[Insight-developers] boundary faces calculator bug

[wanlin]

In the case of [5,1], the image bufferedRegion is index[0,0], size[5,1].
requestToProcessRegion is the same as bufferedRegion.
There is no NonBoundaryRegion with radius[1,1]. Meanwhile there is only one
boundary region in the Y direction.

I submit a patch which could address the issue.  However it could not
handle requestToProcessRegion is inside of BoundaryRegion.

best


wanlin

On Wed, Apr 18, 2012 at 12:35 AM, Kris Zygmunt <krismz at sci.utah.edu> wrote:

>
> 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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