Question about Dirt?

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  03 March 2005
Unhappy Question about Dirt?

Does anyone really know how to use this plugin? I have a model that
has a good UV setup(no overlaying polygins). But to texture the model,
I have 3 textures that are applied to different portions of the model.
Two are cylindrical and one is cubic projection. I have tried to use the
Vertex Map, no luck. I've tried to create a image map, for the diffusion,
but have no idea how to reapply it. I don't have a UVW mapped texture
on the model. I've even tried to bake the diffusion channel, but this
doesn't produce anything usable.

My last test was to create a new material with just a diffusion channel
and then put the dirt image on this and then mix textures, but this
resulted in no dirt.

Any ideas? I'm totally lost.

Mark
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  03 March 2005
I don't know why you aren't getting dirt without seeing the model, but keep in mind that its placement is calculated by looking for surfaces that that are enclosed by other surfaces (like crevaces). A sphere, for example, would not have any dirt because its surface is not enclosed by any other surfaces. A Tube, on the other hand, would have dirt in the center. Don't forget to check the dirt channel's ray bias, spread, etc...
 
  03 March 2005
Originally Posted by WayneZacMP: I don't know why you aren't getting dirt without seeing the model, but keep in mind that its placement is calculated by looking for surfaces that that are enclosed by other surfaces (like crevaces). A sphere, for example, would not have any dirt because its surface is not enclosed by any other surfaces. A Tube, on the other hand, would have dirt in the center. Don't forget to check the dirt channel's ray bias, spread, etc...


Thanks for the help, but I understand how the dirt is calculated.
The trouble I'm having is how to apply it to the model. According to the manual you
can't just put the DIRT effect in the duffision channel for animations.
(I think this causes flickering).

So I'm trying to figure out how to use the Vertex or Image map when I don't have
a texture assigned to the model that is not UVW mapped. All my assigned textures
are limited to polygon selections and are either cyclindrical or cuibic mapped.

Arrgg...

Mark
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  03 March 2005
Out of curiosity... what is the vertex shader giving you.
 
  03 March 2005
While the dirt function would give better results, I have found the regular dirt (loaded into the difuse or even color channel of a material) to work quite well, and fast to set up. I used it last night for some pre-lim renders interior that I have not set up any specific lighting for. I just have one omni set to no shadows and ambient, then multi-select most of the materials and load the shader into diffuse. Better results by using different setting for different parts, but a the all-at-once id quick.

I like a gritty look. I have found the best results with the bias set to 0! is also good, but for some reason 0 seems best. Then the rays number goes from grit to smooth, I stay in the 75 range for some grain.
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Acme Digital
 
  03 March 2005
Originally Posted by wesware: Out of curiosity... what is the vertex shader giving you.


Wes,
When I calculate the Vertex map, it is placed on the object with the name "Dirt Map".
The manual says to then load the Dirt effect into the channel and all will be well. However,
the dirt generated looks the same regardless of whether I have the "Dirt" vertex map
or not. Do then I tried loading the vertex map into the diffusion channel and nothing
happens there.
As for the vertex map, it does show some color change at appropriate spots, but
nothing like I expected.

To recap:
If I just put the dirt effect into the diffusion channel of my shader(used only on some
polygons) the dirt looks great.

If I try to load a vertex map generated be the "caculate dirt" command, nothing happens.

If I create a image map for the dirt, the image looks great, but I don't know how to
apply it because my textures for the cover only the parts that they were designed for.


I'm open to any ideas on how to to this... :-)

Thanks

Mark
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Wishing I was in the Carribean!!
 
  03 March 2005
I remember reading somewhere that dirtmaps have to be calculated spherically. I think I also remember that the questioner was pleased and got it working right..

best
BT
 
  03 March 2005
never had any problems with vertex maps caculated by Dirt....

Quote: As for the vertex map, it does show some color change at appropriate spots, but


the look of your vertex map will depend on density of the mesh - on a very low-poly mesh you'll get a few spots, on denser, even mesh results are much better.

Quote: When I calculate the Vertex map, it is placed on the object with the name "Dirt Map".
The manual says to then load the Dirt effect into the channel and all will be well. However,
the dirt generated looks the same regardless of whether I have the "Dirt" vertex map
or not. Do then I tried loading the vertex map into the diffusion channel and nothing
happens there.


if you have the dirt map generated, you don't need the dirt shader - just apply the Vertex Map shader (for example in diffusion slot), and drag the dirt map into it. That's the whole point, to bake the dirt into a vertex map, to avoid using dirt shader and flickering.
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  03 March 2005
Wink

Originally Posted by azazel: never had any problems with vertex maps caculated by Dirt....


if you have the dirt map generated, you don't need the dirt shader - just apply the Vertex Map shader (for example in diffusion slot), and drag the dirt map into it. That's the whole point, to bake the dirt into a vertex map, to avoid using dirt shader and flickering.


Ahh.... Thanks for clearing this up. According to the manual it says that after the vertext
map is generated, that you just put the dirt shader into the diffusion channel. I
was always confused by this, because I didn't understand the reason for creating the
vertex map if you are going to apply the dirt shader anyway. Thanks for the clarification.

Also, this is a low poly model(until hypernurbs) so I guess the vertex map won't
be that good. Oh well... Off to try and figure out how to use the image map.

Thanks a bug for the help.

Mark
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Wishing I was in the Carribean!!
 
  03 March 2005
Lowpoly before Hypernurbs is sometimes enough to generate dirt - it realy depends on the mesh.
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  03 March 2005
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