[R-sig-Geo] Extract area of overlapping images

[Ned Horning]

Hi - I'm trying to extract the rectangle of pixels formed by the overlap 
of two images to try different image normalization techniques. I'm 
trying the following code but this results in integer vectors 
(image1subset and image2subset) of different lengths. I thought that by 
intersecting the two images and then applying that intersected area to 
the individual images I'd have two image subsets of equal size. I think 
I'm missing something basic. Can someone provide insight into how I can 
do this?

Thanks in advance,

Ned

--
image1Raster <- raster(image1)
image2Raster <- raster(image2)

NAvalue(image1Raster) <- 0
NAvalue(image2Raster) <- 0

intersect <- intersectExtent(image1Raster, image2Raster)

image1subset <- getValuesExtent(image1Raster, intersect)
image2subset <- getValuesExtent(image2Raster, intersect)