If your system comes without 3D graphics hardware or library, use the Mesa library. Mesa is a very fine free graphics library with OpenGL-like interface. See www.mesa3d.org for more information.
If you do not have Motif, the free Motif clone library lesstif works fine. See www.lesstif.org.
If you want TIFF support, you need Sam Lefflers TIFF library (libtiff) which can be obtained from SGI's ftp site or mirror sites. You need version 3.4beta037 (september 1997) or more recent for high dynamic range (LogLuv) format support (thanks Greg W. Larson!). If you have an older libtiff, it still can be used for writing LZW-compressed display-RGB images. TIFF support can be disabled as well if you don't want it.
In order to be able to read XRML input
files, you need XRML,
the eXtensible vRML based scene graph library by Philippe Bekaert and
collaborators. XRML support can be disabled if you don't want it.