Creating Pecube input topography files from ArcGrid files

·The purpose of this file is to explain how to generate topography files that can be read into Pecube from ArcGIS ArcGrid files

** OLD METHOD BELOW ** Should still work, see other method on previous page.

1.Open ArcGRID in a new command window in windows

• Click on the Start button, then on Run...
• type 'cmd'
• change to the directory with your ArcGrid folder

·cd “C:\path\to\folder”

• type 'arc', followed by 'grid' once ArcInfo starts

2.Create a 3 column ASCII file from your ArcGrid file

·<file>.xyz = sample (<gridfile>)

3.Copy the output 3 column ArcGIS file to the Pecube working directory

4.Run make_topo.sh and give the Arcgis file as input and any filename as output

5.Open Pecube.in and change the topography file used (option 2) to be the output file created from make_topo.sh

6.Change the number of longitude and latitude points to those printed when make_topo.sh is run

7.Change longitude and latitude spacing to the values make_topo.sh gives

Note:

·VERY IMPORTANT:

·You must set the coordinate system origin in the Pecube.in file to be offset from zero by half the resolution of the DEM you input to have the topography in the correct locations

·e.g.: If your DEM has a 250 m resolution, your coordinate system origin would be 125, 125 m

·The product of the longitude and latitude points, set in Pecube.in, must not exceed the number of topography values in the input topography file.The finite element model (FEM) mesh cannot be at a finer resolution than the digital elevation model (DEM)

·If the product is smaller, Pecube will still run.However, the topography read in by Pecube will be garbage.This means that the extent of the topography file from Arcgis must be equal to the size of the FEM.

·Note: You can use a more coarse FEM mesh but the mesh must be a multiple of the DEM resolution (e.g. skipping factor in Pecube.in file)

·Make sure to set input unit type (degrees or kilometers) to match the topography file generated