# [vtkusers] Distance between 2 points in millimeters (mm)

Dominique Töpfer dominique at toepfer-web.de
Thu Aug 9 12:47:08 EDT 2012

Hi,

I think these lines in the for-loop are wrong:

points->GetPoint(num-1,punto);
points->GetPoint(num,punto2);

You seem to calculate the distance between the same two points in every
iteration. You need to use i instead of num here.

Regards,
Dominique

On 09.08.2012 18:34, Concetta Piazzese wrote:
> Hy everyone. I hope somebody can help me!
> I need to find the distance between 2 points in millimeters like the
> vtkDistanceWidget does. An user places 10 points and then the program
> compute the distances. The problem is that I have an array of
> vtkPoints and I can't use vtkDistanceWidget to find the distances. How
> I can find the distance? The points positions are inglobal coordinate
> values. The distance I got are totally wrong. Here is my code:
>
> int main(int argc, char *argv[])
> {
>
>
>     //Points Placement with vtkSeedWidget. Poins are stored in a
> vtkPoints called "points"
>     Seed();
>
>     double punto[3];
>     double punto2[3];
>
>     int num=points->GetNumberOfPoints();
>
>     for (int i=0; i<num; i++)
>     {
>     points->GetPoint(num-1,punto);
>     points->GetPoint(num,punto2);
>
>     double squaredDistance;
>     double dist;
>
>     // Distance
>     squaredDistance = vtkMath::Distance2BetweenPoints(punto, punto2);
>     dist=sqrt(squaredDistance);
>
>     std::cout << "Distance " << dist << std::endl;
>
>     }
>
>     return EXIT_SUCCESS;
> }
>
> What's the problem? vtkDistanceWidget computes distances using
> vtkMath::Distance2BetweenPoints. So what am I doing wrong?
> Thank you!
>
>
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--
Dominique Töpfer, Dipl.-Inform.
Institute of Medical Physics
University of Erlangen

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