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Inconsistent depth using D435i

AEvdo2
Beginner
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Is this OK to have such a bad accuracy with D435i?

 

Measurements are changing like crazy with 5cm difference on 1.5m distance. I'd tried to calibrate my camera several times but this didn't help. Can I do something to get better measurements?

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MartyG
Honored Contributor III
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MartyG
Honored Contributor III
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It is worth mentioning that you should also calibrate the IMU component of the D435i using a separate process if you have not done so already.

 

https://www.intel.com/content/www/us/en/support/articles/000032303/emerging-technologies/intel-realsense-technology.html

 

Looking at your provided video, it looks to me as though the depth value is changing based on where you are moving the mouse's cursor arrow to on the image, displaying the depth at the coordinates that the cursor is currently pointing at.

 

For example, when you point the arrow at the table in front of the chair, the measured depth value is lower because that point is closer to the camera. When you move the cursor outside of the window, the depth value stops updating until the cursor returns inside the window.

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AEvdo2
Beginner
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Look at depth value while mouse cursor is staying at one point (0:05-0:06). It is floating from 1.65 to 1.68 m.

 

This is visualization of the point cloud from D435i of my room walls and door. Distance is approx. 3m. Flat surface looks like storm sea.

Is it supposed to be so wavy? Door.png

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MartyG
Honored Contributor III
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Okay, I went through the video frame by frame and see what you mean about the range of change whilst that mouse is sitting still on that particular point.

 

The fact that the waves are primarily on flat surfaces such as the walls and doors makes me think that they are being generated by a semi-random pattern of dots being projected onto the room scene by the camera's IR Projector component. This projected pattern can help the camera to read texture detail on flat, low-texture surfaces. The projection can be turned off if you do not want to use it.

 

The image below is an example of a RealSense user projecting a dot pattern onto flat walls from an external LED-based projector.

 

1.png

 

May I please also ask whether you are using fluorescent lights such as ceiling strip-lights in the location where the camera is? These can cause disruption to the camera image because the heated gas inside them causes them to flicker at frequencies hard to see with the human eye. If you are currently streaming at 30 FPS, using 60 FPS has helped improve the image for some people, because the FPS is operating closer to the frequency of their particular fluorescent lights. Others who were having problems with their image under fluorescent lights at 60 FPS conversely found that it improved when running at 30 FPS with their particular lights.

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AEvdo2
Beginner
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Setting emitter off didn't help.

 

Those yesterday pictures was taken under sunlight, no other lights were on.

 

Can this be a device issue?

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MartyG
Honored Contributor III
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Is there any change if you turn the Auto Exposure setting off?

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AEvdo2
Beginner
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Yep, with certain exposure value I've achieved slightly better consistency but not as much as I want.

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MartyG
Honored Contributor III
501 Views
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