Hello,
Very new to Rhino. I’m attempting to model topography in Rhino using contour lines from ArcGIS with 10ft intervals, but when I import the dwg file, the contours are stuck in a vertical plane. I imagine it has something to do with my import settings but I’m not sure what to change. Any help would be much appreciated
Hi Elijah,
you can use _setPt to project the cuves on the cplane (you can also use the command _Project with a planar surface, take a look at the Rhino help for the command’s options).
It’s not the import settings, it’s most likely the export settings from ArcGIS. The heights are correct in meters or feet, but the XY coordinates were probably exported as seconds of arc and not meters or feet. Seconds of arc values are very small, which is why the curves are tiny in X and Y.
If you can share the DWG we can take a look and help you out easier.
Sure! Here it is:
contour_ExportCAD1.dwg (1.1 MB)
That makes sense, I’ll look into changing the cords for the x,y. Having trouble finding the settings for that in Arc; if you could point me in the right direction that would be amazing. Thanks!
I have no experience with ArcGIS, we used to use QGis but it was always an incredibly complicated, clunky interface. The trick is setting up the correct output projection, but I don’t remember how, been too long.
I wrote an ASCII Grid importer for Rhino because at the time we were getting a lot of those. These days it’s more .xyz which import directly. But at the time many of the data download sites were supplying files in arc seconds. Below is the comment in my file:
MULTIPLIER because cellsize could be in degrees, not meters!
1 degree earth's circumference at equator is about 111.319 km (111319) m;
Pole to pole it's only about 111.133 m. Basis for nautical mile (1 arc minute)
is 1,852 m or a multiplier of 111120 m.
Try to autodetect this condition: if cell size is less than 0.02
then likely the cell size is degrees...
3 arc seconds will show a value of .000833333 as a cell size
1 arc second will have a value of .000277777 as a cell size
However - result may still not be correct -
as arc second files are ##spherical projections##.
Awesome! Figured it out in Arc! Just needed to project the contour’s source data cords to state plane (something in feet rather than arc degrees like you said) and export that to Rhino. Thanks for your help.
Good that you figured it out.
And if you need a simple tool to generate a mesh from the curves you can test out TerrainMesh that you can find on the pluginmanager.
Here I moved the curves close to origin so the mesh is displayed properly. Rhino doesn’t like having objects too far from the origin due to floating point numbers.
