What's a bump map?

Yep, I understand just enough to get by, and it can get confusing :slight_smile:

I would define bump mapping as a way of making lots of fine details without having to model it. It makes your object look bumpy without actually changing the shape of the object.

Say you want to model a piece of sandpaper. Your not going to model each and every little piece of sand. Since that’s impossibe you just use a texture as a bump map, examples of which have already been shown.

Hey, I have a question regarding this topic.
If I Unwrap an object, and Make a UV map in photoshop, is there any way for me to apply that to the object as a displacement?

Nevermind, I found a way:).

In case I wasnt the only one,
You Unwrap the object, paint the UV map (in grayscale), and the uv map as a image texture, then change map from too uv, and map to too disp and nor.

  				Originally Posted By [nyrathwiz](http://blenderartists.org/forum/member.php?u=12058)

With a Displacement map, the vertices are actually moved as per the texture map. But this means that the mesh has to have lots of vertices (generally done by doing a few levels of SubSurf) or the mesh will look like a tangled mess. This sends the polygon count through the roof.

So one uses Displacement maps when one doesn’t mind a large polygon count, otherwise use a Normal map.
Here is an example of a bump map. A sphere was subsurfed about four times, and the bump map shown was applied. The bump map was only 256x256 pixels. In the texture panel I hit the Disp button twice so it was yellow. This made it so the darker the map the more it was bumped
I just tried what you did on that sphere and it didn’t work like that at all
instead of making it look like your one it looked all wobly, anyone know why?

Could you post a shot of the render?

here is what happened http://www.oakhenge.co.nz/%7Ecraigms/cmd_img_20061024130500.jpg

not pretty is it?

You have displacement mapping enabled, in F5 buttons in the “Map To” pallet disable “Disp” and enable “Nor”. Nor = normal or bump. Disp = displacement.

No, he wants Disp mapping.

On mine, I have a UV sphere with 32 segments. It has the SubSurf modifier applied: Cadtmull-Clarke with 4 levels, 4 render levels, and the SubSurfUV button pushed. I think the entire sphere had the “Set Smooth” button pushed for it.

The sphere has one material applied to it. It has two textures.

Texture 1 is of type Image, using the scrap of texture map I supplied. The image has an X Repeat of 2 and a Y Repeat of 2. The texture has a MapInput of Orco and the Sphere button pushed. The MapTo has the Disp button pushed twice so it is yellow, the Nor slider is set to zero, and the Disp value is set to 0.2

Texture 2 is exactly the same except in MapTo the Col button is pushed and the Disp button is not.

Try that.

thanks for the walkthrough, it made it much better but it still came out all wobly and it seemed to stick out too far so I moved the disp slider down to 0.02 and this is what happened:
http://www.oakhenge.co.nz/%7Ecraigms/cmd_img_20061024173752.jpg
it’s still kinda shaky
it looks a bit like there is a cloud texture with normals on it but there isn’t

Ah, sorry about that.
The image I supplied was turned into a jpg file, which causes the cloud texture.
Try it with the png file here:
http://www.projectrho.com/misc/mecha2.png
You can also experiment with pushing the DISP button so it is pushed but not yellow, to see if you like that better. That controls whether a dark texture pushes the mesh inward or outward.

http://www.oakhenge.co.nz/%7Ecraigms/cmd_img_20061025104117.jpg
yay it worked
thanks so much for all that, I’ve never been able to get it to work properly before
so thanks

Good for you! It is a powerful tool in your Blender bag-of-tricks. You will note that my avatar is made from the same bump-map I gave you.

yeah I thought your avatar looked rather familiar.
thanks.