[GRASS-user] How to create 500m DEM from 90m DEM

[SGW00412 at nifty.com]

Dear Micha and all

Thank you for useful suggestions!

I studied new vector extent with v.in.region, and interpolation should be not 
vector but raster.

I'll try it, soon.

Best

Yasuo shimada: Japan weather association
---
Micha Silver <micha at arava.co.il>さん：
> On 01/01/2012 01:38 AM, SGW00412 at nifty.com wrote: 
> 
> Dear grass users;
> 
> I would like to create 500m dem from 90m dem (SRTM).
> 
> So, I am going to write a script as follows...is it right ?
> 
> 
> Here's how I would do:
> 1- Import the srtm, set resolution and region to this new raster:
> g.region -p rast=<srtm_raster>
> 
> 2- Get the current region extents:
> v.in.region out=srtm_region
> THis creates a vector rectangle of the current region
> 
> 3- Now switch to the UTM location, and project the original vector region to 
UTM...
> v.proj in=srtm_region loc=<wgs84_location> map=<wgs84_mapset> out=srtm_region
> ...and reset the current region to that new vector...
> g.region -p vect=srtm_region
> ...but also reset the resolution to 500 m...
> g.region -p res=500
> 
> 4- Now you can run r.proj to reproject the original srtm to your UTM region, 
and it will do the interpolation for you. The following quote is from the r.proj 
man page:
> "Note that, following normal GRASS conventions, the coverage and resolution of 
the resulting grid is set  by  the  current region  settings, which may be 
adjusted using g.region."
> ...so...
> r.proj in=<srtm_raster> loc=<wgs84_location> map=<wgs84_mapset> out=srtm_
raster_utm method=bilinear
> (You can choose which interpolation method to use, See the man page)
> 
> That should do it.
> --
> Micha
> 
> 
> (1)import with 'r.in.srtm' command.
> 
> (2)set resolution with 'g.region' command.
> SRTM is 90m resolution...
> 
> (3)exchagen a projection from latlon_wgs84 to utm_xx with 'r.proj' command.
> ( because initial projection of SRTM data is latlon_wgs84...)
> 
> (4)change resolution with 'g.region' res=500 (meter).
> 
> (5)create a point vector with 'r.to.v'(col=value) command.
> 
> I feel whether the target value is acquired by only change of resolution (90m-
>
> 500m). 
> 
> May I use 'r.surf.rst' ?
> 
> Best,
> Yasuo shimada: Japan weather associaton.
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