I have sample points (shape file converted from a .xls file which contains XY coordinates,nnx,nny and canopy density) and a landsat etm+ image. First I applied 'SpatialAnalyst Tools>Extraction >Sample' in ArcGIS in order to extracted spectral signatures of all sample points from Landsat image. I then exported output to a DBF file and opened it in Excel. The DBF file has XY coordinates of sample points and NP_2001102,NP_2_30513,NP_2_30514,NP_2_30515,NP_2_30516 and NP_2_30517. I assume e.g. NP_2_30513 is band 3 and NP_2_30514 is band 4.
So the question is: 1), are they really band 3 and band 4? 2), if they are, and if I want to calculate NDVI values and then do linear regression between canopy density and NDVI in Excel, what should I do to get correct reflectance values before the calculation?
Examples of values of NP_2_30513 are 11, 9, 13, 8...etc., examples of values of NP_2_30514 are 10, 7, 7, 4, ...etc.
I know these values are not really reflectance values, but how can I get the correct values for my calculation and regression?