[Qgis-user] Grid creation and export data to *.asc

[Luciano La Sala]

Hello again…! 

 

In doing as Micha advises I came across the following cryptic warning: 

 

Cannot start module r.out.xyz. command: C:/OSGeo4W/apps/grass/GRASS-~1.2/bin/r.out.xyz.bat --interface-description
0 [main] us 0 init_cheap: VirtualAlloc pointer is null, Win32 error 487 AllocationBase 0x0, BaseAddress 0x71110000, RegionSize 0x460000, State 0x10000 C:\OSGeo4W\apps\msys\bin\sh.exe: *** Couldn't reserve space for cygwin's heap, Win32 error 0

 

If I go ahead a hit “run” I get the following output: 

 

r.out.xyz 

0 [main] us 0 init_cheap: VirtualAlloc pointer is null, Win32 error 487

AllocationBase 0x0, BaseAddress 0x71110000, RegionSize 0x460000, State 0x10000

C:\OSGeo4W\apps\msys\bin\sh.exe: *** Couldn't reserve space for cygwin's heap, Win32 error 0

Finished with error 

 

I have no idea what the problem is this time. Any help will be more than welcome. 

 

Thank you very much in advance. 

 

Luciano 

 

 

De: Micha Silver [mailto:micha at arava.co.il] 
Enviado el: Friday, December 21, 2012 2:30 PM
Para: Luciano La Sala
CC: qgis-user at lists.osgeo.org
Asunto: Re: [Qgis-user] Grid creation and export data to *.asc

 

Hi Luciano

On 12/21/2012 5:30 PM, Luciano La Sala wrote:

Hello Folks, 

Sorry to re-send but I got no response and I am not sure why. If my question was not clear I can always rewrite it. Luciano 

 

Hello QGIS users, 

I have a raster image of human population counts (LandScan) of approximately 1 km resolution. I need to take each cell of the raster one by one and retrieve the population count for that cell. 

To do this, I was told to create a grid theme of population density - based on the grid themes specifying population counts and area.

Export population count and population density files from ArcView to *.asc files.

 

Since your Landscan grid is at resolution 1 km, then the population count and density (per sq km) should be the same.

Using the GRASS module r.out.xyz you can get an ASCII text file with three columns: X,Y,value. The X-Y are cell enters, and value would represent Population count.

 

I am not sure how to create the grid nor how to export pop count and density files to *.asc. Any tips? Thank you in advance! 

Luciano La Sala



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