bump maps? (image included, is this right?)

What is a bump map and how would I use one?

Bump tut

Wow, thanks for the quick reply (one minute)

Okay, so it makes the surface bumpy. How does blender decide what goes in and what goes out?

Black stays neutral and white takes the full value unless you press Nor twice in which case the two are reversed.

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Okay, but what about other colours?

They are all an intermediate value between 0,0,0 (black) and 1,1,1 (white).

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Thanks, seems like most of my technical questions are answered by you Fligh % :smiley:

I have a problem with bump map: I am doing a a bridge and activated normal mapping as usual, but it doesn’t work. On this thread you can see an image and download the .blend file. If you go there please reply.

When I subdivide my model loads, then it works. Is there a way that I dont need like 1000000 verts per face?

Are you asking about displacement maps or bump maps?
The advantage of bumpmapping is that with just a few vertices, you can create an (cheap) illusion of a highres detailed surface. But with displacement, you are really taking the vertices and push them around according to the map, and that is why your model need to be dense, so it can keep up with the resolution of the map. This is brute force, and you really want a simple model, so check again if your image is not mapped to DISP instead of NOR

Which one do I want to use?
I have a plane (4 verts) for the ground and I want to add a gravel texture to it. Can I make this happen with nor or disp?

On a simple plane, you would make a gravelly texture with Nor (bump) mapping. It only simulates the changes in lighting coming off a bumpy surface. The surface geometry (vertex coordinates) are not changed. You can see this if you look at the edges of the plane; they stay straight.

Disp(lacement) mapping won’t work on your 4 verts, because this type of mapping tries to actually change the mesh geometry (as if you had modeled every piece of gravel). For this reason Disp mapping works best on highly subdivided meshes.

Blender Wiki is getting very good on this topic:

http://mediawiki.blender.org/index.php/Manual/PartIV

So basically I get the same result whether I map to nor or col?

No, a Normal map changes the direction of surface normals in rendering, so you get a pseudo-relief look. Also a texture mapped only to Nor doesn’t change diffuse color.

Procedural color maps preserve normals’ directions so don’t create the illusion of bumps; they only affect the diffuse color.

It begins to make sense.
So basically nor ‘fakes’ disp
Is disp the same as noise then, but noise taking place before rendering?

Is disp the same as noise then, but noise taking place before rendering?

Yes, you could say that, although there are still differences (mapping in texture space vs. object). The final rendered effects are similar.

Goto Google and enter as search term:

Define: bump mapping

After “Define:” you can use any technical term eg, “Displacement Mapping”, “Refraction” “Z_Buffer” etc… Blender may use different names eg, BumpMapping instead of NormalMapping but you’ll still find most, if not all, of what you’re looking for.

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Still need help.

Or wikipedia. Try this