Calibration of D415 with external software

[DKoma1]

I want to calibrate D415 camera with an external calibration software (as Matlab calibrator). For these reasons I need to capture raw IR-images. As I read here /message/540365# 540365 https://communities.intel.com/message/540365# 540365 Realsense Viewer saves already rectified ones. To get unrectified images from D435 it was suggested to save in camera following distortion parameters: fx=fy=633.33; pxy=640,400; all 0 for distortion, unit matrix for rotation and no translation. Which parameters should I write in D415 to get the raw IR images?

[MartyG · Accepted solution]

There is existing calibration software for the 400 Series cameras called the Dynamic Calibration Tool.

https://downloadcenter.intel.com/download/27955/Intel-RealSense-D400-Series-Calibration-Tools-and-API?v=t Download Intel® RealSense™ D400 Series Calibration Tools and API

If you need an unrectified IR format, Y16 format is unrectified. It only supports a couple of resolutions though, as it is intended for camera calibration rather than everyday use in applications.

[DKoma1]

Thank you for the answer. Do I understand correct: if in Realsense Viewer I choose Y16 format, than the pictures will be unrectified, and if Y8 - then rectified?

I have an aditional question: is it normal that D415 in Y16 mode saves images with kind of square structure (light dots) as on an attached picture? Can I avoid it?

[MartyG]

Yes, that is correct. Y16 is unrectified and Y8 is rectified.

Rectification takes place inside the camera, in its Vision Processor D4 component, and then rectified data travels through the USB cable to the computer.

The camera can project a random pattern of dots onto objects that help it to process low-detail surfaces such as doors and windows by adding texture to the scene. You can reduce the visibility of the dots by reducing the Laser Power setting in the RealSense Viewer.

[DKoma1]

The picture which is attached above is taken with an IR- projector turned off. So the square structure is not a projector, but an "modification" of an image. If I switch to Y8, this structure disappears. I take the images with Realsense Viewer with following settings 1920*1080, 15 fps, Y16 or Y8.

[MartyG]

My apologies, could you provide further explanation please about what you mean about a "square structure (light dots)". Thanks!

[DKoma1]

This is a zoomed version of the picture which was attached above. You may see that every second pixel in every second raw is much brighter then the neiboring pixels. This I called light dots.

[MartyG]

Thank you very much for your patience. I thought that this was what you were referring to but wanted to make sure.

I located a couple of other cases where this pattern has occurred on Y16.

https://github.com/IntelRealSense/librealsense/issues/1519# issue-312951808 Artifacts in 1920x1080 IR image in D415 · Issue # 1519 · IntelRealSense/librealsense · GitHub

[DKoma1]

Thank you:)