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Profile Graphs and Elevations as CSVs

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#1
Archmap

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I need to generate a series of CSV files marking off elevations from a DEM along 60 or so straight survey lines.

I have tried both the quick and dirty interpolate line tool on the 3D Analyst tool bar as well as the Interpolate Shape tool to add Z values to my polyline shapefiles. Neither works they way I need it too.

What seems to be a large part of the problem is that my DEM has a good number of gaps in it anywhere from 1 pixel (3m) to 100 pixels (300m). Since this is a large survey area and these are long survey lines, interpolating across the gaps is fine for my purposes. But ArcGIS doesn't like it. I can coax usable data out of the quick and dirty interpolate to line tool, but the issue is that I need to reproduce the exact same lines for DEMs of the same area made from different years. Drawing the lines by hand is fine for one DEM, but when I need to redraw that line in the exact same place for each of my DEMs it gets tricky (there are also a lot of lines).

So I turned to the interpolate shape tool. I took the shapefile that had my survey lines in it, made a copy it for each DEM I have that I need to track the changes for and added z-values to each from the proper DEMs. But since these lines may encounter a dropped pixel or several, the resulting profile outputs are inaccurate. The distances of the lines are exaggerated at the locations where they encounter gap in the raster. A 9000m long survey line produces a 14,000m long profile graph with the extra 5000m appearing at the point where there was a small gap in the DEM. I can export this data as a CSV, load it into Excel, and then manually subtract the elongation from each affected cell, but that is very very time consuming.

There has to be a way to kick out a table of elevations along a line from a DEM without going down the profile graph path. Every spot in the raster has a X.Y. and Z value. I just need to know what those are along certain tracks.

Does anyone know of a script or workaround for Arc 10 that strips elevation data from either Polyline ZM shapefiles or from rasters and bypasses the 3D Analyst tool kit?

Any thoughts would be appreciated.

#2
spg

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ET Geowizards is able to strip the ZM values from a shapefile, I use it daily in 9.3.1. Try the ET Geowizards Site - it claims to work in 10.


Does anyone know of a script or workaround for Arc 10 that strips elevation data from either Polyline ZM shapefiles or from rasters and bypasses the 3D Analyst tool kit?

Any thoughts would be appreciated.



#3
Laura Miles

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I haven't tried it out, but I wonder if you could clean your raster up a bit first by converting it to points and then using one of the Raster Interpolation tools? That should clean up the gaps.
Laura




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