Depth map of a flat surface with D415
Hello,
Since a few months ago we are working with the d415, so we have already get experimental knowledge about its performance. But we have still a doubt/issue that I need to ask you. When measuring a flat surface (white matte, and so we work with the IR emitter ON) the 3D result has the shape of a (lets say) residual pattern. For example when working distance from the d415 to the flat surface is around 300 mm, the 3D measurement is as follows, with a peak-to-valley depth of around 6mm. This is also observed at other working distances (0.5 m, 1 m, etc.) :
In the documentation I have read that accuracy with the 400 Series cameras is typically around 2% of the distance. This seems in agreement with the aforementioned example, around 6 mm peak-to-valley that i am getting at 300 mm distance. But, despite the accuracy error might be in accordance with the cam performance specs, I would like to know if there is any way to correct this (lets say) residual pattern or not?.
This depth map of the d415 is in accordance with the expected cam performance?, or we are missing something that can improve results?.
Thanks.
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Hi Miguel Ares If the surface that the camera is observing is flat and has low texture or no texture (like the white wall that your camera is pointed at) then turning off the IR emitter may indeed not be a suitable course of action. This is because the projection of dots onto a surface provides texture for the camera to analyze for depth information. 400 Series cameras can alternatively use ambient light in a well-lit scene to obtain depth information in the absence of a dot pattern, but this may not be practical for a textureless surface.
You could consider using an external LED pattern projector to project a dot pattern instead of the built-in laser projector of the camera. The camera's laser-based projector can cause a noise effect on the image called laser speckle. A dot pattern cast by an LED projector will produce significantly less speckle. Intel have a white-paper document about use of projectors with 400 Series cameras at the link below.
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