how to get the extrinsic parameters of single/two cameras with DriveWorks Calibration tools?

hi, I met some problem while trying to get the extrinsic parameters of single/two cameras.

According to page 3 in NVIDIA_DriveWorks_Calibration_Tool.pdf, the calibration tool supports single, stereo and 4-cameras.

Well, I succeed to complete the example(4-cameras) in page 21 in NVIDIA_DriveWorks_Calibration_Tool.pdf. However, I got the following error while I tried to get the extrinsic parameters of single camera.

16:32:12.077: camera SVIEW_FR is ocam
16:32:18.406: Load camera image files. Supported formats: *.bmp *.jpeg *.jpg *.pbm *.pgm *.png *.ppm *.xbm *.xpm
16:32:19.814: Selected 1 images
16:32:19.825: read /home/user/WORK/data/nvidia_calibration_tool_data/hq-nov/cam_0.png
16:32:19.859: relate to master camera: NO
16:32:19.866: number of calibrated cameras: 1
16:32:27.794: Not enough markers found, cannot calibrate

I tried again with two cameras and got the same error “Not enough markers found, cannot calibrate”.

Did I miss something or make some mistakes?

Thanks for any advices.

Dear manfeyn,

Maybe your capture image has not enough markers to calibrate. Thanks.

Thanks for your reply.

I am using the image from nvidia_calibration_tool_data/hq-nov, which is installed with the NVIDIA DriveWorks. The image is also included in the nvidia’s pdf. You can check the figure 22(Find Circles) in the NVIDIA_DriveWorks_Calibration_Tool.pdf.

Maybe I shall use the checkerbox instead?

Dear manfeyn,

Did you modify “Circular Maker Configuration” in Find Circles?
Maybe if change properties in Circular Maker Configuration, you can find more markers. Thanks.

I only changed the default value of marker number from 8 to 4 since the marker image only contains 4 marker.

Sure, I will change other properties in Circular Maker Configuration and post the results later(maybe next Monday I guess).

Thanks for your reply. And please do not hesitate to add more comments if you find something might be helpful.

Hi, mania91,

I tried to change properties in Circular Marker Configuration and still failed to find enough markers.

Here are my steps:

  1. open the Driveworks Calibration tools.
  2. open the sample rig file from driveworks/data/tools/calibration/hq-nov/.
  3. change to the “Extrinsic calibration” tab.
  4. select the “SVIEW_FR” and “SVIEW_LE” camera.
  5. load the cam_0.png and cam_2.png from driveworks/data/tools/calibration/hq-nov/.
  6. change “4 Circles Marker” to “8 Circles Marker” in the Advanced Marker section.
    6(optional). change findPatternRansacIterations from 50 to 100.
  7. click the “Find Circles” button.

Then I got “Not enough markers found, cannot calibrate”.
I uploaded two pictures( that might be helpful.

Did I make something wrong?

Dear manfeyn,

Please try it with below step and values. Thanks.

Step 0 ~ 4 : Same
5. Use “4 Circles Marker”
6. In “invidia_calibration_tools_1.jpg” file, please change below parts values
a. findPatternRansacIterations : 50 -> 30
b. minNumberOfCountourPointsinMarker : 30 -> 42
c. minAreanInPixelsOfMarker : 40 -> 60
7. Click the “Find Circles” button.

Thanks for your reply.
Well, I tried again with you suggestion and still got the same answer.

Are you sure about using “4 Circles Marker”?
There are 8 circles in the marker. You verify it by checking “invidia_calibration_tools_0.jpg”.

Thanks again :).