Transcript SIF end-of-project summary

CHS
UCB
CyberCut Retreat, Jan. 2000
SIF -- End of Project Review
Carlo H. Séquin
CHS
What We Have Learned
UCB
Interchange format == design language !
Difference between SIF and SLIDE !
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Key issues in design language:
ease of use, high-level expressibility.
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Key issues in interchange format:
simplicity, robustness, nonambiguity,
“cleanliness” (SFF: water-tight surfaces).
CHS
UCB
SIF_SFF 1.0 ===> SIF_SFF 2.0
How SIF differs from our initial design:
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Shells are connected, water-tight surfaces:
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All vertices must be completely shared
by a disk of surrounding triangles.
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No complicated (possibly non-planar) faces.
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No curved patches (triangle meshes only).
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No instantiations of shell fragments
(avoid cracks due to rounding errors).
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No triangle strips, fans, arrays.
Floating point numbers are OK:
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Receiving end works in FP anyway (unlike EDIF).
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The SIF (exp …)-construct was heavily misused.
CHS
UCB
SIF_SFF 1.0 ===> SIF_SFF 2.0 (cont.)
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Topology follows from geometry:
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Each shell gets topology from explicit edge connectivity.
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Boolean operations between closed (positive) shells
allow to specify parts with voids,
and make it easy to design overlapping constellations.
No referencing by names:
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Only vertices are referenced for reuse
by array indices within the local scope of their shell.
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No reuse of shared surfaces by adjacent lumps
(the exact same vertex coordinates should be
specified again for the surface of the other lump).