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I'm trying to compute a MTVI2 (Modified Triangular Vegetation Index - Improved) and EVI (Enhanced Vegetation Index) from Landsat 8 imagery.

My formulas are as follow (I'm using ModelBuilder):

MTVI2=

1.5*(1.2*("%Band 5%"-"%Band 4%")-2.5*("%Band 4%"-"%Band 3%")) / SquareRoot(Square(2*"%Band 5%"+1)-(6*"%Band 5%"-5*SquareRoot("%Band 4%")-0.5))

EVI=

("%Band 5%"-"%Band 4%") / ("%Band 5%"+6*"%Band 4%"-7.5*"%Band 2%"+1)

I've tried threating the bands as floats with the same results. Any suggestions?

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    The labels in percents are variables that should be somewhere else in your model... try to break it down into smaller temporary rasters so you can see each step. Are you getting an error message or do you not get your intended results? – Michael Stimson Jul 3 '15 at 1:34
  • Yes, the variables (bands) are selected when the model is initiated. I tried this approach but you get the same results. I do not get any errors nor the expected results. I think there is something wrong with the map algebra rules but I can't identify the problem. – Julio A. López Jul 3 '15 at 3:15
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    Breaking your calculations down into smaller steps then comparing the source with the destination (doing the calcs manullay for a few cells) will prove that the values are correct... after you've done that you can then combine them into a single calculation again but put brackets around each sub raster calc to distinguish it. – Michael Stimson Jul 3 '15 at 4:07
  • So you have turned your model into a Model Tool and the user selects each raster which represents a single band? Please confirm that %Band 5% is a raster dataset (which it must be) and not a number, in this case 5. – Hornbydd Jul 3 '15 at 10:55
  • I confirm all of them are raster datasets (band 5, 4 and3). I tried manual raster calculation and separated computations with the same result. The expected result for the mtvi2 should be a single band raster ranging from -5 to 5 +/-2 depending on vegetation. The obtained results is a single band raster ranging from -1600 to ~13000, in the histogram most values (if not all) are -1600. – Julio A. López Jul 3 '15 at 13:24

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