Hi, vtk that is used by loch has a volume calculation filter. I created Tools->Survey statistics dialog in the latest commit, where volume for LRUD envelope and scrap walls is calculated separately.
Hopefully, it will give some reasonable numbers. There is still a problem, that if there is 3D data interpolated from splay shots - they self intersect a lot. They are exported as scraps, so with these data, it will probably give unrealistic large numbers. S. On Sun, 30 Jan 2022 at 00:43, Tarquin Wilton-Jones via Therion < [email protected]> wrote: > > In this case the cave is very small, only 50 meters, and there are only > 14 survey stations. Retyping it into a Compass data file did not take long. > > > > Compass and MeshLab do very different calculations to come up with > volume. For my cave Compass gives about 2900 cubic feet and MeshLab gives > over 20,000 cubic feet (about 585 cubic meters). Compass is doing a simple > calculation based on polygons and using only centerline plus LRUD. MeshLab > is a much more complex calculation based on a 3D model of triangles. > Ultimately its calculation can be traces back to centerline, LRUD, walls, > passage height objects and cross sections. Therion uses all of that to > build a .lox file which, through translations, becomes the MeshLab file. > > If it's that short, I would be tempted to do it manually, for a kind of > sanity check. Pretend it's a cave made up from cuboids. Take the cross > sectional area for each station (passage height * width), calculate the > cuboid volume for each leg. See if it closer to one of the other. > > The MeshLab version seems like it might be doubling (or more) up, > because of the way Therion generates cave tubes and passages from > multiple overlapping 3D shapes, not a single "tube". One tube for the > leg, then extra 3D shapes layered into the same 3D space for the wall > drawings. If MeshLab is treating those as separate entities, rather than > just the overall outer volume, then it will get a vastly larger > measurement. > _______________________________________________ > Therion mailing list > [email protected] > https://mailman.speleo.sk/listinfo/therion >
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