PART 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.

To create 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.

 

The 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.

The Endomorph can now be reshaped without affecting the base shape.

STEP 21

I used the "Smooth" command (near the bottom of the "Modify" tab) to relax the shape so that I could see into the wrinkles.

The smoothed shape:

STEP 22

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.

The torn up model:

STEP 22

I then used the smooth command again, this time with Iterations set to 1000

 

This completely 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:

I exported 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.

The bump map:

The textured cortex:

I still have a lot to do: Make the mid-brain spine arteries.

-Joe