8 replies to this topic

[Rusty]

Hello All,
Just wondering if anyone has had experience in manipulating 30m elev. rasters? I am generating spill plumes using ArcInfo and have a NED dataset and cut rasters to an area...so by a tank farm they have built up dams along a river so I need to reflect this by somehow changing the elev. of the pixels...is there a tool out there to do this?

Thanks,
Rusty

[Bryan Swindell]

Using ArcGIS desktop (any license level), I would digitize the dams as a polygon shapefile, making sure they are at least 30m wide. Convert them into rasters via the Spatial Analyst toolbar. Make sure your raster settings are set to match the extent and resolution of the DEM (30m).

Then, assign the dam pixels higher elevation values than the surrounding terrain. All others get a 0. Finally, add the dam raster and the DEM together. Those pixels that are 'dam' will have higher values than the surrounding terrain. You can do all these steps using Spatial Analyst.

[johnnyh]

hm... these new dams you have a spatial layer for them with elevation? If so, you could probably convert them to raster and do some raster calc work to update your DEM.

[Charles Syrett]

I don't know how you would do this in Arc, but in Global Mapper you would just add the dams as polylines and then give each vertex a z value. You could then generate a new DEM from the original DEM, using the polylines as breaklines. I'm sure there must be a process like this within Arc.

Charles Syrett
Map Graphics
http://www.mapgraphics.com

Hello All,
Just wondering if anyone has had experience in manipulating 30m elev. rasters? I am generating spill plumes using ArcInfo and have a NED dataset and cut rasters to an area...so by a tank farm they have built up dams along a river so I need to reflect this by somehow changing the elev. of the pixels...is there a tool out there to do this?

Thanks,
Rusty

[johnnyh]

Wow, Charles, GMapper sure has come a long way... Very impressive program. So simple and lightweight compared to Arc.

I'm going to have to get my boss to buy me the new version.

[Charles Syrett]

Right -- Global Mapper isn't a full blown GIS like Arc or Manifold, but it does a lot of stuff like this very nicely. Like using a bicycle to take a shortcut across a field (but not to go onto a freeway)!

Charles Syrett
Map Graphics
http://www.mapgraphics.com

Wow, Charles, GMapper sure has come a long way... Very impressive program. So simple and lightweight compared to Arc.

I'm going to have to get my boss to buy me the new version.

[Rusty]

thanks guys I'll give it a try...wow I can download a trial version of Global Mapper...

[Bryan Swindell]

Rusty - you could also try posting this on the ESRI user's forum. There are a lot of DEM-gurus over there that might have some other ArcGIS-based novel solutions you could try.

[Rusty]

Rusty - you could also try posting this on the ESRI user's forum. There are a lot of DEM-gurus over there that might have some other ArcGIS-based novel solutions you could try.

will do..Thanks