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This tutorial is made to explain step-by-step all the stages I'm passing by to map a car. In this example, I'm mapping the engine of the my little Renault Spider. To achieve that, I'm using a 3D half-sphere to help me to go quicker. This little 3D object need to be merge in the scene with its current size.


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To make things clearer, I create a multi/sub-object material with 2 materials #1 and #2. The #1 material is pink and I assign all non yet mapped faces with this one. The #2 material is the final material to be used. For mapping the whole engine and the chassis, I choose to use a texture of 1024x512.


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First thing : simply select the 6 face at the top of the engine.


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Assign the #2 material to the selection


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Apply an [UVW Map] modifier. then press the [Acquire] button.


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Those faces are oriented like the top of the half-sphere (zMg=To:100 Le:0 Fr:0 part). So, selecting the top of the sphere will copy the mapping o this part to the current selection. Then, select the "[Acquire Absolute] choice.


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Click on the [Center] button.


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The current size of the mapping gizmo is 3.5m x 7.0m. This size has been established for a 2048x1024 texture. In our case, we have to replace those values by 1.75m x 3.5m.


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Add an [UVW Unwrap] modifier. Click on the [Edit] button. Move the wireframe where you want.


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Collapse the whole stack of modifiers.


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Just a little remind about my magnet settings.


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With TExporter (see this tutorial), you can create the first version of the wireframe. Save it on the default texture used by #2 material.


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The mapping continues : select the 6 faces at the rear of the engine. Assign #2 material.


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Like above, assign an [UVW Map] modifier and acquire the best part to match with the faces orientation. Here, it's the rear zMg=To:0 Ri:0 Re:100 part which match perfectly. Center the mapping and put the correct dimensions (1.75 x 3.5).


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Add a new modifier [UVW Unwrap] and move the wireframe where you want. Take care to not overlap the previous wireframe of course. Things can be aligned correctly using the snapping capabilities of 3DSMax.


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Collapse the stack. Select all faces with #2 material.


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One new [UVW Unwrap] to stick perfectly both parts together.


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TExporter again.


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One sample mapping result. Every mapping is different so it's just a solution.


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Now, a more difficult case : when faces are oriented with an axis not present on the half-sphere. It's quite simple : just select the symetrical part of the half-sphere (here : zMg=To:25 Le:0 Re:75). Then, in the [UVW Unwrap] tool, just do a symetry.


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Here is a possible result for the whole engine. Note the little trick with blue and red points to check everything is good.