IV is the format used by the Inventor modeling/rendering package from SGI.
irit2iv [-l] [-4] [-P] [-F PolyOpti FineNess] [-f PolyOpti SampPerCrv]
[-T] [-z] DFiles
-l: Linear - forces linear (degree two) surfaces to be approximated by a single polygon along their linear direction. Although, most of the time, linear direction can be exactly represented using a single polygon, even a bilinear surface can have a free form shape (saddle like) that is not representable using a single polygon. Note that although this option will better emulate the surface shape, it will create unnecessary polygons in cases where one is enough. -4: Four - Generates four polygons per flat patch. Default is 2. -P: Polygonize freeform shapes. Default is to leave freeform curves and surfaces as is. -F PolyOpti FineNess: Optimality of polygonal approximation of surfaces. See the variable POLY_APPROX_OPT for the meaning of FineNess. See also -4. -f PolyOpti SampPerCrv: Controls the method used to approximate curves into polylines. If PolyOpti == 0, equally spaced intervals are used. Otherwise, an adaptive subdivision that optimizes the samples is employed. -T: Talkative mode. Prints processing information. -z: Prints version number and current defaults.
Irit2Iv converts freeform surfaces and polygons into polygons and saved in iv Inventor's ascii file format.
Example:
irit2iv solid1.dat > solid1.iv
Surfaces are converted to polygons with fineness control:
irit2iv -F 0 16 - view.mat < saddle.dat > saddle.iv
Note the use of '-' for stdin.