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D435 calibration parameters are suddenly reset back to gold/factory

MBerg22
Beginner
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We calibrate our cams to get better performance/accuracy and that works well. It happens though quite often that the cams lose the calibration and we have to re-calibrate. Last time this happened we read out the calibration parameters with "Intel.Realsense.CustomRW -r -sn xxx -f file.xml" before re-calibrating. It then came to our mind that we should try to restore the cam back to gold/factor so we did that with "-g" and after that we read out the parameters and stored in file "file_gold.xml". Now we compared the file.xml and file_gold.xml and they are IDENTICAL!!

 

So all in all this means that when we have the problem that a cam has become uncalibrated it has actually reset it parameters back to gold/factory!!!

 

In what situations can this happen??

 

Regards,

Mats B

 

 

See also related topic on the forum:

https://forums.intel.com/s/question/0D50P00004Krr3JSAR/recalibration-of-d435-often-needed?language=en_US

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MartyG
Honored Contributor III
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There is the free public version of the Dynamic Calibrator software that most people use. There is also an enhanced 'OEM' version with extra features such as the ability to write both extrinsics and intrinsics, calibrate multiple cameras and link to them remotely. The enhanced version can be obtained through purchase of the $1500 USD OEM calibration board in Intel's online click store, or with the software only without the board if you are registered with Intel as a Non Disclosure Agreement (NDA) customer.

 

It looks as though you are using the ordinary public version of the calibration software, so your problem is not likely related to an OEM-version incompatibility with CustomRW. Thanks for the information you provided.

 

The incompatibility between the OEM calibrator and the public version of CustomRW was mentioned around March 2018. I do not have information about whether the incompatibility has been corrected since then.

 

The CustomRW tool is useful for permanently writing calibration details to the camera hardware, but it is not the only means of calibrating multiple cameras. Aside from the OEM calibrator system, Intel have also used an open-source software called Vicalib to calibrate multiple 400 Series cameras by showing a calibration board to each camera in turn.

 

https://github.com/arpg/vicalib

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MartyG
Honored Contributor III
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Have you been using the special OEM version of the calibration tool before you tried a gold reset with CustomRW, please? Apparently, the OEM calibrator is not compatible with CustomRW, which can lead to problems when doing a gold reset if an OEM calibration was performed before that.

 

https://github.com/IntelRealSense/librealsense/issues/1588

 

It may also be worth looking at the circumstances in which your cameras are repeatedly losing calibration. Typically, the 400 Series cameras should only need recalibrating after a physical shock such as a hard knock or a drop onto the ground. I believe that severe vibration, such as when the camera is mounted to a mobile robot / drone that is experiencing rough terrain or strong chassis vibration, may also provide such a shock if the vibrations are not dampened.

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MBerg22
Beginner
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OEM calibrator ? Is that the Intel.Realsense.DynamicCalibrator? That is anyway the one we are using according to this guide: https://www.intel.com/content/dam/support/us/en/documents/emerging-technologies/intel-realsense-technology/RealSense_D400_Dyn_Calib_User_Guide.pdf

 

We use the latest linux version (2.6.8.0) installed via apt (aws).

 

We use the following workflow for our cams:

1) Initially calibrate with DynamicCalibrator

2) Save calibration data with "CustomRW -r..."

3) The cam works fine for some time (days-weeks)

3.5) suddenly the accuracy is very bad by unknown reasons. Can happen without really using the cam at all.

4) We restore the cam with "CustomRW -w ..."

5) Everything works fine again (for some time)

 

A) So it doesn't really seem that we have a problem with incompatibility. Also vibration nor shock seems to be the problem since we can fix it by just re-writing the saved calibration data. The problem is what is happening on bullet 3.5 and why it happens etc.

 

B) Regarding the CustomRW tool, it seems to be on version 2.6.7.0 !? If that should not be used together with version 2.6.8.0 of the DynamicCalibrator how shall we be able to read and write calibration data? Shall we use the CustomAPI and code our own read & write tool?

 

C) When will CustomRW be compatible again?

 

D) Is it that CustomRW is not compatible with the DynamicCalibrator or is that that it is not compatible with certain fw versions of the D435?

 

 

 

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MartyG
Honored Contributor III
876 Views

There is the free public version of the Dynamic Calibrator software that most people use. There is also an enhanced 'OEM' version with extra features such as the ability to write both extrinsics and intrinsics, calibrate multiple cameras and link to them remotely. The enhanced version can be obtained through purchase of the $1500 USD OEM calibration board in Intel's online click store, or with the software only without the board if you are registered with Intel as a Non Disclosure Agreement (NDA) customer.

 

It looks as though you are using the ordinary public version of the calibration software, so your problem is not likely related to an OEM-version incompatibility with CustomRW. Thanks for the information you provided.

 

The incompatibility between the OEM calibrator and the public version of CustomRW was mentioned around March 2018. I do not have information about whether the incompatibility has been corrected since then.

 

The CustomRW tool is useful for permanently writing calibration details to the camera hardware, but it is not the only means of calibrating multiple cameras. Aside from the OEM calibrator system, Intel have also used an open-source software called Vicalib to calibrate multiple 400 Series cameras by showing a calibration board to each camera in turn.

 

https://github.com/arpg/vicalib

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