-03-22 | 2006-09-27 | 日立比亚机械股份有限公司 | Exposure apparatus and exposing method and method of manufacturing a printed wiring board |
| JP2007010785A (en) * | 2005-06-28 | 2007-01-18 | Fujifilm Holdings Corp | Method for forming permanent pattern |
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Address after: Room 102, Unit 1, Building 12, No. 998, Wenyi West Road, Wuchang Street, Yuhang District, Hangzhou City, Zhejiang Province, 311121 Patentee after: Sikan Technology (Hangzhou) Co.,Ltd. Address before: Room 611, Building 4, Zhejiang Overseas High-level Innovation Park, No. 998, Wenyi West Road, Yuhang District, Hangzhou City, Zhejiang Province, 311121 Patentee before: HANGZHOU SCANTECH Co. |
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Application publication date: 20151118 Assignee: Hangzhou silidi Technology Co.,Ltd. Assignor: Sikan Technology (Hangzhou) Co.,Ltd. Contract record no.: X2022330000832 Denomination of invention: A method for controlling the exposure time of laser projectors in handheld laser 3d scanners Granted publication date: 20170815 License type: Common License Record date: 20221223 |