Problems calibrating multiple d435 camera units
Hej everyone,
I'm having trouble with the calibration of multiple Realsense D400s.
I am using D435 and D435i and I have set them up in a static, inward facing configuration.
System Calibration:
I am using opencv with a chessboard target with the camera's left IR imagers to determine the pose of each camera.
Everything looks good there and i can use the calculated transformation matrices to render 3D Objects from each cameras space into another camera's space with good results.
Point Clouds:
The documentation states that the depth maps align perfectly with the left IR imager.
But when iIuse the intrinsic parameters from each camera to deproject the respective depth map and combine the Pointclouds I am left with offsets between surfaces.
Camera Calibration:
My first guess was that, as I have gathered multiple used cameras over the course of 5+ years, that their calibration might be off.
So I used the depth quality tool and dynamic calibration to try and recalibrate each camera.
And now the documentation in the official documents, the forums and a new walkthrough video from a couple of days ago regarding ground truth becomes a little bit confusing to me.
Is the offset of 4.2mm supposed to be added/subtracted manually or is it done automatically?
Whatever i try, the measurements gathered with depth quality tool are almost always worse than before doing dynamic calibration.
I have confirmed that the calibration target has the correct measurements and i optimized lighting conditions to ensure that no motion blur is happening.
Any thought on this is highly appreciated. Thank You!
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Hi Hannes With D435 cameras, depth is measured from the front of the camera. You can choose to manually add -4.2 mm to depth measurements to obtain a 'ground truth' measurement from the sensor lens instead of the front glass. It is not necessary to do so though, and using the default depth measurement from the front glass is fine.
You can reset a camera to its default factory-new calibration in the RealSense Viewer tool using instructions at the link below.
https://github.com/IntelRealSense/librealsense/issues/10182#issuecomment-1019854487
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