1. Star Upper ratio calculation on start facet example highlighted with pink:
All calculation are performed in 2D. Model is projected on table facet plane
1.1 Draw a line a through start facet edge belongs to table. Line will separate plane into surfaces β and δ.
1.2 Find most distant point (call it B) on start facet from line a. A is point, where perpendicular from point B is crossing line a:
1.3 Find most distant point on girdle (call it D) from line a, pint should belong to β surface. C is point, where perpendicular from point D is crossing line a:
1.4 Start Upper ratio is |AB| length divided by |CD| length.
In projection on Table plane, for each Star facet:
- Find the most distant point belong to the Star facet from line between Star and Table facets. Call it "A".
- Find the most distant point from this line on the girdle (in the same half-plane). Call it "B"
- StarUpperRatio is A/B.
This most consistent case for this algorithm is "F:E" shown on picture above. Please pay attention that segments measured above do not belong to the same line in all cases.