OCONV(1)						      General Commands Manual							  OCONV(1)

NAME

       oconv - create an octree from a RADIANCE scene description

SYNOPSIS

       oconv [ -i octree | -b xmin ymin zmin size ][ -n objlim ][ -r maxres ][ -f ][ -w ][ - ] [ input ..  ]

DESCRIPTION

       Oconv  adds each scene description input to octree and sends the result to the standard output.	Each input can be either a file name, or a
       command (enclosed in quotes and preceded by a `!').  Similarly, the octree input may be given as a command preceded by a `!'.   If  any	of
       the surfaces will not fit in octree, an error message is printed and the program aborts.  If no octree is given, a new one is created large
       enough for all of the surfaces.

       The -b option allows the user to give a bounding cube for the scene, starting at xmin ymin zmin and having a side length size.  If the cube
       does not contain all of the surfaces, an error results.	The -b and -i options are mutually exclusive.

       The  -n	option specifies the maximum surface set size for each voxel.  Larger numbers result in quicker octree generation, but potentially
       slower rendering.  Smaller values may or may not produce faster renderings, since the default number (6)  is  close  to	optimal  for  most
       scenes.

       The  -r	option	specifies  the	maximum  octree resolution.  This should be greater than or equal to the ratio of the largest and smallest
       dimensions in the scene (ie. surface size or distance between surfaces).  The default is 16384.

       The -f option produces a frozen octree containing all the scene information.  Normally, only a reference to the scene files  is	stored	in
       the octree, and changes to those files may invalidate the result.  The freeze option is useful when the octree file's integrity and loading
       speed is more important than its size, or when the octree is to be relocated to another directory, and is especially  useful  for  creating
       library objects for the "instance" primitive type.  If the input octree is frozen, the output will be also.

       The -w option suppresses warnings.

       A hyphen by itself ('-') tells oconv to read scene data from its standard input.  This also implies the -f option.

       The  only  scene file changes that do not require octree regeneration are modifications to non-surface parameters.  If the coordinates of a
       surface are changed, or any primitives are added or deleted, oconv must be run again.  Programs will abort with a "stale octree" message if
       they detect any dangerous inconsistencies between the octree and the input files.

       Although  the  octree  file format is binary, it is meant to be portable between machines.  The only limitation is that machines with radi-
       cally different integer sizes will not work together.  For the best results, the -f option should be used if an octree is  to  be  used	in
       different environments.

DIAGNOSTICS

       There are four basic error types reported by oconv:

	      warning - a non-fatal input-related error

	      fatal - an unrecoverable input-related error

	      system - a system-related error

	      internal - a fatal error related to program limitations

	      consistency - a program-caused error

       Most errors are self-explanatory.  However, the following internal errors should be mentioned:

       Too many scene files
	      Reduce the number of scene files by combining them or using calls to xform(1) within files to create a hierarchy.

       Set overflow in addobject (id)
	      This  error  occurs  when  too many surfaces are close together in a scene.  Either too many surfaces are lying right on top of each
	      other, or the bounding cube is inflated from an oversized object or an improper -b specification.  If  hundreds  of  triangles  come
	      together	at  a  common  vertex, it may not be possible to create an octree from the object.  This happens most often when inane CAD
	      systems create spheres using a polar tessellation.  Chances are, the surface "id" is near one of those causing the problem.

       Hash table overflow in fullnode
	      This error is caused by too many surfaces.  If it is possible to create an octree for the scene at all, it will have to be  done	in
	      stages using the -i option.

EXAMPLE

       To add book1, book2 and a transformed book3 to the octree ``scene.oct'':

	 oconv -i scene.oct book1 book2 '!xform -rz 30 book3' > newscene.oct

AUTHOR

       Greg Ward

NOTES

       In  the	octree, the names of the scene files are stored rather than the scene information.  This means that a new octree must be generated
       whenever the scene files are changed or moved.  Also, an octree that has been moved to a new directory will not be able to find scene files
       with  relative  pathnames.  The freeze option avoids these problems.  make(1) or rad(1) can be used to automate octree creation and mainte-
       nance.

SEE ALSO

       getbbox(1), getinfo(1), make(1), obj2mesh(1), rad(1), rpict(1), rvu(1), rtrace(1), xform(1)

RADIANCE
							      8/15/95								  OCONV(1)