Hi Sean, I'm back with questions - I'm still not clear how the surface/volume of hollow objects should be interpreted.
I created a simple setup to clear that: in sphout.s sph 0 0 0 2 in sphin.s sph 0 0 0 1 c -r sph_hollow.r (sphout.s - sphin.s) B sph_hollow.r This is basically a hollow sphere, which is very similar as topology to what you can possibly get with some pipe objects. The surface/volume this object should have will in any case answer my questions. Now "analyze sph_hollow.r" gives me: analyze: unable to process ID_COMBINATION solid This is not very helpful... For volume, I see 2 interpretations: * only calculate volume which is materially taken by the object (so that volume*density=weight); * calculate the "boundary volume" -> imagine submerging the object completely in water, and calculate the volume of water it would displace; Both can be of interest for different applications. For surface it's about the same - a total surface counting interior surfaces too, and a boundary surface which would be the contact surface with a liquid when completely submerged. I guess this "outside"/"inside" surface can be generalized to a surface reachable from a given point in space - then the outside surface is whatever is reachable from a point outside the bounding box, inside surfaces can be actually many depending how the object is built (can have many non-communicating holes). >From an algorithm POV I would prefer the "material volume" and "total surface" approach - they are the easiest to calculate. But the "boundary volume" and "reachable surface" could be valuable functions too ! I'm not sure if this is documented somewhere already, if so, please point me to it... otherwise, please let me know what's BRLCAD's approach to this. Cheers, Csaba ------------------------------------------------------------------------------ Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis & visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter _______________________________________________ BRL-CAD Developer mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/brlcad-devel
