Get distance from a saved depth image

[mnauf]

Required Info
Camera Model	D415
Firmware Version	05.13.00.50
Operating System & Version	Win10
Kernel Version (Linux Only)	N/A
Platform	PC (Lenovo Legion 5i
SDK Version	2.50.0
Language	Python
Segment	not sure what it means

Issue Description

How to get distance, given that I have a depth image from D415 saved in my machine. Please note, that I can't do Depth = depth_frame.get_distance(int(x),int(y)) here, since it is not a Livestream. I know the depth scale = 0.0010000000474974513.

[mnauf]

Does depth_image[int(cordinate[1])][int(cordinate[0])] * depth_scale give us distance in meters?

[mnauf]

But doing so gives me distance = 0.216 meters, even though the object was at least 2.1 meters away. Please note that I have already done on-chip calibration, so calibration shouldn't be an issue.

[mnauf]

This is what depth image looks like and this is how I read it:
cv2.imread(FILENAME, flags=cv2.IMREAD_ANYDEPTH)

[mnauf]

When I multiply this depth_scale with a Livestream depth image in example align-depth2color.py, it gives the correct distance, because depth_image values there aren't in between 0 to 255

[mnauf]

I had saved the depth_image by
cv2.imwrite(FILENAME, depth_image)

[MartyG-RealSense]

Hi @mnauf If you are not using get_distance then an alternative method of obtaining the real-world distance in meters is to multiply the raw pixel depth value uint16_t by the depth unit scale (which is 0.001 by default on the 400 Series camera models). There is a discussion about this subject at #7264

[mnauf]

@MartyG-RealSense Thanks. The issue was, my saved depth image values were in uint8, so I dumped them again using uint16, and then everything worked fine. You may close this issue now.

[MartyG-RealSense]

It's excellent to hear that you achieved a solution, @mnauf - thanks very much for the update! As you suggested, I will close this case. Thanks again!