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I recently downloaded a GeoTIFF 1 arc second from the USGS National Map Viewer. I added the raster to ArcScene and attempted to visualize the data in 3D. I set the Base Height to Floating on a Custon Surface, changed the Resolution to that of the Original Surface (3612 rows and columns; 0.000278 cell size). However, when it's done processing, my DEM just looks a mess; there are giant spikes all through the data. I've tried downloading DEMS from other areas and repeating the process but I get the same result.

What am I doing wrong? I suspect perhaps there are Null values but I'm not sure. Any help would be greatly appreciated.

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2 Answers 2

You've got a projection issue. Chances are you've not specified the projection of the DEM correctly. There are typically two indicators to this and you have both:

  • You have spikes.
  • You have a cell size that looks like: 0.000278 (it should be a whole number).

So make sure you've set the correct projection for the DEM as well as the drape (if memory serves, the issue is mostly DEM side).

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Yes I believe DEMs from the national map come in lat long coordinates but lack horizontal distance units, therefore reprojecting the DEM should be the way to go. –  egdetti Oct 17 '12 at 14:00
    
Thanks Jonathan - I projected the data to UTM using the Project Raster tool and still have the same problem so I'm assuming that it must be a problem with the cell size. Do you know how that can be fixed? I saw that I can change the cell size when I project the raster but doing this changed the values to 26.81883836 and still created spikes when I set the base height and resolution. –  Ashley Oct 17 '12 at 14:16
    
@Ashley - I don't have ArcScene, its been a few years, but I don't think there's anything wrong with the cell size - that's a symptom of the problem rather than the problem itself. I'd go with edgetti and reproject the entire DEM to hopefully resolve the issue. –  GIS-Jonathan Oct 17 '12 at 15:38
    
Thank you both - I got the projection to work. The problem was that I didn't have the Scene Layer (Data frame) coordinate system matching the newly projected layer. Thanks again for letting me to know to first project the data. I really appreciate it. –  Ashley Oct 17 '12 at 16:18

I just had the same problem as you but had a different solution.

In scene properties I changed the "Vertical Exaggeration" to "Geographic"

(i know the question was asked a while ago but this offers another explanation.

(Im using Arc Scene 10.1)

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