<br><br><div class="gmail_quote">2011/5/24 Markus Neteler <span dir="ltr"><<a href="mailto:neteler@osgeo.org">neteler@osgeo.org</a>></span><br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
On Tue, May 17, 2011 at 10:57 PM, Elena Mezzini <<a href="mailto:elena.mezzini@gmail.com">elena.mezzini@gmail.com</a>> wrote:<br>
> Elena Mezzini wrote:<br>
<div class="im">>> Markus Metz-2 wrote:<br>
>>><br>
>>> On Tue, May 17, 2011 at 10:08 PM, Elena Mezzini<br>
</div><div class="im">>>> &<a href="mailto:lt%3Belena.mezzini@gmail.com">lt;elena.mezzini@gmail.com</a>&gt; wrote:<br>
>>>><br>
>>>> On Tue, May 17, 2011 at 9:22 PM, Elena Mezzini<br>
>>>> &<a href="mailto:lt%3Belena.mezzini@gmail.com">lt;elena.mezzini@gmail.com</a>&gt; wrote:<br>
>>>>> Hi all,<br>
>>>>> I'm once again in trouble with i.atcorr in GRASS6.5.svn.<br>
>>>>> I notice that my output reflectance images are strange: there are some<br>
>>>>> areas<br>
>>>>> that are really bright and other that are really dark. Both seem to<br>
>>>>> match<br>
>>>>> with my DEM raster.<br>
>>>>> Could there be problems with negative values in DEM?? I'm in a coastal<br>
>>>>> area<br>
>>>>> and there are some real altitude negative values.<br>
</div>...<br>
...<br>
<div class="im">>> g.region rast=dem_sross_srtm<br>
>> r.mapcalc "dem_sross_srtm_pos = if(dem_sross_srtm < 0, 0, dem_sross_srtm)"<br>
</div>...<br>
> No differences between negative and positive values...<br>
<br>
What do you mean precisely?<br>
<font color="#888888"><br>
</font></blockquote></div><font class="Apple-style-span" face="georgia, serif" color="#990000">I mean that i.atcorr automatically considers negative values equal to 0. So the results of i.atcorr with negative values or with negative values made equal to zero are the same.</font><div>
<font class="Apple-style-span" face="georgia, serif" color="#990000">So I still have problem with all the bands of landsat probably due to DEM.</font></div><div><font class="Apple-style-span" face="georgia, serif" color="#990000"><br>
</font></div><div><font class="Apple-style-span" face="georgia, serif" color="#990000">Elena</font><br><br>
</div>