[vtkusers] 3D Visualization of Map Data

[Ron Chapman]

Malcolm,
 
Thanks for your help, once I figured out some basic vtk'isms your
suggestion worked well, albeit roads are sometimes elevated, and/or
disappear through my surface (see the below pipeline).  Now I need to
figure out how to split my road (line segments) into polylines that
intersect with my 2D mesh so that the probing produces better results. 
Does anyone have some hints on how to do this?  I was naively thinking
of the following:
 
create an empty 2d polydata set -> call this NEW
for each 2d line segment in my  2d polydata
    for each line in 3d mesh
        if intersection
            create new line segment
            add new line segment to NEW
 
Then use NEW with the pipeline below insead of Shape2D:
 
// get the evalation scalars
 
 float bounds[6];
 Mesh3D->GetBounds(bounds);
 vtkElevationFilter *Elevation = vtkElevationFilter::New();
 Elevation->SetInput(Mesh3D);
 Elevation->SetLowPoint(0,0,bounds[4]);
 Elevation->SetHighPoint(0,0,bounds[5]);
 Elevation->SetScalarRange(bounds[4], bounds[5]);
 Elevation->Update();
 
  // convert our 3d mesh to 2d
 
 vtkTransform *Transform = vtkTransform::New();
 Transform->Scale(1.0,1.0,0.0);
 
 vtkTransformPolyDataFilter *transFilter =
vtkTransformPolyDataFilter::New();
 transFilter->SetInput((vtkPolyData *) Elevation->GetOutput());
 transFilter->SetTransform(Transform);
 transFilter->Update();
 
 // probe 2d mesh with shape data
 
 vtkProbeFilter *Probe = vtkProbeFilter::New();
 Probe->SetInput(Shape2D);
 Probe->SetSource(transFilter->GetOutput());
 Probe->Update();
 
 // apply the sampled elevation to the overlay
 
 vtkWarpScalar *Warp = vtkWarpScalar::New();
 Warp->SetInput(Probe->GetPolyDataOutput());
 Warp->SetScaleFactor(1.0);
 Warp->Update();

Ron
 
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