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