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dvalters / HAIL-CAESAR

The High-Performance Architecture-Independent LISFLOOD-CAESAR model of floodplain, river, and sediment dynamics
http://dvalters.github.io/HAIL-CAESAR
GNU General Public License v3.0
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how to generate the DEM input files(.asc) #29

Closed Dongxueyang closed 3 years ago

Dongxueyang commented 5 years ago

When I build a new project to make a simulation. I have to write DEM input file as ascii format. I open the file and see some data about the elevation. But I want to know the meaning of the variable such as: ncols, nrows, xllcorner,yllcorner,cellsize,NODATA_value. And other data is similar about pixel （0-255），is there any connection between the pixel with elevation? How can I generate this DEM file? Can anybody help me?

best regards

dong dxy159753@sina.com

Dongxueyang commented 5 years ago

@dvalters

tcoulthard commented 5 years ago

It’s a standard arc-gis ascii format. Google that and you’ll find out what the header contains.

On 4 Aug 2019, at 06:41, Dongxueyang notifications@github.com<mailto:notifications@github.com> wrote:

When I build a new project to make a simulation. I have to write DEM input file as ascii format. I open the file and see some data about the elevation. But I want to know the meaning of the variable such as: ncols, nrows, xllcorner,yllcorner,cellsize,NODATA_value. And other data is similar about pixel （0-255），is there any connection between the pixel with elevation? How can I generate this DEM file? Can anybody help me?

best regards

dong dxy159753@sina.commailto:dxy159753@sina.com

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dvalters commented 5 years ago

@Dongxueyang as Tom says, the header info is a standard format, i.e.: http://resources.esri.com/help/9.3/arcgisengine/java/GP_ToolRef/spatial_analyst_tools/esri_ascii_raster_format.htm

The pixel value should be the elevation (usually in metres) (0-255 almost seems like it is some sort of colour band range, (8-bit colour map would be 256 values...?) but could be coincidental) so check you haven't exported the colour map as the raster by mistake.