[GRASS-user] errors in m.proj

[Hamish]

Reno Bladergroen wrote:

> The landsat maps i downloaded are in XY-meters projection. I also
> downloaded SRTM-3arc data and those are in LL projection. So when
> i want to import all these data in my location database I get
> errors: projections don't match. I prefer LL projection so
> thought: lets use m.proj to convert all XY data to
> LL projections. When I do this I get the following error:
>  
> Assuming current projection as input, LL WGS84 as output.
> 
> input parameters=[+proj=utm +no_defs +zone=32 +a=6378137
> +rf=298.257223563
> +towgs84=0.000,0.000,0.000 +to_meter=1]
> 
> output parameters=[+proj=longlat +towgs84=0.000,0.000,0.000]
> 
> input file=[/Users/Reno/Documents/Personal files/Zweefvliegen/Scenery
> project/p197r025_7p20000911_z32/p197r025_7t20000911_z32_nn10.tif]
> tr: Illegal byte sequence
> 4d30'40.522"E	0dN 0.000
> 
> Then when I tried to convert the SRTM data to XY-meters, I also got
> the last line error: tr: Illegal etc.
> 
> What did I do wrong?

m.proj is for a list of individual coordinates (like GPS waypoints).

You want r.proj.  (pulls map into the current location/mapset, so
import SRTM into UTM location, then in the LL location pull it across
with r.proj)


> Then one more thing: I downloaded finished SRTM data from CGIAR.
> These maps do cover half the continent :confused:, so the region
> is not corresponding to my working region. How can i still use this
> data?

If there is coverage overlap use g.region to set bounds. If you need
data which isn't there you'll have to obtain the next tiles from
another source. 

Note a single zone UTM projection is only valid east-west for about
half a continent, at the most, and most SRTM data I have seen was
already in lat/lon. Beyond the 6-degree band you get worse and worse
distortion.


> still waiting for the book...

See Markus's earlier post today.


Hamish





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