Results 1 to 5 of 5

Thread: Common misunderstanding with bump/height maps?

  1. #1
    Intermediate User Shloime's Avatar
    Join Date
    Sep 2003
    Location
    Germany
    Posts
    103

    Common misunderstanding with bump/height maps?

    Hi.
    Since years I'm wondering about bump/height maps, which are provided in some packages offered free and also in some sold texture packages.
    I attached a few pics to explain my point, but this is my question in short:
    In a bump map (same goes for so called height maps, and even displacement maps, which are all basically the same in my opinion) the altitude of the surface is represented in gray scales translated into percent, right?
    So black is 0% and white is 100%, mostly translated by 3d-packages as 0 being the lowest point and 100 being the highest one. As an example, a bump map for a golfball would be an overall gray with circles in a somewhat darker gray for the dents on the ball, maybe with a gradient to the middle of the circles to make the dents getting deeper to the middle.
    Most bump maps delivered in quite some professional texture collections are just a grayscale image of the color map, and thus carry some completely different information. It is not altitude, but brightness of the surface, being even worse, when the color map is not neutral but contains lighting information with shadows and stuff.

    Same goes for most other maps, like roughness, specular etc. A lot of times they are just grayscaled versions of the color map, and to look different, they are sometimes just inverted. This is not at all the information I expect in these maps.

    Take a look at the pictures and try to understand my point, and feel free to ask questions before beginning a flame war.

    Click image for larger version. 

Name:	01diff.jpg 
Views:	38 
Size:	434.4 KB 
ID:	145408Click image for larger version. 

Name:	02rough.jpg 
Views:	41 
Size:	280.5 KB 
ID:	145409Click image for larger version. 

Name:	03spec.jpg 
Views:	37 
Size:	296.7 KB 
ID:	145410Click image for larger version. 

Name:	04bump.jpg 
Views:	33 
Size:	320.1 KB 
ID:	145411Click image for larger version. 

Name:	05conclusion.jpg 
Views:	32 
Size:	199.9 KB 
ID:	145412

    Just for information: I'm into 3D software since the days of VideoScape and Sculpt 3D, and started LW beginning with V3.5 on Amiga. So I consider myself somewhat experienced.
    Greetings, Shloime
    ----------------------------
    Win10 64, Ryzen 5 1600, GTX 980 ti, 32 GB, LW 2018

  2. #2
    hi,

    check out tools like:

    https://github.com/kmkolasinski/AwesomeBump

    its not 100% perfect, but it can provide you with a starting point in creating somewhat believeable bump / normal maps
    (there are also some youtube vids on this)

    of course you can go the full length, by building a pbr scanner like this one
    http://rtgfx.com/pbr-texture-scanner/
    or photoscan your texture and extract the maps from the resulting mesh.

    Sites like poliigon do have soem handcrafted / scanned textures.

  3. #3
    Intermediate User Shloime's Avatar
    Join Date
    Sep 2003
    Location
    Germany
    Posts
    103
    Hey, I just noticed we joined the forum at the same time

    Thanks for the links and the more or less hidden confirmation to my observation.
    I guess I can't find the time and patience to build this interesting tool.
    Actually I just wanted to find out if I am totally mistaken or if those mentioned texture collections are really not that perfect.
    Marander answered in another thread and confirmed it, too, so with this knowledge I can sleep better tonight.
    Greetings, Shloime
    ----------------------------
    Win10 64, Ryzen 5 1600, GTX 980 ti, 32 GB, LW 2018

  4. #4
    Curmudgeon in Training Ma3rk's Avatar
    Join Date
    Mar 2003
    Location
    Near Beaverton, OR
    Posts
    1,354
    Quote Originally Posted by Shloime View Post

    So black is 0% and white is 100%, mostly translated by 3d-packages as 0 being the lowest point and 100 being the highest one.
    I believe Lightwave uses, or at least used to use, a middle gray as it's zero point for Bump rather than the 0-100% model.
    "Never be a cat in a cartoon. Never." Chief Wiggum

  5. #5
    Intermediate User Shloime's Avatar
    Join Date
    Sep 2003
    Location
    Germany
    Posts
    103
    Ma3rk, good point, and you are absolutely right. If you look at my fifth picture, I made the base level medium gray, so there would be some levels left to go lower, like dents and scratches.
    For the point I tried to make the 0 to 100% model seemed good enough, though. And it is true for spec and roughness maps, which are a lot of times also made in a less than perfect way.
    Greetings, Shloime
    ----------------------------
    Win10 64, Ryzen 5 1600, GTX 980 ti, 32 GB, LW 2018

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •