Texturing complex models in GMAX
I was struggling with this issue for a long time and with this contribution I hope I can help some people getting started with it. My example refers to aircraft development although I am sure you can apply it to many other disciplines as well. The methodology described in the first paragraph is what I find very handy. Please feel free to add your experiences and methods as well!
Step one: Unwrapping the model in GMax
We start with a finished part of the model. It is assumed that you already set up a proper Material and applied it to the model. Shown as an example is the nose section of a Lockheed L-10A Electra in its final stage.
Please note that you cannot make any major changes on the mesh (adding/removing/welding vertices for instance) without doing the UVW mapping again! Knowing that, you add a "Mesh Select" modifier to your stack.
Select "Polygon" and make sure that the option "Ignore Backfaces" is checked - that makes the selection easier. Select the parts of the aircraft you want to texture first. I started by selecting the whole left side and then removing the polygones facing to the top and bottom.
Add a "UVW Map" Modifier to your stack. Make sure it is situated on top of the "Mesh Select" modifier.
In the modifier options, make sure that the UVW Map Modifier is of a planar type and make the length/width parameters equal the size, on the other hand, doesn't really matter, because we will scale the uvw map anyway.
Addendum: Clicking "Fit" from the lower set of buttons automatically adapts the langth and width parameters of the plane to the selected polygons.
Add an "Unwrap UVW Modifier" to your modifier stack. Once again: make sure its on top of the list!
By clicking the "Edit" button, the "Edit UVWs" window will appear.
If you've applied a Material/texture you used for other parts of the model before, or if you had a rough idea how to section it for the different parts, you can set it as background by clicking on "Pick Texture" (not further explained here).
Select the whole map, scale it down, and move it to the place where you want to have it for easy painting. Remember where you put it!
Close the Window and repeat the last steps again, starting with the "Mesh Select" modifier.
You can repeat it as often as you want - the more complex your model is, the more often you will repeat them.
You can see one example where this method is quite useful below:
You can adjust the Gizmo of the "UVW Mapping" Modifier as you need it for a certain selection, without dealing with the other selections of the model. You can for instance consider using a cylindrical Modifier for the Nose and a box for the rest of the model. It's up to you!
Step two: Creating the basic texture
Open your graphic program - in this case I use Photoshop, but it will work with any other convenient program as well. Create a new file with the size you want. Change to GMAX and go back in the modifier stack to the first "Unwrap UVW" modifier. Click on "Edit" again.
Maximize the window and zoom out so that you can see the dark grey border line of the texture. Hit the "Print" button to copy what you see to the clipboard. Open Photoshop again and press "Ctrl+V" (for all the German readers: "Strg+V" Besten Gruss! :D). The result will be something like this:
Select everything within the dark grey border, then inverse the selection and delete everything else by hitting the "Delete" button. Select all (Ctrl+A) and scale the image up until it fills the whole canvas.
Choose the magic wand, deselect "continuous", click on the grey area and press "delete" on the keyboard. As a result you will have the extracted mesh and can use this layer for instance as a semi transparent helper for editing your texture.
Repeat these steps for every selection of the part and arrange them in photoshop until you are satisfied.
After all that is done save the texture with the Mesh layers activated. Change to GMAX again and reload the diffuse map of your material. Beginning with the first "Unwrap UVW" modifier fine tune the placement of the uvw map to match up the selection with the mesh layers of the texture.
Thats all! Now you have a good basis for creating your paintwork.
I presented my methodology of texturing a complex model. The beauty of the method presented here is that you can adjust the "UVW Mapping Modifier" for each selection. This becomes handy for parts situated in weird angles like the front windows as shown above.