<div class="gmail_quote">On Fri, May 14, 2010 at 1:15 PM, Nicolas Sarrasin <span dir="ltr"><<a href="mailto:nsarrasin@phenix-systems.com">nsarrasin@phenix-systems.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div bgcolor="#ffffff" text="#003333">
<font size="-1"><font face="Tahoma">Ok thanks for your reply.<br></font></font></div></blockquote><div><br>Please keep mails on the list, so others may chime in.<br> </div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div bgcolor="#ffffff" text="#003333"><font size="-1"><font face="Tahoma">
<br>
I'm gonna use </font></font><i><small><font face="Tahoma">vtkPolygonalSurfaceContourLineInterpolator</font></small></i><small><font face="Tahoma">, it satisfied me, for the moment.<br></font></small></div></blockquote>
<div><br>Great.<br> <br></div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><div bgcolor="#ffffff" text="#003333"><small><font face="Tahoma">
<br>
</font></small><div class="im">
<blockquote type="cite"><small><font face="Tahoma">The interpolator
internally traces the shortest path between the two
nodes along vertices of the mesh, so its not as good as a projection
that cuts through the cells, but if your mesh is dense enough the
traced path might be good enough.</font></small></blockquote>
<br>
</div><small>What do you suggest me if my mesh isn't dense enough ? How can i
project the contour on my sphere ?</small><br></div></blockquote><div><br>The path is an approximation of a projection onto the mesh, such that the projected path lies wholly along the vertices of the mesh.<br><br></div>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><div bgcolor="#ffffff" text="#003333">
<small><font face="Tahoma"><br>
Now I encounter a new "problem" in using contour widget. After closing
a contour, everytime I try to modify it by dragging a node, the node
can be move outside the surface (it's still inside the silhouette of
the sphere but it's not lying on any more and approach the screen).<br></font></small></div></blockquote><div><br>This should not happen if you are using a vtkPolygonalSurfacePointPlacer to constrain the nodes and the vtkPolygonalSurfaceContourLineInterpolator to constrain the path. <br>
<br>Please post a minimal, (compiling) example. Also take a look a look at TestDijkstraImageGeodesicPath. The contour and the interpolated path are confined to the surface of the mesh, while you manipulate interactively.<br>
<br>--<br>karthik<br> <br></div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><div bgcolor="#ffffff" text="#003333"><small><font face="Tahoma">
<br>
How can I manage this problem and constrain the position of the node of
the contour during all its lifetime in the visualisation?<br>
<br>
Thanks by advance,<br>
<br>
Nicolas<br>
</font></small><br>
Le 12/05/2010 18:43, Karthik Krishnan a écrit :
<div><div></div><div class="h5"><blockquote type="cite">Yes Nicolas:<br>
<br>
The contour widget uses two sets of classes, which (are generally
independent of each other).<br>
<br>
A subclass of vtkPointPlacer dictates the constraints imposed on the
nodes. <br>
A subclass of vtkContourLIneInterpolator dictates the constraints
imposed on the path in between the nodes. <br>
<br>
In your case, you might want to look at the following combination :<br>
<br>
vtkPolygonalSurfacePointPlacer ->
vtkPolygonalSurfaceContourLineInterpolator<br>
<br>
The interpolator internally traces the shortest path between the two
nodes along vertices of the mesh, so its not as good as a projection
that cuts through the cells, but if your mesh is dense enough the
traced path might be good enough.<br>
<br>
<br>
Something like :<br>
<br>
<br>
vtkContourWidget *contourWidget = vtkContourWidget::New();<br>
contourWidget->SetInteractor(iren);<br>
<br>
vtkOrientedGlyphContourRepresentation *rep = <br>
vtkOrientedGlyphContourRepresentation::SafeDownCast(<br>
contourWidget->GetRepresentation());<br>
<br>
vtkPolygonalSurfacePointPlacer * pointPlacer <br>
= vtkPolygonalSurfacePointPlacer::New();<br>
pointPlacer->AddProp( sphereActor );<br>
rep->SetPointPlacer(pointPlacer);<br>
<br>
vtkPolygonalSurfaceContourLineInterpolator * lineInterpolator <br>
= vtkPolygonalSurfaceContourLineInterpolator::New();<br>
rep->SetLineInterpolator(lineInterpolator);<br>
<br>
iren->Initialize();<br>
contourWidget->EnabledOn();<br>
<br>
<br>
Hope this helps.. Here is a minimal example..<br>
<br>
--<br>
karthik<br>
<br>
<br>
<div class="gmail_quote">On Wed, May 12, 2010 at 7:21 PM, Nicolas
Sarrasin <span dir="ltr"><<a href="mailto:nsarrasin@phenix-systems.com" target="_blank">nsarrasin@phenix-systems.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div bgcolor="#ffffff" text="#003333">Hi all,<br>
<br>
I'm quite new in developping with vtk and I have some questions
concerning vtkContourWidget.<br>
<br>
I built a quick project which uses vtkContourWidget and
vtkPolyDataPointPlacer to display a contour on a sphere.<br>
<br>
When I click on this sphere, there's no problem : the points of the
contour are well positionned on the sphere. But it's not the case for
the spans which are outside or inside the sphere (but not on).<br>
<br>
Is there a way to force the borders of the contour to follow the
surface ?<br>
<br>
A solution would be to project the contour on the sphere but I can find
any documentation about that.<br>
<br>
For more clarity, I post a sample of my code.<br>
<br>
Thanks by advance.<br>
<br>
Nicolas<br>
<br>
code:<br>
<pre> //sphere definition
vtkSphereSource* theSphere = vtkSphereSource::New();
vtkPolyDataMapper * sphereMapper = vtkPolyDataMapper::New();
sphereMapper->SetInput(theSphere->GetOutput());
vtkLODActor* sphereActor = vtkLODActor::New();
sphereActor->SetMapper( sphereMapper);
vtkRenderer *renderer1 = vtkRenderer::New();
renderer1->AddActor(sphereActor);
vtkRenderWindow *renWin = vtkRenderWindow::New();
renWin->AddRenderer(renderer1);
vtkRenderWindowInteractor *rendIter = vtkRenderWindowInteractor::New();
rendIter->SetRenderWindow(renWin);
// Here comes the image actor constrained handle widget stuff.....
vtkContourWidget *widget = vtkContourWidget::New();
widget->SetInteractor(rendIter);
vtkSmartPointer<vtkLinearContourLineInterpolator> contourStyle =
vtkSmartPointer<vtkLinearContourLineInterpolator>::New();
vtkOrientedGlyphContourRepresentation *rep
=vtkOrientedGlyphContourRepresentation::SafeDownCast(
widget->GetRepresentation() );
rep->SetLineInterpolator(contourStyle);
// we define a Placer to force the contour to be on the sphere
vtkPolyDataPointPlacer * spherePlacer = vtkPolyDataPointPlacer::New();
spherePlacer->AddProp(sphereActor);
rep->SetPointPlacer(spherePlacer);
renWin->Render();
rendIter->Initialize();
widget->EnabledOn();
rendIter->Start();/
</pre>
<br>
<div>-- <br>
<br>
</div>
</div>
<br>
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