Bump maps

[The Hogfather]

I've made a bump map but when apply it to the cube that forms the walls of my room it only seems to render on 1 wall.

[kbrown]

I can think of two possibilities:
- UVs are not properly mapped
- The normals of the other wall are inverted

[Pony]

also render from a difrent angle. Bumpmaps don't aways do well at all angles.

[The Hogfather]

Thanks for the advice guys will give it a go.
:D

[NNY Design]

sorry but i dont get the whole "bump map" thing sorry if its dumb but.....

[Alan]

a bump map simply alters the direction of the normal (based on a greyscale image/texture) to make it look as though it is lit differently. Displacement is the exact same except that it actually moves the point along the said normal by the calculated displacement.

check this
http://www.alanwoods.co.uk/personalresearch/colourMaps.htm#Bump

Alan

[The Hogfather]

Cheers pony it did seem to be the angles I'm rendering at to test the bump map. Maybe I should mess about more before screaming at my comp and posting here. :D

[NNY Design]

i see but how can i make my own bump map out of the image i am using as a texture?

Chris

[The Hogfather]

You can make a black and white image that will tell maya the areas of the texture to bump map. Here is an example of the bump map i used for the wall. I should make things clearer for people who are new to bump maps.

[Alan]

that's not a great example ;) the bump map should really be inverted as the white areas are raised and the black ones lowered (with grey representing the area inbetween)

Look at the link on my site (posted above) it's a better more elegant version :)
Alan

[NNY Design]

I have tried some things in phtoshop and i cant seem to get it the black on white good like :rolleyes: that what shall i do?

Thanks, Chris

[Clod]

It's not just black and white.
Start with a greyscale image with red, green and blue at 128.

Then lighten the areas you want raised and darken the areas you want lowered. If you want to see the changes as you make them, have the bump map open in the attribute editor and click "Reload file texture" when you make changes (and save them) in photoshop.

[mtmckinley]

As far as I've seen, bump maps do tend to be just greyscale. Not that color maps won't work, but greyscale gives you the most accurate result, I think.

[Clod]

That's what I meant Mike, I probably didn't make myself clear enough. By "not just black and white" I meant different tones of grey. I usually just create a 24 bit image and flood it with 128 in R,G,B, grey rather than creating a greyscale. Same thing.

Edit: actually not the same thing, a pure greyscale would use much less memory.