Specify method for the UV parametrization
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Projection - In this case for the UV parametrization of each facet the coordinates are projected on a certain plane
Use current UV data - In this case it is used the texture coordinates which are already set. This method can be useful for the models which come from other programs, where the texture coordinates were set (on the picture below it is possible to see the example for the model from SketchUP).
LSCM (Triangles) - Least Squares Conformal Maps is a more complex algorithm, which allows us to receive better unwrapping results. There is one important restriction for the current implementation of this algorithm, namely all facets must be triangles.
Current main unwrapping algorithm (Projection) for the TC Surface case is very simple and thus gives bad results for the many cases. For example, for the segment shown on figure 1, we will receive bad segmentation, which is shown on the figure 2. Here it is important to note, that segment from figure 1 has facets on the side part of the shoes, which are orthogonal to the facets from the base part of the shoes. That is why in this case Projection algorithm gives us bad results.
Figure 1. Segment which has practically orthogonal facets to each other.
Figure 2. Unwrapping results for the segment from fig. 1 by using Projection algorithm.
This was a motivation to add some additional more complex algorithm, which allows us to receive better unwrapping results. For this purpose we choose Least Squares Conformal Maps (LSCM) algorithm. But there is one important restriction of the current implementation of this algorithm – all facets should be triangles. But it is not very strong restriction, because practically all surfaces, which is come from the side applications has exactly triangle facets.
If user wants to use LSCM algorithm, he can do it via common UV Mapping Options dialog (see Fig.3.).
Figure 3. UV Mapping Options dialog (choosing LSCM).
At it is possible to see from the fig. 4, LSCM gives much better results (in comparison with projection, see fig. 2) for tested example.
Figure 4. Unwrapping results for the segment from fig. 1 by using LSCM algorithm.
Specify the projection direction for UV parametrization
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Note: This option is valid only for the Projection method.
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Z-axis - In this case as a projection direction the Z – axis of the current workplane is used.
Specify the parameters direction for UV parametrization
Fix self-intersections in 2D parts - This option affects the presence of self-intersecting facets in 2D parts. This can lead to artifacts in rendering. When this option is enabled, during unwrapping presence of self-intersections is checked, and an attempt of resegmentation is made with the purpose to remove self-intersections. This procedure may take a few iterations and considerable time but it is recommended for the complex bodies.
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