featureExtract

#featureExtract2.py
#Function to calculate NDVI from moasic raster and extract values associated with bare ground and impacted vegetation

import arcpy, sys, os
arcpy.CheckOutExtension("Spatial")

def meadowClip(inRast):
    '''Clipping moasic raster to boundary feature class(es).'''
    #List all feature classes that identify area of interest boundaries
    fcs = arcpy.ListFeatureClasses("*boundary*")

    #Clips the input raster to each boundary feature class listed
    for boundary in fcs:
        meadowBase = os.path.basename(boundary)
        outClipRast = meadowBase[:4] + "_OrthoClip.tif"
        arcpy.Clip_management(inRast, '#', outClipRast, boundary, "0", "ClippingGeometry")
        print "\t{0} created successfully.".format(outClipRast)


def calcNDVI(inClipRast, red, NIR):
    '''Using red and near infrared spectral bands from imagery
    to create a Normalized Difference Vegetation Index (NDVI) raster
    for area(s) of interest (e.g., orthophoto clipped to boundary).'''
    #Specify input raster and identify red and NIR bands
    inClipRastBase = inClipRast[:4]
    outNDVI = inClipRastBase + "_NDVI.tif"

    #Create output rasters and copy
    red_out = inClipRastBase + "_red.tif"
    NIR_out = inClipRastBase + "_NIR.tif"
    arcpy.CopyRaster_management(red, red_out)
    arcpy.CopyRaster_management(NIR, NIR_out)

    #Establish numerator and denomenator for map algebra and save result
    numerator = arcpy.sa.Float(arcpy.Raster(NIR_out) - arcpy.Raster(red_out))
    denom = arcpy.sa.Float(arcpy.Raster(NIR_out) + arcpy.Raster(red_out))

    NDVI = arcpy.sa.Divide(numerator, denom)
    NDVI.save(outNDVI)
    print "\t{0} created successfully.".format(outNDVI)

def extractValues(inNDVIRast):
    '''Extracting values identified as bare ground (e.g., values between -0.1
    and 0.1) from NDVI raster(s).'''
    inNDVIRastBase = inNDVIRast[:4]
    inSQL = "VALUE <= 0.1 and VALUE >= -0.1"
    bareOut = inNDVIRastBase + "_BareGround.tif"
    extractNDVI = arcpy.sa.ExtractByAttributes(inNDVIRast, inSQL)
    extractNDVI.save(bareOut)
    print "\t{0} created successfully.".format(bareOut)