Friday, August 28, 2009

Two Warnings About Normal Maps

Two warnings about normal maps:
  1. Make sure that the RGB color underneath transparent sections does not turn black or white! Some image editing programs (in particular Photoshop) will lose the color beneath a transparent area.

    With a normal map, this is very bad - black and white are not legitimate normal map colors, and the result will be bogus normal vectors under the non-shiny part. Normal maps affect more than just specular shiny hilights - the normal map affects all lighting, so having black or white under your transparent (non-shiny) parts is bad news.

    To check whether this has happened, I recommend Graphics Converter, which will show you your alpha and RGB channels separately, exactly as they are in the file.

  2. Make sure your RGB value are normalized. The "length" of the normal (as encoded in RGB) must come out to a distance of 1. This is virtually impossible to do using PhotoShop or an image-oriented program...I suggest you use a real plugin to PhotoShop or Blender to create normal maps that are correctly "normalized".

It is also very possible that X-Plane's gamma correction is distorting normal maps, but that's one for me to fix.


Steve said...

Since I'm a big photoshop fan, I know I'll be doing my normal maps there. Nvidia has a free PS plugin: Can't vouch for it yet, but there it is for all to try.

Anonymous said...

(Off-topic) I just have to say THANK YOU for moving Austin's 9.31 what's new changes from the front page to its own separate little page. It was totally crapping up the professional look of the new site.

However it's still pretty ugly, centered text for an entire page? Seriously guys...Please get Austin into the habit of using a real blog!