[GRASS-user] Re: i.atcorr negative DEM

[Markus Neteler]

On Tue, May 17, 2011 at 10:57 PM, Elena Mezzini <elena.mezzini at gmail.com> wrote:
> Elena Mezzini wrote:
>> Markus Metz-2 wrote:
>>>
>>> On Tue, May 17, 2011 at 10:08 PM, Elena Mezzini
>>> &lt;elena.mezzini at gmail.com&gt; wrote:
>>>>
>>>> On Tue, May 17, 2011 at 9:22 PM, Elena Mezzini
>>>> &lt;elena.mezzini at gmail.com&gt; wrote:
>>>>> Hi all,
>>>>> I'm once again in trouble with i.atcorr in GRASS6.5.svn.
>>>>> I notice that my output reflectance images are strange: there are some
>>>>> areas
>>>>> that are really bright and other that are really dark. Both seem to
>>>>> match
>>>>> with my DEM raster.
>>>>> Could there be problems with negative values in DEM?? I'm in a coastal
>>>>> area
>>>>> and there are some real altitude negative values.
...
...
>> g.region rast=dem_sross_srtm
>> r.mapcalc "dem_sross_srtm_pos = if(dem_sross_srtm < 0, 0, dem_sross_srtm)"
...
> No differences between negative and positive values...

What do you mean precisely?

Markus