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

Concetta Piazzese aliens30586 at hotmail.it
Thu Aug 9 12:34:42 EDT 2012

```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;
double punto2;

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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