[GRASS-user] low radiance values after i.atcor and i.topo.corr

[maning sambale]

Thanks!  Multiplying by 1000 with r.mapcalc gives better results.  Any
chance adding floating points (FCELL) to i.cluster?

On 6/16/08, Markus Neteler <neteler at osgeo.org> wrote:
> On Mon, Jun 16, 2008 at 11:59 AM, maning sambale
> <emmanuel.sambale at gmail.com> wrote:
>> After implementing gain and bias correction and topographic
>> correction, I get very low values for landsat data data
>> for example range of values of band1:
>>
>> GRASS 6.3.1svn (p112r056):~ > r.info lsat7_2000.toar.1 -r
>> min=0.030303
>> max=0.372067
> ...
>> Running these range of values to an i.cluster reports very low
>> separability:
>
> As far as I see it is related to the fact that i.cluster reads in as
> integer (CELL)
> through G_get_c_raster_row():
>  http://download.osgeo.org/grass/grass6_progman/gis_2get__row_8c.html
> ...
>> I assume this is due to the very low range of values (0.0xxx) of the
>> input images.  Running r.rescale.eq to "stretch" the range of values
>> doesn't also help.
>
> You may try to multiply the values with 100 or 1000 using r.mapcalc.
>
> Please let us know how it works.
>
> Markus
>


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