[vtkusers] 3 speed questions

[Robert Maynard]

I have just merged the updated contour widget a couple minutes ago. The
changes increase the speed of initializing the widget with large datasets
(100K+ points ), and also increases the active point location speed.


On Mon, Nov 8, 2010 at 3:53 PM, Sebastien Jourdain <
sebastien.jourdain at kitware.com> wrote:

> No, we don't know yet...
> Rob still need to validate its fix with our internal users...
>
> Seb
>
> On Mon, Nov 8, 2010 at 1:48 PM, Jonathan Morra <jonmorra at gmail.com> wrote:
> > 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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>



-- 
Robert Maynard
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