Peter Clifton wrote: > stl (very nice)
IMHO, stl is a mesh only format. That is, everything is made of triangles -- no squares, no circles, no real curvatures. There are no macros, no loops, or repetitions. A decent pcb would make for a pretty large stl file if all the vias and pin holes were to be modeled realistically. Named objects are unknown to stl. This renders stl a one way format for most construction purposes. Vital information like the diameter of holes or boolean operations of solids cannot be included. In original stl there is no way to give color or texture information. There are color extensions, though. Their color depth is confined to 15 bit. So shades tend to look like a zebra. Most of the above is true for vrml, too. Due to its ability to associate textures with surfaces, it may be the format of choice for good looking pictures. For construction purpose, it is a dead, though. > iges (simple format, but I have no clue what the syntax is ;)) syntax description is supposed to be available here: http://www.uspro.org/documents/IGES5-3_forDownload.pdf/view My browser is unable to connect, though. This format is more CAD friendly in that it allows for cylindrical, spherical and even spline defined surfaces. In addition, it knows about objects. Because of this, iges can capture the exact dimensions of engineered parts. For most CAD applications there is still loss of information on export. Surfaces are contained as is, not as rendered by construction points. Color is added by object. There is no way to attach textures to surfaces. So unfortunately, iges does not lend itself to efficient production of eye candy > STEP (_utterly_ evil format). This standard is supposed to cover every aspect in production of every industrial product, dismantling and recycling included. Even with thousands of pages, it can only scratch on the breadth of this goal. Most CAD vendors seem to have gravitated to the automotive subsection. In addition, step exports seem to limit itself to about the rage of features that iges can provide. That is, a geometrical description of the surface. The specification of the format is kept almost as a secret. I wasn't able to get a glimpse on it for free. For 3D features in pcb, all of the above suffer from some kind of deficiency. ---<)kaimartin(>--- -- Kai-Martin Knaak Öffentlicher PGP-Schlüssel: http://pgp.mit.edu:11371/pks/lookup?op=get&search=0x6C0B9F53 _______________________________________________ geda-user mailing list [email protected] http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
