An example of a high accuracy point cloud that can be achieved with D415

[JTray]

Hi all,

It's a while since I have taken a look at the D415 so I decided to update to the latest firmware and see what improvements have been made as it wasn't accurate enough before. Ideally we need 1mm resolution I'm struggling to get a very clean point cloud (using the latest viewer + firmware). I have attached an image of something I am trying to scan. It's the silver piece in the image which is made up of different heights planes that we are trying to measure. Whatever setting I try I get a point cloud but it doesn't preserve any of the height detail in the piece. What am I doing wrong? I've changed the usual parameters like disparity shift, high accuracy mode etc but it's not helping a lot.

Is it possible for someone to share the best ply file they have managed to save out using the viewer. of a small part with 1mm type details visible. Is this possible with the D415 or any versions of the real sense sensors? (Spec says 1% of distance)

Thanks in advance

JT

[MartyG]

Have you tried changing the Depth Units, please? The default depth unit scale of the 400 Series is 1 mm. The older SR300 model has greater accuracy at very close range because its depth unit is set to only 1/32 of a millimeter (the trade-off is that the SR300 can see a much shorter distance than the 400 Series, though this is not a problem when doing short-range scanning). It is possible to alter the depth units of the 400 Series cameras to match that accuracy.

You can do a quick test in the RealSense Viewer to see if this will help you by expanding open the Advanced Controls > Depth Table option and using the Depth Units slider there.

[JTray]

Hi Marty,

Many thanks for the prompt reply.

I've tried that by setting it to it's lowest value of 100. It didn't help. I can't seem to find any setting that will give me any sort of detail we need. Am I chasing a unicorn or should it be possible?

Thanks in advance

JT

[MartyG]

If the metal is sufficiently shiny that it has reflections on it, that can degrade the image because it is harder for the camera to read areas that are reflecting light back. Covering the object with a fine spray-on powder such as baby or foot powder, or a professional reflection-damping spray, can help. Anti-reflection sprays are sometimes used for scanning 3D models of jewelry for use in catalogs.

Here is an example of a pro aerosol for 3D scanning:

https://www.laserdesign.com/3d-scan-spray/?language=en_US

Alternatively, change the position of the object so it has less reflection on its surface.

Grey or black objects may also be hard for the camera to read, because general physics principles mean that they can absorb light. For example, a user who once tried to scan a shirt with red and grey stripes captured the red stripes fine but had empty black areas where the grey stripes should be. Again, a spray-on powder coating can help with this.