Hi all, I have been struggling learning the difference between bumpmapping and normalmapping for awhile now so I decided maybe someone here can better explain it to me. Is bumpmapping a texture that has tangent space offset vectors? So to implement bumpmapping would be to add vertex normals to all the verticies in your mesh. Then, in your shader, transform the vertex normals to tangent space. And finally, add the tangent space offset vectors that are in the bump map texture to the transformed vertex normal? Is normalmapping a texture that has the base normals? So to implement this, in your shader you look up the normal in the normalmap texture given vertex UV coordinates thus you don't need to have vertex normals? Those words are used so interchangeably that I get confused very easily when I read about either one. Also, I have a mesh of a person's face but I only have position and UV coordinates for each vertex. I also have a diffuse texture of the person's face. I was wondering if there was a way to generate the base normals (not offsets, since I don't have any base normals) from the diffuse texture. I'm pretty sure there are tools (e.g. nvidia's normalmapping photoshop plugin) that do this but since bumpmapping and normalmapping have me confused, I'm not sure if a certain tool does what I want. Thanks for any help! :)

You always need vertex normals. Normal-maps are in tangent-space, and dependent on the vertex-normals. Bumpmaps and normalmaps are the same thing.. though sometimes bumpmap is used to describe a black and white heightmap texture, while normalmap is the texture containing the normal directions.

Thanks for the reply Erik

So a normalmap/bumpmap is just a texture that has tangent space normal offset vectors?

Also, if you always need vertex normals like you mention, then to get unfaceted (smooth) looking meshes, you have to use weld/smoothing group techniques? I know how to use weld/smoothing groups in 3ds max to get a mesh to look smooth but when I heard of normalmapping, I figured it was a way get around welding/smoothing groups and by just using a texture lookup. But then I couldn't figure out how to generate the normals from a diffuse texture which as it sounds, maybe impossible if you always need vertex normals.

Bump Mapping means perturbing the surface properties (usually just the normal) at per-pixel level according to some textures, to simulate bumps or rough material imperfections.

Normal Mapping is the simplest form of Bump Mapping.

There exist more complex ways to implement bump mapping, which achieve greater results, for example Parallax Mapping and Relief Mapping.

Nowadays normal mapping is the entry-level bump mapping, and every engine has it. Parallax mapping is widely used because it increments the grade of realism without slowing the shader too much. Relief mapping, and Cone Mapping, lead to almost perfect results but are kinda slow.

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The bump map is a texture which defines the height of the elements.
The normal map is derived from the bump map, and specify only the normals of the elements (not the height anymore).

Normal Mapping requires only the normal map.

Parallax, Relief and Cone mapping, require both the maps.

Usually, the normals in the normal map are stored in tangent space, which is the better way to store normals in order to obain scalability and indipendence from the formats.

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To implement normal map, you have to save the tangent base at each vertex, and then interpolate it.
Tangent space means normal, tangent and bitangent vectors of the vertex.
However, it's suggested to compute either the tangent or the bitangent at shader level, to decrease the amount of memory required, so the band.

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hope it helps ;)

Thanks for all the replies.

Now I think I get it.

So bumpmapping and techniques to implement it (normal/parallax/relief) are all ways to perturb the surface (make it look bumpy). But you always have to save some sort of base normal per vertex (in tangent space, or model space) and with bumpmapping techniques you can perturb this base normal per vertex which makes your mesh look bumpy.

Quote:Original post by link3978
with bumpmapping techniques you can perturb this base normal per vertex which makes your mesh look bumpy.

better, you take this normal and interpolate it through all the fragments. Once here, at fragment level, you use your bump-data (that can be the new normal, or also the "height" of the fragment) to compute the light values.