Greyscale bumpmap

[tradedaemon]

Quick question, to make a bump map of an image, don't you just convert the image fro color into grayscale and you have the bump map?

[artchick]

That'll do it....you may want to adjust the contrast to correspond with how much bump you want (more contrast for more defined bumps, less for more subtle bumps). Sometimes you may also want to invert the map, depending on the effect you're looking for.

[kuman]

hmm yes and no. for a quick fix you can definitely convert the map to gray scale, but for a better bump map you need to do more work. if you don't invert settings, in a gray scale bump map, black is zero height and white is maximum height. but sometimes you need to do more work to make a good bump map than just set a color map to gray. lets take tree bark for instance. if you look at most stock textures you'll see that there's dark areas and light areas, but those are most likely caused by lights and shadows (which is why the more angularly lit a texture is the less usable it is). you'll see that the dark areas are not the recessions in the bark but the shadows that were cast. in a well crafted bump map for bark, the dark areas would be the areas around the knobby extrusions and the light areas would be where the bark sticks out.

it may seem fairly trivial if you're just looking for some kind of surface property that will break up the lighting but if you're trying to make a lead character or a lead vehicle or what not, its a good idea to take the time to paint a good bump map, its the difference between someone that's throw together or a polished peice. if you make it well it can also be used for displacement if you later use a subpixel displacement enabled renderer, and you'll be able to get the sillouette from the bump too. if possible though its always good to have a good bump map, this is especially true for low poly work with today's real time engines that enable bump mapping. in low poly you don't have a lot of geometry to work with so its wise to squeeze out every bit of detail in texturing that's possible.

-k

[artchick]

Good points, Ku:)

[tradedaemon]

K thnks,

[sjdragonfly]

bump maps are an integral part of texturing! I'm cringing right now at the thought of just turning a color map into grayscale for the bump...my specialty is texturing, so I guess that's why I feel that way.

There's a great book by Bill Fleming that you should check out to see the glory of the bump map. It's called "Freaky Frank...something about Hollywood Creature Textures". I learned so much from it.

I'll try and post some maps for you after I get home so you can see the reason for the special attention to the bump. That's the one I spend the most time on and the color is usually just secondary if you can make a good enough bump. It just takes a lot of practice.