3: MAKING A UV MAP
There is no automatic way to create a nice UV
map for this object because of its complicated folding. My approach is
to first smooth out an Endomorph of the shape, tear it along seams that
will be hidden when rendered, roughly shape it into a ball and then create
a UV map with a spherical projection with that object. An Endomorph is
an extra set of 3D coordinats for each point in the model.
an endomorph click on the "M" button (next to the "W"
and "T" buttons at the lower right of Modeler's interface) and
then choose "(new)" from the pop up menu.
first step in making the UV map
To make a
spherical UV map I made a copy of the brain in a new layer. I used the
smooth command with a high settings. This smoothed the shape and allowed the
wrinkles to unfold.
can now be reshaped without affecting the base shape.
I used the "Smooth" command (near the bottom of the
"Modify" tab) to relax the shape so that I could see into the
It is very convenient that the wrinkles form hidden areas of
the model. I wanted to make sure that the UV map edges fall into some
wrinkles so that I will have one map that I can use to smoothly texture
the whole brain. To that end I tore the brain along some of the seams
and opened the tears up a little. To make the tear I first selected a
line of polygons along one edge of which I wanted to tear the model. I
cut these polygons out of the model.
I then used
either the "Move", "Magnet" or "Bend" tools
to move one side of the tear.
I then pasted
the polygons back into the model and used the "Merge points"
command to incorporate them again.
I then used the smooth command again, this time with Iterations
set to 1000
smoothed out the wrinkles:
I then used
the "Magnet" tool to reshape the brain into a rough sphere.
I also rotated the object so that the biggest tear faced along the -X
axis. This is because that is the direction Modeler putts the seam when
it creates a spherical UV map.
I then selected
the "T" button on the lower right of the window and then choose
"(new)" from the pop-up menu:
Here is the
resulting UV map after a little tweaking of some edge points:
the map as an EPS file and used it as a template to make bump and image
maps for the brain. The advantage of this is that I can texture the cortex
with one image. The disadvantage is that the wrinkles take up a lot of
space in the map. Only the lighter color areas on the map below will be
visible on the surface when rendered. I have to use very high resolution
images if I want small details to be visible.
I still have
a lot to do: Make the mid-brain spine arteries.