Using dulling spray to defeat shiny objects?


(Andrew Gant) #1

Hello all!

Here is a fun one: Have you ever used dulling spray on a shiny object to get the kinect to register it? Obviously shooting shiny surfaces with the kinect does not work. My question is if using dulling spray on the object will allow the sensor to pick it up better?

For example, if you shoot a saxophone or shiny guitar, what can you do to make the surface readable?

Dulling spray is often used on set for objects that are too bright on screen and often become overexposed due to reflecting light. The spray will diffuse or dull the surface so that the light doesn’t bounce off as bright.


(Alexander Porter) #2

Yes! It works great. Anything that makes the surface matte rather than shiny will help with essentially any depth sensor you want to use.

Production dulling spray like Krylon is great because it wipes off easily and won’t ruin your saxophone. But any matte spraypaint clear or colored will work just as well for objects that are less precious.

There are three major kinds of depth sensors – Time of Flight, Structured Light and Passive/Stereo. Making a surface matte will help for slightly different reasons:

  • Time of Flight Sensors | Kinect V2 (supported), PMD Pico Flexx, Monstar sensors (not supported)
    These sensors work by transmitting pulses of infrared light out into the scene, measuring how long it takes the light to return to sense depth – like infrared sonar. They will benefit from matting/dulling spray because the light will bounce back to the sensor rather than somewhere else in the scene.

  • Structured Light Sensors | Kinect V1 (no longer supported), Asus Xtion 2 (not supported)
    These sensors work by projecting a pattern (often infrared) out into the scene and identifying how that pattern is distorted by the shape of the scene to sense depth. They will really benefit from matting/dulling spray because the projected pattern will be visible to the sensor if the surface is matte.

  • Stereo (Active or Passive) | Intel Realsense – Active Stereo (supported), ZED Camera – passive stereo (not supported)
    These approaches vary a little bit; a passive stereo sensor like the ZED will benefit slightly from a matte surface but it really needs feature points (dots, marks, surface details etc.) for it to sense depth, whereas an active stereo like the Realsense which projects features into the scene so would very much benefit from matteing/dulling for the same reasons as the structured light sensors.

We cover materials a bit in our documentation.