Dynamic band interpretation

Hi @jdh,

The RasterBandInterpretationCoercer uses the function @ReinterpretRaster. If we run this function in the FMEFunctionCaller transformer, we gain the ability to set the output raster type from a feature attribute.

We can use the RasterBandPropertyExtractor to determine the band type, then map that to its output type in a new attribute for the function.

I am attaching a workspace to illustrate the process.

changerastertype.fmw

Hi @jdh, I think you can implement that with Python. Example:

import fmeobjects
class FeatureProcessor(object):
    def __init__(self):
        interpretationPairs = {
            (fmeobjects.FME_INTERPRETATION_UINT8, fmeobjects.FME_INTERPRETATION_UINT16),
            (fmeobjects.FME_INTERPRETATION_INT8, fmeobjects.FME_INTERPRETATION_INT16),
            (fmeobjects.FME_INTERPRETATION_GRAY8, fmeobjects.FME_INTERPRETATION_GRAY16),
            (fmeobjects.FME_INTERPRETATION_RED8, fmeobjects.FME_INTERPRETATION_RED16),
            (fmeobjects.FME_INTERPRETATION_GREEN8, fmeobjects.FME_INTERPRETATION_GREEN16),
            (fmeobjects.FME_INTERPRETATION_BLUE8, fmeobjects.FME_INTERPRETATION_BLUE16),
            (fmeobjects.FME_INTERPRETATION_ALPHA8, fmeobjects.FME_INTERPRETATION_ALPHA16),
        }
        self.interpretations = {k : v for k, v in interpretationPairs}
        self.interpretations.update({v : k for k, v in interpretationPairs})
        self.rasterTools = fmeobjects.FMERasterTools()
        
    def input(self, feature):
        # Retrieve raster object from the input feature.
        raster = feature.getGeometry()
        if not isinstance(raster, fmeobjects.FMERaster):
            feature.setAttribute('fme_rejection_code', 'UNSUPPORTED_GEOMETRY_TYPE')
            self.pyoutput(feature)
        
        # Collect band objects and remove them from the raster.
        bands = []
        for i in range(raster.getNumBands()):
            bands.append(raster.getBand(0))
            raster.removeBand(0)
            
        # Update interpretation for each band and append them to the raster.
        for b in bands:
            before = b.getProperties().getInterpretation()
            after = self.interpretations.get(before, None)
            if after != None:
                b = self.rasterTools.convertBandInterpretation(after, b)
            raster.appendBand(b)

        # Reset raster to the feature.
        feature.setGeometry(raster)
        self.pyoutput(feature)
        
    def close(self):
        pass