On Thu, Jun 6, 2019 at 6:28 PM Markus Metz <[email protected]> wrote:
> Hi Madi, > > On Thu, Jun 6, 2019 at 4:13 PM Margherita Di Leo <[email protected]> > wrote: > > > > Hi, > > > > reading the training material here: > http://training.gismentors.eu/grass-gis-irsae-winter-course-2018/units/23.html > > I have a doubt. When cloud mask is applied to calculate NDVI > > > > t.rast.mapcalc input=b4,b8,cloud output=ndvi_cloud \ > > expression="if(isnull(cloud), null(), float(b8 - b4) / ( b8 + b4 ))" \ > > basename=ndvi_cloud nproc=3 > > > > what happens if there is no cloud mask at all for a certain map? In this > case NDVI should be taken as is. Instead, to my understanding, what happens: > > > > if(isnull(cloud), null() > > > > If cloud map is not found (meaning there is no cloud detected), > isnull(cloud)=True, so the NDVI resulting map is null too. Please correct > me if I'm wrong. > > the cloud masks are apparently created with "sentinel-cloud-mask.py" which > requires an AOI vector as input, and a cloud mask is always generated: if > there are no clouds or no cloud mask, only the AOI is used as mask. > > from a quick glance at "sentinel-cloud-mask.py" > > Markus M > > Thank you Markus! -- Margherita Di Leo
_______________________________________________ grass-user mailing list [email protected] https://lists.osgeo.org/mailman/listinfo/grass-user
