Residue after threshold filter like tail

sbilgi commented 3 years ago

Required Info
Camera Model	{D400 }
Firmware Version	(5.12.6)
Operating System & Version	{Linux (Ubuntu 14/16/17)
Platform	PC
SDK Version	{ l2.34.1}
Language	{C++ }

Issue Description

When I enable the threshold filter, there was residue like tail beside of moving object. What is the reason of this?

ezgif com-crop

MartyG-RealSense commented 3 years ago

Hi @sbilgi May I confirm please whether this is a 2D image or a 3D point cloud?

sbilgi commented 3 years ago

Hi @MartyG-RealSense, It's disparity map 2D, also occur in depth 2D map .

MartyG-RealSense commented 3 years ago

Having considered a range of possibilities, there are a few possibilities that I would consider most important right now:

That the problem is caused not by the humans but by the tiled floor pattern. RealSense 400 Series cameras can become confused when observing a repeating horizontal or vertical pattern such as a row of fence-posts (vertical) or window blinds (horizontal). The comment at the link below, and the comments below it, suggest resources that may help to reduce the problem.

https://github.com/IntelRealSense/librealsense/issues/6713#issuecomment-651114720

I note though that if you are using the threshold filter to remove the floor from the depth image then this may not be the cause.

Or that the legs are not being depth-detected clearly (due to the angle that the camera is at) as they swing back into the straight-down position, making them seem to appear and disappear as the humans stride the legs in front of the body and behind it.

This may tie in to the threshold filter values. If the camera has more difficulty with reading the current distance from the camera lens of the legs as they swing quickly then their measured depth values may momentarily go into a range beyond the maximum observable distance set in the filter, causing parts of the legs to be excluded momentarily from the depth image until their observed value returns below the maximum threshold.

dorodnic commented 3 years ago

Is temporal-filter also enabled? This looks like expected artifact of the temporal filter

MartyG-RealSense commented 3 years ago

Hi @sbilgi Do you still require assistance with this case, please? Thanks!

MartyG-RealSense commented 3 years ago

Case closed due to no further comments received.

IntelRealSense / librealsense

Residue after threshold filter like tail #7445

Issue Description