Hamish wrote: > > For a long time it has been unclear to me, do kernels live in the > middle of each face like an area centroid with 3D coordinates, or is it > for true 3D topology like a single point somewhere within a closed > volume defined by many faces. > > ie would a cube get a single kernel in the center of it* or six > kernels, one on each face?
That's exactly what I'd like to know too! My recent updates to v.hull for generating 3D hulls from 3D points threw this one up. I have decided to put one single kernel into the center of gravity for the hull, as it seemed to me that this is the 3D equivalent to a 2D boundary with one centroid. However, if anyone here sees a need for adding kernels to all faces, that would be a trivial thing I could add to v.hull (perhaps with a flag to turn them on?). > > [*] if kernel-as-center-of-volume that could hold attribute info like > building address or geological mineral type. For kernel-on-face I can't > think of what kind of attribute you would want to attach to a wall > besides something obvious like "north facing". > > Thus I'm leaning to the kernel-as-center-of-volume meaning. > > In that case a TIN describing a DEM might just get a single kernel, in > the middle of XY space and placed below the surface to describe the > interior side. (?) > > But it would probably only be meaningful for a closed TIN "sphere" of > the entire geoid surface. > > > ??, Yes, this question would definitely be interesting to discuss for the v.delaunay 3D update, too. Benjamin -- Benjamin Ducke, M.A. Archäoinformatik (Archaeoinformation Science) Institut für Ur- und Frühgeschichte (Inst. of Prehistoric and Historic Archaeology) Christian-Albrechts-Universität zu Kiel Johanna-Mestorf-Straße 2-6 D 24098 Kiel Germany Tel.: ++49 (0)431 880-3378 / -3379 Fax : ++49 (0)431 880-7300 www.uni-kiel.de/ufg _______________________________________________ grass-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-dev
