[GRASS-dev] r.horizon -> G_set_window (maybe) error in southern hemisphere

[Yann Chemin]

2009/6/22 Hamish <hamish_b at yahoo.com>:
>
> Yann Chemin wrote:
>> Made a map in Australia, and wanted to use r.horizon on it.
>> Nothing special, a srtm map and default conditions.
>> This is the output:
>>
>> (Sat Jun 20 16:51:57 2009)
>> r.horizon elevin=dem25m at PERMANENT horizonstep=30 bufferzone=200
>>   maxdistance=2000 horizon=horangle
>> G_set_window(): Illegal latitude for North
>> (Sat Jun 20 16:51:57 2009) Command finished (0 sec)
>
> I can recreate this from a single Lat/Lon srtm file. Works fine if you
> reproject it into a planimetric map projection. --->
>
> from the man page:
> "At the moment the elevation and maximum distance must be measured in meters, even if you use geographical coordinates (longitude/latitude). If your projection is based on distance (easting and northing), these too must be in meters. The buffer parameters must be in the same units as the raster coordinates."
>
> i.e. for a lat/lon location bufferzone=200 makes the buffer 200 degrees
> in all directions, not 200m.
>

OK, I'll try modifying this.

> otherwise, man page indicates it should work ok with lat/lon.
>
>
>> rows:       52968
>> cols:       39853
>> cells:      2110933704
>
> I hope you have a fast computer!
>

... Sigh! Definitely not, but it will have to do, as usual.

>
> aside- perhaps the code should use G_distance() instead of its own
> semi-baked distance() function??
>

Would be good for homogeneity of the code.

>
> Hamish
>
>
>
>
>
>

Thanks a lot Hamish.

-- 
Yann Chemin
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