1

i have to derive NDVI from Landsat 8 image..
I used the following equation from landsat website with band 5 and band 4 using ArcGIS 10.1
Conversion to TOA Radiance
OLI and TIRS band data can be converted to TOA spectral radiance using the radiance rescaling factors provided in the metadata file:

Lλ = MLQcal + AL   

where:                

Lλ          = TOA spectral radiance (Watts/( m2 * srad * μm))
ML         = Band-specific multiplicative rescaling factor from the metadata (RADIANCE_MULT_BAND_x, where x is the band number)
AL          = Band-specific additive rescaling factor from the metadata (RADIANCE_ADD_BAND_x, where x is the band number)
Qcal        = Quantized and calibrated standard product pixel values (DN)         



Conversion to TOA Reflectance

ρλ' = MρQcal + Aρ 

where:              

ρλ'          = TOA planetary reflectance, without correction for solar angle.  Note that ρλ' does not contain a correction for the sun angle. 
Mρ         = Band-specific multiplicative rescaling factor from the metadata (REFLECTANCE_MULT_BAND_x, where x is the band number)
Aρ          = Band-specific additive rescaling factor from the metadata (REFLECTANCE_ADD_BAND_x, where x is the band number)
Qcal        = Quantized and calibrated standard product pixel values (DN)

But the final result have negative values in both sides.
Can any one tell how to solve this problem?

closed as unclear what you're asking by PolyGeo Sep 18 '16 at 5:02

Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

  • What were the precise steps (all tools and parameter values) that you used when you tried to do this? – PolyGeo Sep 18 '16 at 5:02