pranjal004 Posted June 24, 2014 Report Share Posted June 24, 2014 Hey everyone, While calculation emissivity from NDVI index using Sobrino's method, it is clear what we have to do when NDVI is greater than 0.2. But when NDVI is less than 0.2, we are given an equation a + b®. where a and b are regression coefficients and R is the reflectivity. R can be calculated easily. How do we estimate or select the values of a and b? My project area also has water body which has a negative NDVI value. Please help! Quote Link to comment Share on other sites More sharing options...
Arhanghelul Posted June 24, 2014 Report Share Posted June 24, 2014 (edited) If NDVI values are lower that 0 (-0.1 to -1) we have water bodies. The emissivity value for water is 0.995. So, I think that the NDVI threshold should look like this: if NDVI is under 0 (negative values), then we have water > emissivity for water is 0.995 if NDVI is between 0 and 0.2, then we have bare soil > emissivity for bare soil is 0.97 if NDVI is > 0.5, then we have vegetation > emissivity for vegetation is 0.99 if NDVI is between the values 0.2 and 0.5 ( 0.2 ≤ NDVI ≤ 0.5), then we have a mixture of bare soil and vegetation > emissivity is calculated by the equation of Sobrino method Edited June 24, 2014 by Arhanghelul 1 Quote Link to comment Share on other sites More sharing options...
pranjal004 Posted June 25, 2014 Author Report Share Posted June 25, 2014 Ohhk Thanks Quote Link to comment Share on other sites More sharing options...
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