[vtkusers] 3 speed questions

[Jonathan Morra]

Thanks for this update, do you guys have any idea when this might be merged?


On Mon, Nov 8, 2010 at 10:46 AM, Sebastien Jourdain <
sebastien.jourdain at kitware.com> wrote:

> Hi Jonathan,
>
> Rob is currently working on vtkContourWidget to make it much faster.
> Right now, its work is not merged to master yet but it's available on
> the git stage of VTK...
>
> Seb
>
>
> On Mon, Nov 8, 2010 at 1:26 PM, Jonathan Morra <jonmorra at gmail.com> wrote:
> > Thanks for your response.  It turns out on my machine that that
> > initialization is too slow.  What's happening is the following
> > 1.  The user click indicating that they want to try a contour
> > 2.  A new vtkContourWidget is made with the dijkstra interpolator.
> > 3.  The contour widget is initialized as I described above with just two
> > points.  Adding that second point is where the slowdown occurs.
> > As far as point 2, I am initializing a contour widget with the output of
> > vtkCutter, but I am subsampling when I do that (I take 7% of the points),
> so
> > I only have a handful of control points.  Is there a way to frontload the
> > load time so I only have to do it once as opposed to every time a user
> wants
> > to draw a contour?  That is simply too slow for my application.
> > Also do you have any idea why rendering the meshes is slow?  Could it be
> > related to the point order, or is is something else?
> > On Sat, Nov 6, 2010 at 8:54 AM, Karthik Krishnan
> > <karthik.krishnan at kitware.com> wrote:
> >>
> >> On Tue, Nov 2, 2010 at 6:31 AM, Jonathan Morra <jonmorra at gmail.com>
> wrote:
> >> > on vtkDijkstraImageContourLineInterpolator and am able to successfully
> >> > create the contour widget with live wire interpolation. However, when
> I
> >> > first initialize the contour with the following code it is very slow
> >> >     // For now, we're just initializing the data with
> >> >     // the point that was clicked
> >> >     vtkPoints points = new vtkPoints();
> >> >
> >> >     // The initial data MUST be at least a "line"
> >> >     // by giving the same point twice we are effictively creating a
> zero
> >> >     // length line
> >> >     points.InsertNextPoint(lastContourControlPoint);
> >> >     points.InsertNextPoint(lastContourControlPoint);
> >> >     vtkPolyData initialData = new vtkPolyData();
> >> >     initialData.SetPoints(points);
> >> >     contourWidget.Initialize(initialData, 0);
> >> > The line that is slow is the last line.  The weird part is that if I
> do
> >> > not
> >> > use live wire, and just use the default Bezier curve interpolation the
> >> > initialization is instant.
> >>
> >> Yes. There are 2 issues here.
> >>
> >> 1. The dijkstra interpolator is a bit slow to start with, since during
> >> the time of initialization, it builds the adjacency information. But
> >> that's not a big deal when you are drawing on an image. The very first
> >> line segment placement is a bit slow (~3 seconds). After that its fast
> >> and interactive.
> >>
> >> 2. The real issue, I think, here is the fact that you are initializing
> >> the contour with the contour with lots of control points. How many of
> >> them are there ? As I understand, you are generating these control
> >> points from the output of vtkCutter ? Perhaps you want to sample the
> >> input polyline and then feed those sample points as the control
> >> points.
> >>
> >> Thanks
> >> --
> >> karthik
> >
> >
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