On Thursday, 11 July 2019 16.28.43 EDT James R. Frysinger wrote: > Pierre, it took me a bit to figure out what you were talking about. I > take it now that a point cloud is a cluster of points and that TIN > refers to a triangulated irregular network, used by ArcGIS. Are those > guesses correct?
Yes, except this isn't ArcGIS. The TIN will be used to check the accuracy of the point cloud by comparing GPS elevations of sample points with what the TIN says they are. > As for the pull-down menu I suggest that you use the same unit for all > the choices, at least within that foot/meter framework. That is, if the > user opts to work in feet, use feet. If the user opts to use meters, use > meters. Definitely do no flip back and forth within one menu between > those two units! What if the user selects that the input file is in feet and the output file is in meters? Then there are three different feet (international, US survey, and Indian survey). > At some point you will have to deal with conversion round-offs. I would > go with picking my favorite unit for the tolerances and making a note in > the other framework that some round-offs occurred and why. > > If working with tolerances in meters, I suggest choosing a reasonable > variety of choices, such as 2 dm, 4 dm, 6 dm, etc. They are 10 mm, 25 mm, 50 mm, 100 mm, 150 mm, 200 mm, 1/3 m, 2/3 m, 1 m, and 10/3 m. That's what the standard says, except it rounds them off. How they picked those numbers is beyond me. If I were choosing the tolerances, I'd choose some approximately logarithmic set, such as the E series or the Renard series. Pierre -- La sal en el mar es más que en la sangre. Le sel dans la mer est plus que dans le sang. _______________________________________________ USMA mailing list [email protected] https://lists.colostate.edu/cgi-bin/mailman/listinfo/usma
