[vtkusers] 3 speed questions

[Jonathan Morra]

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) and fast when I'm rendering either nothing or a
vtkPolyData that represents a stack of 2D contours.  Does this help at all?

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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