Tutorial for LSCM UVs (Unwrap 3D Pro)

Simply speaking, LSCM UVs (Least Squares Conformal Maps) is a tool to help minimize texture distortion without introducing a lot of seams. Seams are edges along where UVs are discontinuous.

In Ultimate Unwrap 3D, the LSCM UVs tool relies on how your 3D model is connected, so it is best to weld your model's faces before proceeding.


LSCM Example

For this example, we will use the face of Beethoven to demonstrate LSCM UVs:

tut_lscm1a.png

tut_lscm1b.png

In Ultimate Unwrap 3D, the highlighted green edges show where boundary edges are located on the model.

Note that for this specific example, it is not necessary to mark edges for unwrapping, as our seam is already defined by the model's boundary edges.


Now, click Ctrl+A to select all faces, then click 2D Tools | LSCM UVs:

tut_lscm2.png

As you can see, the model is now unwrapped, however, the UV mapping is not perfectly symmetrical. We can solve this problem by locking UVs. When a UV is locked, its position will not move when LSCM UVs is applied.


Locking UVs

However, what UVs should we lock? Before going further, let's first explain how the LSCM tool works behind the scenes. When no UVs are locked, LSCM will project your model's vertices to a mapping plane by default. Then, it will lock two vertices: the maximum and minimum. So, to get similar results, we should lock at least two UVs, ideally at opposite poles. And then let the magic of LSCM fill in the missing pieces.

tut_lscm3.png

As shown above, we will lock the top and bottom UVs that are located along the centerline of Beethoven's face. In vertex selection mode, click Edit | Lock | Selected UVs. To insure that the two UVs are aligned vertically, click Edit | Straighten | Vertical to straighten them out.


Now, in face selection mode, click Ctrl+A to select all faces, then click 2D Tools | LSCM UVs again:

tut_lscm4.png

Now, our UV mapping is symmetrical along the centerline of Beethoven's face.


Finally, if we assign a material with a checker texture map to all faces, we can see that there is minimal texture distortion, which is good enough for most purposes:

tut_lscm5.png


Summary

We learned how to use the LSCM UVs tool to minimize texture distortion and how to modify the UV mapping by locking UVs. In short, the LSCM UVs tool allows users to create new UVs, or use pre-existing UVs when locked.

That's it! If you have any other questions about LSCM UVs, please let us know.
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