[vtkusers] [vtk-developers] vtkCell::IntersectWithLine issues

[Will Schroeder]

"From these faces I choose the one that is nearer to the
end point of the ray and the next cell to search is the cell adjacent to the
chosen face."

What does it mean to have a face nearer to an end point? How are you
determining this? This is not as straight frward as it sounds and could be
an issue.

W

2008/7/1 Kaushik . <shekhar.kaushik at gmail.com>:

> Hi
>
> I am trying to implement the following algorithm and I am stuck. I need to
> cast rays
> from each pixel into a dataset. Along each ray , I need to find the first
> cell that satisfies
> some characteristics. I go about implementing it as follows :
> Using the vtkCellLocator::IntersectWithLine() , i find the first cell the
> ray intersects in the dataset.
> If this cell satisfies the conditions , we exit.
> else we continue searching cells along the ray until one such cell is found
> , or until we eventually reach
> the boundary of the dataset.
> Now this searching cell along a ray is causing me trouble. Given the first
> cell that the ray intersected,
> I find the faces of the cell that the ray intersects. From these faces I
> choose the one that is nearer to the
> end point of the ray and the next cell to search is the cell adjacent to
> the chosen face.
> The algorithm seems to be correct logically atleast.
>
> The vtkCell::IntersectWithLine() functions however seem to be giving
> inconsistent results ! Are there
> any known issues with these functions ? Please advise.
>
> Also can you please comment on the algorithm above ? Is there any other
> way( better ? ) to do the same ?
>
> --
> shekhar
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>
>


-- 
William J. Schroeder, PhD
Kitware, Inc.
28 Corporate Drive
Clifton Park, NY 12065
will.schroeder at kitware.com
http://www.kitware.com
518-371-3971 (phone and fax)
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