Depth display range adjustment

19829127419

January 23, 2024 01:00

Hello, I would like to ask how to modify the program to achieve depth range adjustability when using python to call the depth image of the D435i camera when the color of the depth distance range is not clear (some objects cannot appear in the image).

As shown in the figure below, when the depth image is called in python in the first image, the distance of the objects in the image appears to be almost all blue and not even clear. In the second image, when invoked with Intel RealSense Viewer, different color distributions can be displayed at different distances.

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9 comments

MartyG

January 23, 2024 06:56
Hello, the links below provide Python scripting resources for configuring the color scheme and histogram on / off status for a depth image.

https://github.com/IntelRealSense/librealsense/issues/7767#issuecomment-726704671

https://github.com/IntelRealSense/librealsense/issues/7089#issuecomment-672105974
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19829127419

January 25, 2024 09:41
I still haven't solved the problem. After I opened the URL you gave me, I found that it was mainly a C++ code, but I need to write code through python.

As shown in the figure below, I need to adjust the maximum and minimum range of depth visualization through the python code.
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MartyG

January 25, 2024 10:20
The intention of the links above is to use the Python code at the link below to set the color scheme:

https://github.com/IntelRealSense/librealsense/issues/3363

And use the C++ code at the link below to find the number for the color sceme that you want to use and put that color scheme number in your Python code.

https://github.com/IntelRealSense/librealsense/blob/master/include/librealsense2/hpp/rs_processing.hpp#L764-L774

Python code for controlling the Histogram Equalization status can be found via this link:

https://github.com/IntelRealSense/librealsense/issues/9976#issuecomment-971273533
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19829127419

February 03, 2024 11:45
After trying and modifying the python code you provided, I found that the color of the depth image was reversed - red for close range and blue for far range. This phenomenon is contrary to the result of the official SDK calling the depth image, how should I deal with it?
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MartyG

February 03, 2024 11:58
If you have the color Visual Preset currently set to '2' in the script then please try changing it to '0'. This should set the preset as Dynamic (which is the default color preset of the RealSense Viewer), whilst '2' would set the preset as Near which produces different colors.
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19829127419

February 04, 2024 05:08
As you said, I changed it and found that the image is still reversed. My code is as follows, could you check it for me?
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19829127419

February 04, 2024 05:13
In addition, I have another question, such as the following code, through the aligned depth image frame to color, there is an alpha variable is set?
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19829127419

February 04, 2024 05:16
If there is any programming problem with the two pieces of code I intercepted above, could you please point it out for me? Thank you very much!
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MartyG

February 04, 2024 10:15
I cannot find a reason in your code why the depth colorization is still 'far to near' (red to blue) instead of near to far (blue to red). If you have access to the RealSense Viewer tool, please try resetting the camera's calibration to its factory-new default settings using the instructions at the link below to see whether it resolves the colorization issue in your Python program.

https://github.com/IntelRealSense/librealsense/issues/10182#issuecomment-1019854487

The official OpenCV documentation for cv2.convertScaleAbs describes alpha as being a scale factor.

https://docs.opencv.org/3.4/d2/de8/group__core__array.html#ga3460e9c9f37b563ab9dd550c4d8c4e7d

My research indicates that when using cv2.convertScaleAbs, the alpha and beta parameters are used to adjust the contrast and brightness of an image, with alpha affecting the contrast and beta affecting the brightness. Apparently the alpha value is '1' by default. My research also indicated that 0.03 is considered an appropriate alpha value for converting a RealSense depth image to an OpenCV mat. This alpha value is used by the RealSense SDK's align_depth2color.py example alignment script.

https://github.com/IntelRealSense/librealsense/blob/master/wrappers/python/examples/align-depth2color.py#L92

How is the aligned image affected if the alpha is changed from 0.9 to 0.03 please?
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