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?
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!
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.
Jim
On 7/11/2019 14:10, Pierre Abbat wrote:
I'm writing a program that takes a point cloud and produces a TIN within a
specified tolerance. A few days ago I met with a fellow surveyor named Pat,
who gave me a document specifying vertical accuracy classes, ranging from 1 cm
to 333.3 cm. I'm sure that this last number is actually 10/3 m, and likewise
for 2/3 and 1/3. (Another number is given as 1.414 in one place and 1.4142 in
another, but it's obvious that the exact value is √2.) I have to put a GUI on
the program, with a pulldown or something for selecting the tolerance.
1. Should I always display the tolerance in meters or millimeters, or should I
display it in feet if the file is in feet (which will be another option)?
2. If it's always in meters, how should I display 10/3 m? (If it's displayed
in the file unit, it'll be displayed with 7 sig figs, to be different
depending on which foot is selected.)
Point densities are quoted in dots per square meter, even when the point cloud
file is in feet.
Pierre
_______________________________________________
USMA mailing list
[email protected]
https://lists.colostate.edu/cgi-bin/mailman/listinfo/usma
