On Apr 17, 2012, at 4:48 AM, wanlin wrote:
Hi,
The current implementation of BoundaryFacesCalculator is based on
the following assumption.
There is an overlap between requestToProcessRegion and
nonBounaryRegion of BufferedRegion.
Hence the first region in the output list is the nonBoundaryRegion
in requestToProcessRegion.
In your test, there is no overlap between requestToProcessRegion and
bufferedRegion since requstToProcessRegion index[Dimension-1] = 1,
which bufferedRegion index[Dimension - 1] = 0, size[Dimension - 1]
= 1, . The ideal results ought to output 0 regions.
Should we change the implementationso the calculator could deal with
any cases of requestToProcessRegion and BufferedRegion? I am willing
to put a patch.
thanks
wanlin
I don't think the correct answer is 0 regions if the purpose of the
calculator is to break the image up into regions for iteration. The
best way to tell that it is working is that each pixel in the image
should be visited once and only once when iterating across the union
of the regions returned by the calculator.
Let's look at two 2-D cases, a) [5,5] and b) [5,1].
In case a) the calculator returns the following regions:
Index[1, 1], Size [3, 3], 9 pixels
Index[0, 0], Size [1, 5], 5 pixels
Index[4, 0], Size [1, 5], 5 pixels
Index[1, 0], Size [3, 1], 3 pixels
Index[1, 4], Size [3, 1], 3 pixels
So all 25 pixels are visited once
In case b), the calculator currently returns:
Index[1, 1], Size [3, 0], 0 pixels (I think it is ok to return an
empty region here as it indicates there are no interior points in the
image)
Index[0, 0], Size [1, 1], 1 pixel
Index[4, 0], Size [1, 1], 1 pixel
Index[1, 0], Size [3, 1], 3 pixels
Index[1, 0], Size [3, 1], 3 pixels
So 8 pixels are visited when there are only 5 pixels in the image.
-Kris
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