[vtkusers] 3 speed questions

[Jonathan Morra]

Is there anything I can do to speed up the Render time?

On Mon, Nov 8, 2010 at 8:13 PM, Karthik Krishnan <
karthik.krishnan at kitware.com> wrote:

> On Tue, Nov 9, 2010 at 2:54 AM, Jonathan Morra <jonmorra at gmail.com> wrote:
> > More information that I've found about the first issue I reported.  I've
> > been narrowing down the issue, and the issue appears to be with
> > vtkImageViewer2.SetSlice(int slice).  This method is very slow when I'm
> > rendering a vtkPolyData that represents a mesh (whether it's cut or not
> is
> > actually irrelevant)
>
> Contrary to what you assume, It is relevant. The SetSlice method
> internally invokes render, so as to update the display in response to
> changes. A "Render" implies that everything displayed on this
> renderwindow is re-rendered. This includes the rendering the polydata.
> If uncut, it can be slow depending on the number of cells. If cut, it
> can take time to update the cutter, since the cut-function (plane) has
> been translated.
>
> > and fast when I'm rendering either nothing or a
> > vtkPolyData that represents a stack of 2D contours.  Does this help at
> all?
>
> Indeed, as mentioned above, there is no cutting to perform here.
> Rendering a bunch of 2D contours is probably faster than rendering
> your entire mesh.
>
> >
> > On Mon, Nov 8, 2010 at 10:26 AM, 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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