The job of the bumpmap generator node is to apply a heightmap (grayscale
bump image) to the object's topology and to calculate a new set of
normals based on the combination of heightmap and geometry. The result
is a normal map in object space, you can display it when plugging the
output of the bumpmap generator directly into the surface input of the
material node. This conversion from heightmap to normal map is essential
to make the effect work correctly and cannot be provided through the
image node when plugged to a material's bump input.
The image node, however, features a bump switch, which creates the
normal information just as the bumpmap generator does, but it only gets
carried along with the image node's regular colour output under the
hood, not visible as a connection in the rendertree. Workflow would be
to block out the colour of the heightmap image using a mixer node and
connecting the mixer to the shader's diffuse and ambient inputs. This
way the bump information is used during rendering without display of the
heightmap on the object's surface. Ugly. Basically how it used to work
in SI3d, if I'm not mistaken...
Cheers!
-André
Morten Bartholdy wrote:
Well I never used camera projection for bumpmaps so it is not exactly
part of my workflow. i usually use Zbump or plug BA shaders directly
into the Surface bump input, and almost never use surface shader bump
inputs. Forgive my ignorance - I didn't know it would produce wrong
results this way - could you enlighten me?
Morten Bartholdy
3D & VFX Artist
----- Original Message ----- From: "André Adam" <a_adam(at)49games.de>
To: <XSI(at)Softimage.COM>
Sent: Thursday, December 07, 2006 11:37 AM
Subject: Re: Bump Mapping and Camera Projections?
Bah, bump mapping through image nodes is such an ugly thing to do.
Btw, you don't plug your image node directly into a bump input, do
you? That would give plain wrong results...
However, thanks for the feedback!
-André
Morten Bartholdy wrote:
I see the same thing here André - don't know if I'm doing it wrong
either though ;)
Workaround would be to plug your image node in to the bump input of
the surface shader. It limits your options but works.
Morten Bartholdy
3D & VFX Artist
----- Original Message ----- From: "André Adam" <a_adam(at)49games.de>
To: <xsi(at)Softimage.COM>
Sent: Wednesday, December 06, 2006 4:59 PM
Subject: Bump Mapping and Camera Projections?
Hi all,
I'm currently trying to reference a camera projection as a texture
space for a bumpmap generator node. Doesn't seem to work, at least
I can't spot any piece of bump mapping. If connected to an image
node, the texture appears on the object's surface as expected. Is
this some kind of limitation of the bumpmap generator node or is it
me doing something plain wrong?
Cheers for a quick hint!
-André
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