[vtkusers] 3 speed questions

[Jonathan Morra]

Thanks for the update, I'm excited to test it out and see if it works for
me.

On Mon, Nov 8, 2010 at 1:04 PM, Robert Maynard
<robert.maynard at kitware.com>wrote:

> 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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