Build a Well in
Carrara and UVMapper Pro
Carl E. Schou
February 28, 2003
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Wendigo Well
For this month's foray into the
digital domain, we are going to use UVMapper Pro and Carrara
Studio 2 to build a 3D model of a stone well using displacement
mapping and Boolean subtraction techniques. If you don't
have UVMapper Pro, you can also do the displacement mapping using
the Anything Grooves plug-in for Carrara, though this tutorial
will focus on using UVMapper Pro. Links for both of these
utilities are provided at the end of this tutorial. |
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Some Background on
Displacement Mapping
At a distance, the results of
displacement mapping look very similar to the effects of a bump
map. Bump mapping causes the light reaching an object to
behave as though the smooth surface was really irregular,
creating shadows and the illusion of surface depth.
Displacement mapping actually transforms the smooth surface of the
mapped object, creating real depth and shadows.
Displacement mapping is the process
of changing the shape of a mesh by applying an image to the mesh
and using the image as a height map. The dark areas of the image cause the mesh to sink in
towards the center of the object. The light areas cause the
mesh to expand out away from its center.
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Strategy for
Building a Well
(1) Produce a tiled image of a stone
wall.
(2) Apply the image as a displacement
map to a cylinder using UVMapper Pro.
(3) Use Carrara to duplicate the cylinder, making
the duplicate a little smaller, and set slightly inside the
original cylinder.
(4) Boolean subtract the smaller
cylinder from the larger one to generate a new mesh. |
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Make the Tiled
Source Image
For source material, a simple image
of a stone wall will do, though a seam will occur in your model at
the place where the two side edges of your texture join when
wrapped around the cylinder. To avoid this problem, we will
make a seamless tile of the image.
For source material, I used the image
of the stone wall of the museum in the park where I frequently go
hiking.
The image was tiled using the Texture
Resynthesis module that is included in the Texture Maker program. Texture
Maker is a program specifically designed for seamless texture
generation. The Texture Resynthesis module works by
analyzing the structure of a small sample of an image and
synthesizing a tiled version of that image. A link for the
Texture Maker program is given at the end of this tutorial. The original
image of the wall is shown below left and the tiled image is shown
below right. |
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Build a Stone
Cylinder in UVMapper Pro
Now we re going to create a cylinder
in UVMapper Pro and use our image as a height displacement map. Start
up UVMapper Pro and click on File>NewModel>Cylinder.
Set the number of sides and the height divisions to 128 to get a
medium resolution cylinder. Click on View>ShowModel to
see the cylinder. Next, click on Texture>Load and
select the BMP file that will be used for the displacement
map. Click on Tools>Vertices>Displace. Use a
MinOffset of 0.0 and MaxOffset of 0.25 to set the height
displacement. You should see something like the image
below. Try experimenting with different settings for
cylinder resolution and height displacement to see the effects on
the cylinder. When you are satisfied with the results, save
the model as an OBJ file. |
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Make the
Stone Cylinder into a Well in Carrara
Start up Carrara and import the stone
cylinder you just produced in UVMapper. You should see
something like the image below. |
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Duplicate the
cylinder, then resize it to 80% along the X and Y axes. Move
the new cylinder up by 2 units in the Z direction as shown in the
image below. |
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Now we're
going to hollow out the well using Boolean operations.
Select both objects, then click Edit>3D Boolean and subtract the smaller
cylinder from the larger one. This process will take a while
because it is very computationally intense. Depending on
your machine, you may just want to let this part run
overnight. The good thing
is that Carrara actually generates a new mesh out of the Boolean
operation. Most other 3D apps would not produce a new mesh,
so you would be in trouble if you wanted to export your model into
another program. When the process is complete, you should
see something like the image below. |
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Texturing the
Well
The beauty of this type of modeling
is that the model is already UV mapped to accept he texture that
was used to generate it. Simply apply the original tiled
image to the well using parametric mapping. Add a small
amount of high frequency noise to the bump channel and you should
get some very realistic results.
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The Rest of
the Picture
The bones were built using Organica
and the toadstools were done in Amorphium Pro. The ground
was a Bryce terrain built using a tiled image of pine needles for
a height map. The Hemlock trees were made using the Bryce 5
TreeLab. The final image was rendered in Bryce using the
Soft Shadows option.
The Wendigo is a creature out of
Native American folklore that few people would like to meet.
Fortunately, he was not at home when this rendering was made. |
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Copyright © 2003,
Carl E Schou, All Rights Reserved |