[vtkusers] Curve / Equal Subdivision

[Jean-Hugues Royer]

Hi,

In fact  I create a contour widget (contourwidget) to draw the curve 
(with a vtkBezierContourLineInterpolator) and to show the problem I 
trace a straight line (instead of a curve) with two single points 
(begining / end) parallel to the X axis and with Z = 0.

Then I create a vtkSplineFilter (splinefilter) and do a 
splinefilter->Setinput(countourwidget->GetContourRepresentation()->GetContourRepresentationAsPolyData()).

Then I call splinefilter->SetSubdivideToLength() and 
splinefilter->SetLength(D) with desired distance (D) between points and 
finally splinefilter->Update().

Then I get every points by calling 
splinefilter->GetOutput()->GetPoint(n) and compute the distance 
consecutive points: Sqrt( (x2-x1)^2 + (y2-y1)^2 + (z2-z1) ^ 2).

When I do that with a straight line the distance is always different 
than the one I asked, when I do that with a curve (a simple arc) only 
the first and last ~20 points have a different distance.

So far the workaround I found is to call SetLength(D/100) (so I get 100x 
more points than needed) and I manually select the points among them 
which have almost distance D between them, it works but it requires more 
computation and it is not totally accurate.

I don't think it's related but I'm using Activiz, and the straight line 
I use has a total length of 95mm and I ask for distance (D) of 
0.18648mm. (I tried different values of D and I get the same issue)

Regards.

On 10/07/2012 17:52, Jana Sefcikova wrote:
> Hi,
> can I ask you , how did you check whether they are or are not equally 
> distributed ?
> Also what was length of the  curve and distance, in the case when you 
> get good distribution except corner points?
>
> Jana