Creating NDVI map without cloud cover

[LisaHuttenlocher]

Hey guys,

i´m trying to create an NDVI map from Landsat 8 OLI images by using raster calculator witth the NDVI formula (NIR-Red / NIR+Red).

So far it worked out pretty good, but I have a few clouds in my satelllite data which I´m trying to mask out.

I already used the QA band for cloud and cloud shadow masking, but I don´t know how to apply it on my calculations.

I tried to put the cloud values to zero, but then I get NDVI values which ranges from -110 to 32. So I think this way doesn´t work properly.

I would be grateful on suggestions on how to handle cloud cover in NDVI calculations.

Thank you in advance!

[DanPatterson_Retired]

mask the clouds with 'nodata' and not 0 since 0 is a valid number.  nodata cells will not be included in calculations

[LisaHuttenlocher]

Hello Dan,

sorry, that is actually what I did. Cloud cover values have "nodata" in my raster.

I dont really understand why I get these results because the values in NIR band range from -0.1 to 0.8 and in the RED band from -0.1 to 0.7. Clouds have no data and anyways the NDVI ranges from -110 to 32.

[DanPatterson_Retired]

When you say 'mask' those areas should not be used in the calculation at all.  It sounds like you aren't setting a mask  in your Environments setting and/or you haven't assigned nodata to the areas covered with cloud... which should propagate through all the bands., so check each band.