[vtkusers] Only half of pixels shown on border of Image.

[sandarak at wp.pl]

Hi Lisa,

Thank you for explanation of this problem and your suggestion about
solving it.

Regards

Michal


> Hi Michal,

> This is the expected behavior of vtkImageActor. The issue is that in VTK
> the image is considered to go from the location of the first sample to the
> location of the last sample along some axis (if you have N samples, and a
> spacing of D, you have a distance of (N-1)*D between the first and last
> sample). Each internal sample (other than the first and last) impacts a
> linear distance of D, with the first and last sample each impacting 1/2 D.
> This keeps the total distance (N-1)*D. This makes sense and looks correct
> for linear interpolation, but does look strange for nearest neighbor
> interpolation since the edge pixels look to be cut in half. However,
> vtkImageData has point scalars, not cell scalars - so the value is 
> associated with the point, and not the cell (space between points). If you
> have such a small image and you want to display it using cell scalars, I
> would recommend using a set of quads with associated cell scalars.

> Lisa


> At 03:42 PM 5/18/2005, sandarak at wp.pl wrote:
>>Hello!
>>
>>When I'm trying to show very small image ( 5 x 5 ), with vtkImageActor
>>the pixels on the border of the image are half-cut (I can see that
>>clearly because the interpolation is turned off). How can I show whole
>>pixels on border? Does it have anything to do with clipping?
>>
>>Thank you in advance
>>
>>Michal
>>
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