Log in

No account? Create an account
Depth and reflectance map auto-capture with two photos - one with flash, one without. - Adventures in Engineering — LiveJournal
The wanderings of a modern ronin.

Ben Cantrick
  Date: 2008-08-27 22:31
  Subject:   Depth and reflectance map auto-capture with two photos - one with flash, one without.
  Tags:  slashdot

First an image of a surface is captured without flash. Portions of the surface that are higher appear brighter, and portions that are deeper appear darker. The problem is that the different colors of a surface also reflect light differently, making it difficult to determine if the brightness difference is a function of depth or color. By taking a second photo with flash, however, the accurate colors of all visible portions of the surface can be captured. The two captured images essentially become a reflectance map (albedo) and a depth map (height field).

"Software then compares the brightness of every matching pair of pixels in the two images and calculates how much of a pixel's brightness is down to its position, and how much is due to its colour. That information is used to produce a realistic rendering of a surface's texture."



There's a video demonstrating the technique - quite impressive. This quick, cheap capture technique should drive a whole new level of realism in video games.
Post A Comment | 2 Comments | | Link

Alex Belits
  User: abelits
  Date: 2008-08-29 00:03 (UTC)
  Subject:   (no subject)
I wouldn't call it true 3D capture, more like un-bump-mapping surfaces. Complex shapes, light sources in unexpected positions, shades, etc. can cause all kinds of unpredictable effects that would be avoided with plain stereo images capture, though just like model + texture + bump mapping provides more detailed-looking object, flash plus stereo images can get more detailed information about the surfaces (though not their absolute positions) usable for the same bump mapping.

And, of course, the obligatory image with flash:

Reply | Thread | Link

  User: ohmisunao
  Date: 2008-08-29 01:19 (UTC)
  Subject:   (no subject)
I'm not sure this technique will revolutionize texturing for games or otherwise.. it's too limited and inaccurate for that IMO. The side by side comparison of a laser scan vs. this flash technique is almost night and day different (the laser scan looks way better).

A lot of normal mapping in games has to be created from a 3D surface also because of the lighting requirements.. so accurate displacement or geometry is required.

I think this might be a good work around for quick results or testing though.
Reply | Thread | Link

May 2015