Creating a texture template with minimized distortion

Author: CHWT

Tools Needed

* Any 3D application that can export models in OBJ format (or file conversion utilities to convert your model into OBJ format)

* UV Mapper Classic

* Wings3D

* A 2D graphics application for texturing

Suppose that you have created a 3D model. Now also suppose that you are on a budget and you only have the free UV Mapper Classic that can be downloaded at www.uvmapper.com. You can create a texture template using UV Mapper Classic, but sometimes you might not be happy with the result of the mapping. In many occasions the texture maps created by UV Mapper Classic have the vertices so close together that, when the model is being textured, distortions might be found in the render. In this tutorial I will show you how to create a texture template with minimized distortion with the help of Wings3D, which is also available as a free download at www.wings3D.com.

I have created a pants model for Michael 3 using a Japanese (but can be chosen to run in an English interface) free 3D application Metasequoia LE which can be downloaded at www.metaseq.net. I exported the model in .lwo format and later converted it into OBJ format with some file conversion utilities.

Now open UV Mapper Classic. Click “File”, then click “Load Model” to load my model, in this case “michael3pants.obj”.

If a dialogue box pops up to ask you to correct any out of range UV coordinate data, click “Yes”.

I first apply a planar mapping to the model by clicking “Edit”, then “New UV Map”, then “Planar”, and choosing “Split By Orientation” in the dialogue box.

I really don't like planar mapping as the vertices on the sides of my model are so close together or even hidden, making it difficult to texture my model.

So I try the cylindrical mapping on my model by clicking “Edit”, then “New UV Map”, and then “Cylindrical”.

This time some faces of the thighs and legs overlap, again making it difficult to texture my model.

So now I try to map both my left and right halves of my model cylindrically. And the result is much better. No faces overlapped.

I will first export the model to “michael3pants_uvmapper_corrected.obj” by clicking “File”, then “Save Model”, and choosing “OK” in the dialogue box.

Export the texture template to “michael3pants_uvmapper_correctedBMP” by clicking “File”, then “Save Texture Map”, and choosing the bitmap size to be 2048 by 2048.

However, you can see the vertices at the crotch area are extremely close. You can actually see that when I render “michael3pants_uvmapper_corrected.obj” in Metasequoia LE with “michael3pants_uvmapper_correctedBMP” as the texture map, the texture at the crotch area is messed up.

So now we call Wings3D for help.

First import “michael3pants_uvmapper_corrected.obj” into Wings3D.

Then click the fourth pyramid that is bound by the small white square and pointed by the red arrow in the following picture.

Then click “Ctrl+A” to select all the faces. The selected faces will be highlighted in red.

Then click “Window”, then “UV Editor Window” to activate the UV editor window.

In the UV editor window, right click, then select “ReMap UV”, then “Stretch Optimization”.

When Wings3D has finished stretch optimization, press the space bar to deselect all the faces. You can see the UV of the model has changed slightly, especially around the crotch area. The vertices there are no longer so close. This will facilitate the texturing of the model.

Export the model as “michael3pants_wings3D_corrected.obj”.

Click “File”, then “Load Model” to import “michael3pants_wings3D_corrected.obj” into UV Mapper Classic.

Export the texture template to “michael3pants_wings3D_correctedBMP” by clicking “File”, then “Save Texture Map”, and choosing the bitmap size to be 2048 by 2048.

Now you can import “michael3pants_wings3D_corrected.obj” into a 2D graphics application to start texturing the pants for Michael 3.

To show how the UV has become better for texturing, the following is a test render of “michael3pants_wings3D_corrected.obj” in Metasequoia LE using “michael3pants_wings3D_correctedBMP” as the texture map. No more mess at the crotch area.

Although we can directly use the “Unfold” function of Wings3D to unfold (i.e., to map) our models, the result may be undesirable such that the model is broken up along weird seams or the resulted mapping is messed up. It is better to use UV Mapper Classic to first obtain a draft UV map, and then use Wings3D's stretch optimization function in the UV editor window to fine-tune the mapping.

Happy modeling and texturing!