Where to find the ToF and Hires sensors calibration?

oasisartisan

Hello, I have the Starling Max with the C29 cameras.

I am able to find intrinsic calibration files for the tracking cameras.

:~$ voxl-check-calibration
Calibration File Status:
Present /data/modalai/voxl-imu-server.cal 
Present /data/modalai/opencv_tracking_front_intrinsics.yml 
Present /data/modalai/opencv_tracking_down_intrinsics.yml 
Present /data/px4/param/parameters_gyro.cal 
Present /data/px4/param/parameters_acc.cal 
Present /data/px4/param/parameters_level.cal 
Present /data/px4/param/parameters_baro_tc.cal 
Present /data/px4/param/parameters_mag.cal

I am trying to get the ToF and Hires camera calibration.

Since ToF also publishes a point cloud, the intrinsics must be there already somewhere for ToF at least ?

jimbow77

I am also interested for the ToF, and I have the C29 config as well. I tried using voxl-calibrate-camera on the tof_ir stream but it seems I will need a checkerboard with different reflectivity for the black and white squares (my printed one doesn't work well). However, I was able to generate an intrinsics calibration file just fine with my printed checkerboard for the hires camera.

My guess is the intrinsics for the ToF are hard-coded into the sensor itself and not handled by ModalAI directly, but I don't know for sure.

Any suggestions for the ToF sensor would be appreciated.

Alex Kushleyev

@jimbow77 and @oasisartisan ,

TOF V1 (which is now EOL, so you don't have it on Starling 2 Max) was set up the following way:

The calibration data was downloaded the first time the sensor was used and stored in /data/misc/camera/, then re-used for next time
calibration files include pmd.spc, tof_cal_eeprom.bin and irs10x0c_lens.cal - the latter likely containing the intrinsics calibraiton data (although i have not checked explicitly)

TOF V2 (what is shipping in Starling 2 (and Max) ), is set up so that the TOF Library downloads (via i2c) the calibration data each time the voxl-camera-server starts. This is done internally to the TOF libraries. I don't know exactly why there is a difference between how the calib data is handled for two sensors by the TOF software, but this is how our sensor vendor helped us set it up. The TOF processing software downloads the calibration from the sensor each time voxl-camera-server starts and applies it to generate the point cloud. It may be possible to get the TOF intrinsics using the TOF library API, but we have not checked.

Do you have a specific reason why the TOF intrinsics are needed?

If you wanted to calibrate the TOF sensor yourself, then you would either need a checkerboard some material that is IR reflective ("white") and non-reflective ("black"). Alternatively, you could use an array of IR leds (or IR reflective dots + IR light) and use dot pattern detector as opposed for checkerboard for calibration.

Regarding Hi-res cameras, the intrinsics are not calibrated and not included. It can be calibrated using our camera calibration app (voxl-camera-calibration), but you should do it at half resolution or smaller (not full size like 4056x3040), otherwise the app runs very slowly. If you need more details how to calibrate at high resolution, let me know (involves downscaling exactly by a factor of 2 and then upscaling the resulting intrinsics)

Alex