DLP 3D SDK - Trigger related question

Hello Athena,

Did you make the connections stated in the trigger cable assembly guide? http://www.ti.com/lit/df/tidu457a/tidu457a.pdf

Please make sure that you connect the trigger cable to the input trigger connect on the LightCrafter 4500 as well. Please reference the schematic for the correct trigger connector: http://www.ti.com/lit/df/tidr933/tidr933.pdf

Best regards,

Blair

Hello Athena,

         Have you solved the problem ? I always meet the same problem "The DLP at step4-6 can't project any patterns." no matter I use trigger out1 (J14 pin 2 and 3) or  trigger in1(J11 Pin 2 and 3).

        Thanks very much.

Best wishs,

Yu Peng.

Hello Blair,

Have you solved the problem ? I always meet the same problem "The DLP at step4-6 can't project any patterns." no matter I use trigger out1 (J14 pin 2 and 3) or trigger in1(J11 Pin 2 and 3).

Thanks very much.

Best regards,

Yu Peng.

Hello Peng,

Are you referring to the steps in http://www.ti.com/lit/ug/dlpu019/dlpu019.pdf Section 3.4 Projector and System Calibration procedure?

Make sure you are able to perform steps 1 - 3 successfully. 

Can you also attach your Command Line log?

Regards,

Sanjeev

Are you able to perform Step #2 successfully? Prepare DLP LightCrafter 4500 (once per projector) option. Please run this step and let me know what you are seeing.

Hello Ssnjeev,

       I have solved the problem. In the calibration procedures, the projector can cast corresponding patterns now, and the calibration procedures are successful. I changed tow value:

           Actualy, I don't know why, what's the meaning of the "LCR4500_SETTINGS_PATTERN_TRIGGER = 0".

          And I have noted "5.1 General Troubleshooting Steps" of "TIDA-00254: Accurate Point Cloud Generation or 3D Machine Vision Applications using DLP® Technology and Industrial Camera":The formula for the conversion to and from frame rate to exposure is:
106 = Camera Frame Rate × Projector Exposure Time

If it's true, then the Projector Exposure Time is too low because the Camera Frame Rate will not be so high.

        Besides,I can not generate a Depth Map but a black picture,and the"point_cloud.xyz " is empty:

                                                                                                  Depth Map

 

     At last, I have not detected any trigger signal from the camera via the cable beteewn DLP and Camera in whole process.I don't know if there should be some trigger signals from camera to trigger the DLP4500?

 

     Thanks a lot!

Regards,

Yu Peng

 

Do you mean when you set "LCR4500_SETTINGS_PATTERN_TRIGGER = 0" values to 0, 3, 4, 5, ... it works?

Because now we are able to perform calibration doesn't me the calibration is successful. Did you perform both Camera and projector calibration. What are the xml settings generated in the Output directory? What are the results of the calibration...

A poor calibration result can also lead to poor point cloud. So i think we should still go back and look at the calibration.

Regards,
Sanjeev

      Yes,when the values are set to be 0, 3, 4, 5, ...the projector can cast white pattern or chessboard, and I do the calibration well.

      I think: the circuit of the external trigger is damaged,so the DLP350 can't receive trigger from the camera.

      The "LCR4500_SETTINGS_PATTERN_TRIGGER" = 1 or 2 are corresponding to the Trigger 1 In and Trigger 2 In(J11) for external trigger from camera,respectively. But when the circuit of the external trigger is damaged, the DLP350 can't receive trigger signals from the camera. However, when the values are 0, 3, 4, 5, ...the projector don't need external trigger from camera, but receive some internal triggers from system. That's why when 1 or 2 it does not works,but when others it works. 

 

   The "calibration_data_camera.xml" is :

     

      The "calibration_data_projector.xml" is :

  The reprojector erros may be lower sometimes.

Regards,

Yu Peng

Hello Yu Peng,

Yes, could be problem with DLPC350 not getting the trigger signals from the Camera.

Note the 1 and 2 map to external trigger signals the definition is as follows

INTERNAL = 0, /**< Internally triggered pattern */
EXTERNAL_POSITIVE = 1, /**< Externally triggered pattern by a low to high transition */
EXTERNAL_NEGATIVE = 2, /**< Externally triggered pattern by a high to low transition */
NONE = 3, /**< No trigger */
INVALID = 4

So you have just 0 to 3 valid settings.

There is another parameter for mode settings :

MODE_0_VSYNC = 0, /**< Mode 0 triggering, uses Vsync signal */
MODE_1_INT_OR_EXT = 1, /**< Mode 1 internal or external trigger */
MODE_2 = 2, /**< Mode 2 triggering */
MODE_3_EXP_INT_OR_EXT = 3, /**< Mode 3 expanded internal or external trigger */
MODE_4_EXP_VSYNC = 4, /**< Mode 4 expanded triggering with VSYNC */
INVALID = 5

Here the default settings is taken as MODE_1_INT_OR_EXT

Was the Camera triggering projector ever worked for you?

Since you are able to trigger the camera you are using a valid INTERNAL = 0 option setting, in this mode you should configure camera in external trigger mode, so projector triggering the camera, further, you must adjust the camera exposure setting matching the projector trigger period. If possible set it to lesser value so that Camera completes it exposure before receiving the next trigger pulse.

Also enable the debug mode to see how the captured images look. If you are able to compile the code, refer to main.c

int main()
{
// System Variables
dlp::PG_FlyCap2_C camera;
dlp::LCr4500 projector;

// Strucrtured Light modules
dlp::GrayCode structured_light_vertical;
dlp::GrayCode structured_light_horizontal;
unsigned int total_pattern_count = 0;
-----
-----

camera.SetDebugEnable(false); //Make it TRUE
projector.SetDebugEnable(false); //Make it TRUE

---
---

}


Regards,
Sanjeev

Dear Sanjeev,
I am sure that my DLP is damaged, beacause when I use another DLP 4500 to work with my camera and computer it is well.
I want to know how can I get the DLP repaired or exchanged?Regards,
Yu Peng

You can contact Wintech Digital China for repair work.

Hello Sanjeev,

       Thank you for your help. I have changed a new DLP LightCrafter 4500,and it works well.

        But there is another question with me. I want to generate some pattern sequence with different colour and patterns with different width, then apply them when I do scanning. For example, I generate a sequence in Pattern Sequence mode with DLP LightCrafter 4500 Contral Software, but I don't know how and where to save the sequence, and how to apply it to scan objects when I run the 3D_Scanner_LCr4500_PGcam. How can I do? Can I click on the "Save Solution"? Then add it to Firmware File "DLPR350PROM_v2.0.0_no_images.bin"? Then Upload the new Firmware File to DLP LightCrafter 4500 Contral Software?

Yu Peng

Hello Yu Peng,

Are you using different scheme for scanning? Are you not using GrayCode structured light mode for scanning the object? The way the SDK is setup allows configuring and running the hardware in Graycode 3D scanning approach only. If you are not using this scheme, then you need to modify the 3D SDK source, you can create firmware image with your custom patterns and trigger mode, 

From the SDK, you can still use the Calibration procedure to generate the Camera and Projector calibration data, when scanning, you need to call camera routine to start generating triggers before camera exposure, and grab all the images, after that you can use the images to decoding as per your algorithm. 

Not sure if it is good place here to explain all steps for 

Regards,

Sanjeev

 

No , I also want to use GrayCode structured light mode to scan objects,but only change the colour and width of each pattern. Then I cannot generate pattern sequences to do scanning by the DLP LightCrafter 4500 Contral Software , but only modify the SDK? The DLP LightCrafter 4500 Contral Software only can be used to display patterns,but not generate patterns? If I want to generate a new pattern sequence and do scanning , I should modify the SDK?
I have generated some pattern sequence images by Matlab, can I load them to Firmware to do scanning instead of te orignal Firmware, not just display them by contraling the DLP LightCrafter 4500 Contral Software ?

If I can only modify the SDK, where and how can I do ?

For changing the color, you can edit below parameter in the
structured_light_horizontal_settings.txt and structured_light_vertical_settings.txt files

PATTERN_SETTINGS_COLOR = WHITE

Currently it applies same colors to all the patterns.

What do you meant by width of the pattern? You mean bit-depth? if so why you need 8-bit for displaying a graycode pattern, graycode pattern can be represented in 1-bit.

Regards,
Sanjeev

Hello Sanjeev,
Yes, I can set the color.
I mean how can I use the DLP to project patterns with more narrow stripes?
Otherwise, can I measure the size (length\width\height) of the point cloud imported into MeshLab? I really don't know how to do measurement and filtering(or smooth?) in MeshLab. And I have not found any valid user guide of MeshLab.

Regards,
Yu

Hello Yu,

I mean how can I use the DLP to project patterns with more narrow stripes?

>> I don't understand what do you mean narrow strips. By definition the Graycode algorithm goes all the way to 1 column width on the DMD. 

Meshlab is just one tool to view the point cloud data, there are several others you can google on the web, Meshlab wiki link https://en.wikipedia.org/wiki/MeshLab 

Regards,

Sanjeev

Hello Sanjeev,

        I have some questions about DLP4500.

1、I have noted that the resolution of Z-axis can be 44.9um:

            I want to know it's only the theoretical value or actual value we can obtain? I have fond that we cannot do scan in such a small view field of 15mm*24mm because of the physical size of DLP and camera.

           At the same time,  the view field must larger than the pattern projected by DLP. But the pattern size is always much larger than 15mm*24mm when we get a clear pattern, as the focal length of the projector lens of DLP is 140mm.

           And why the angle between DLP and camera is 45 but not 60 or 90 in the formula upon?  Is it an experience value? Based on the formula, the angle is bigger the resolution is higher.

          What is the best resolution or precision have you obtained as far as now? 

2、Why we cannot get a complete depth map  but a defective map(round or other graph) after we scaned a flat plate,as the reprojection error is higher than 2:

 

   A normal depth map should be :

3、In the calibration procedures, if camera is perpendicular to the calibration board or object,and DLP project pattern tiltly on the calibration board,or object, can we get a better reprojection error and point cloud?

 

       We find it is very difficalt to do calibration and the reprojection error is much larger than 2, and the depth map and point cloud we get are very bad. How can we do the optimization?

 

      Thanks very much!

Regards,

Yu Peng.

#1. We are working on this. The values are theoretical calculations.

#2. Do you mean the that the first image has more errors when compared to the second image (flat rectangular surface)?

#3. For Perform camera calibration -

You can actually keep camera free i.e., not hooked to fixture; this way you can capture many chessboard snapshots at different variation. Once the camera calibration is done; for Projector calibration step, you can mount the camera at the fixture and then perform the Projector calibration.

Also looking at Projector and Camera fixture; the projector seems to be too close to the chessboard, is it in focus? What is the distance from projector lens to the flat surface. You mentioned 140mm as minimum focus distance, so is the current distance b/w projector and the surface > 140mm? Have you changed the projector lens in case if you have kept close to surface?

Regards,

Sanjeev

hello peng,
Have you solved the problem ?I have also encountered this problem.In the step 1-3, the software can success to work.In the step 4-6,The projector can't run correctly. When the camera and the projector are calibrated, the projector can not always project white and checkerboard.But Camera can capture image.How can I fix the problem?
Thank you very much.
Chen Sheng