model builder to create NDVI

DavidAinley1 — Mon, 06 Oct 2014 14:53:18 GMT

I need to create an NDVI from multiple NAIP images and I will need to do it 3 or 4 times in the next year or 2.

I have all the imagery in a folder which (I think) I will iterate through... but I need to generate an output in order to pull the bands I need into the raster calculator. advice?

Thanks,

Hank

Re: model builder to create NDVI

curtvprice — Wed, 08 Oct 2014 21:39:00 GMT

My advice, first build a model that will work on one raster, then worry about iteration after that.

You may need to use the Calculate Value tool to pull out the paths of the band in the NAIP image. In the example below, I'm assuming you have a model element set up (of type Raster Layer) called "NAIP raster".

Calculate Value parameters:

Expression:

f(r"%NAIP raster%")

Code block:

import os
import arcpy
def f(raster):
  raspath = arcpy.Describe(raster).catalogPath
  return os.path.join(raspath, "Band_1")

Data type:

Raster Dataset

You would need one of these for each band. In ModelBuilder, they should be available for use in the Raster Calculator tool.

If you get this working, you could nest this model inside another one that uses Iterate Rasters to run each raster in the folder in turn.

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model builder to create NDVI

Re: model builder to create NDVI