PART 3: TEXTURING THE HEART
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Texturing such a complicated shape in Lightwave is challenging. I decided to create a spherical UV map of the main section of the heart, because it is roughly a round shape. The large veins and arteries on the upper part of the heart are textured with a flat color and a procedural bump map.

STEP 1
I hid the upper tubes coming out of the heart. I then created a new spherical UV texture for the bottom section of the heart. This is done by clicking on the "T" button at the lower right of the Modeler window and then choosing "New UV map" from the popup menu next to the button.

STEP 2
Because of the complicated shape of the heart, there are some overlapping polygons in the UV map. To fix this I moved some of the points in the UV map around to remove the overlap and also to make the map fit the UV space exactly. This image shows the original map in the background and the adjusted map in the foreground layer.

STEP 3
Next I needed a guide image that showed were the modeled arteries intersected the surface of the heart, so that I could paint color and bump maps that matched the arteries. I copied the heart to a new layer and subdivided it. I made this guide image by using the Solid Drill command to drill the shape of the arteries into the copy of the heart. This image shows a subdivided copy of the heart with the 3D veins in a background layer. I have just used the solid Drill command to stencil the veins onto the heart.

This operation also cuts the UV map, showing where the arteries fall on the UV map. I exported the UV map as an EPS file and used the EPS file in Photoshop and Illustrator as a guide for creating the textures

STEP 4
This images below shows a section of the color and bump maps. I painted a layer of fat around the arteries. On top I painted smaller arteries branching off from the modeled ones.

STEP 5
I also made a mask texture to blend between the UV texture and the base color of the heart. Here I have loaded the mask as a backdrop to the UV map. The black areas are the holes in the map where the large tubes connect to the main body of the heart.

STEP 6
This examples shows how the color texture map is applied to the heart. Although the idea is simple I find it a little hard to explain clearly how to blend textures together so I drew a crude diagram below to illustrate the point.

First the base color for the tubes that connect to the heart and the main body of the heart are made to be the same.

Next, working on the heart texture in the texture editor, the color image is applied to the heart using UV mapping. Then the mask image is applied as a layer on top of the color layer and the blending mode of the mask is set to "Alpha". Wherever there is black in the mask, the color layer below will be masked, allowing the base color of the object to show through. Since I have made the base color of the heart the same as the color of the large arteries and veins that attach to it, the arteries and veins appear to blend smoothly into the heart texture

STEP 7
I was not happy with the flaps on the heart that covered the left and right atriums. I cut these parts of the model away and recreated them. I textured these separately with image maps below.

UV map:

Bump map:

Color map:

The finished heart: