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.\" RCSid "$Id"
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.TH OBJ2MESH 1 03/11/03 RADIANCE
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.SH NAME
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obj2mesh - create a compiled RADIANCE mesh file from Wavefront .OBJ input
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.SH SYNOPSIS
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.B obj2mesh
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[
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.B "\-n objlim"
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][
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.B "\-r maxres"
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][
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.B \-w
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]
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[
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.B "input.obj"
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[
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.B "output.rtm"
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]
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]
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.SH DESCRIPTION
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.I Obj2mesh
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reads a Wavefront .OBJ file from
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.I input.obj
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(or the standard input) and compiles it into a RADIANCE triangle mesh,
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which is sent to
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.I output.rtm
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(or standard output).
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This mesh may be included in a RADIANCE scene description via the
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.I mesh
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primitive, thus:
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.IP "" .2i
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mod mesh id
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.br
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1+ output.rtm [xform args]
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.br
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0
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.br
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0
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.PP
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The syntax and semantics are nearly identical to the RADIANCE
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.I instance
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primitive, except that the mesh modifier may not be "void", since
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materials are not included in a compiled mesh file.
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.PP
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The
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.I \-n
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option specifies the maximum surface set size for
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each voxel.
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Larger numbers result in quicker mesh generation needing
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less memory, but potentially slower rendering.
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Smaller values may produce faster renderings,
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since the default number (15) is on the high side to reduce
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the compiled mesh octree size.
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Values below 6 are not recommended, since the median
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valence (number of adjacent faces) for a mesh vertex is 6,
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and smaller limits will result in pointless octree subdivision.
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.PP
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The
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.I \-r
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option specifies the maximum octree resolution.
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This should be greater than or equal to the ratio of the mesh bounding
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box to the smallest triangle.
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The default is 16384.
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.PP
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The
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.I \-w
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option suppresses warnings.
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.PP
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Although the mesh file format is binary, it is meant to be portable
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between machines.
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The only limitation is that machines with radically different integer
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sizes will not work together.
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.SH DIAGNOSTICS
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There are four basic error types reported by obj2mesh:
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.IP
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warning - a non-fatal input-related error
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.IP
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fatal - an unrecoverable input-related error
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.IP
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system - a system-related error
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.IP
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internal - a fatal error related to program limitations
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.IP
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consistency - a program-caused error
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.PP
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Most errors are self-explanatory.
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However, the following internal errors should be mentioned:
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.IP "Set overflow in addobject (id)"
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This error occurs when too many surfaces are close together in a
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scene.
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Sometimes a dense mesh can be accomodated by increasing
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the maximum resolution (by powers of two) using the
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.I \-r
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option, but usually this error indicates something is wrong.
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Either too many surfaces are lying right on top of each other,
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or the bounding cube is inflated from disparate geometry
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in the input.
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Chances are, the face number "id" is near
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those causing the problem.
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.IP "Hash table overflow in fullnode"
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This error is caused by too many surfaces, and there is
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little hope of compiling this mesh.
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.SH EXAMPLE
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To create a compiled triangle mesh from the scene file mesh.obj:
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.IP "" .2i
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oconv mesh.obj mesh.rtm
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.SH AUTHOR
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Greg Ward
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.SH "SEE ALSO"
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gensurf(1), getinfo(1), make(1),
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oconv(1), rpict(1), rview(1), rtrace(1), xform(1)
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