[Gdal-dev] how to get pixels' band vector efficiently

[Andrew Finley]

Hi All,
I have written an image classification algorithm which uses gdal to fill
a vector of band values for each pixel.  I'm looking for a better/faster
way of accessing these values. Two general ways I might think to speed
this up are: 

1) move one tile at a time into memory then apply the loop below.
2) find a way to load my target vector more efficiently than one
pixel/layer at a time.

So I guess I'm looking for some ideas or example code.  Could the
tileindex application offer any help? Does it load logical image blocks
(i.e., from a single page)?

Thanks a lot for suggestions.
-Andy

Current approach:
//every pixel loop
for (int row = 0; row < featureDataset->GetRasterYSize(); row++){
	for (int col = 0; col < featureDataset->GetRasterXSize(); col++){

	//fill targetBandVec
	for (layer = 1; layer <= featureDataset->GetRasterCount(); layer++){
		featureBand = featureDataset->GetRasterBand( layer );
		featureBand->RasterIO(GF_Read, col, row, 1, 1, featurePixel, 1, 1,
GDT_Float32, 0, 0 );
		targetBandVec[layer-1]=featurePixel[0];
	}

	Then classify the target vector...

	}
}


-- 
Andrew Finley, Research Fellow
Department of Forest Resources
College of Natural Resources           
University of Minnesota
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1530 Cleveland Avenue N.
St. Paul, MN 55108

Ph 612-624-1714 office
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