Typ radiometrické veličiny

FranciscoCáceresClavero

Mám kameru Micasense Rededge-P vybavenou senzorem Downwelling Light Sensor (DSL2), který měří okolní světlo a úhel slunce pro každý z pěti pásů kamery a zaznamenává tyto informace do metadat TIFF snímků pořízených kamerou. Také mám kalibrační panel a fotografuji ho při každé letové misi.<\/P>

1) Jaký typ radiometrické veličiny bych měl použít, pokud chci zohlednit hodnoty osvitu poskytnuté DSL2 zaznamenané v metadatech obrázku?
2) Existuje typ radiometrické veličiny, který umožňuje společné použití dat z DSL2 a kalibračního panelu? <\/P>

CodyBinkelheim

Francisco

for Radiometric Quantity Type you should use Reflectance.  See help here: 

https://doc.arcgis.com/en/drone2map/latest/help/radiometric-calibration.htm

At this time we have not implemented support for the DLS inside Drone2Map.  What I would recommend is to capture images of the reflectance panel before and after your flight, and look at the DLS values for those calibration images and also for the images captured over your project site.  If the "before" and "after" calibration images have DLS values that are very similar (within a few %) and your flight images show consistent DLS values, your results should still be valid.  

If the DLS data indicates significant changes during the flight (perhaps more than ~15%, but this is just an estimate) then you would need to consider how changes in your multispectral values from early vs. late in the flight may appear in your data.  e.g. if your flightlines run north/south and proceed from west to east, and illumination drops by 15% from first image to last, your spectral values MAY show a bias from west to east.

However, if you're using NDVI, this concern is largely reduced, since the normalization of the NDVI compensates for variable illumination.  Further, your drone will most likely change the exposure parameters to compensate for the change in illumination.