<div dir="ltr">No dice. With the examples code, I would get a blank plane uniform plane with the data name 'elevation' as per the SetName() call. However, now, I get no plane, and for coloring all I see (in paraview) is 'solid color' and 'elevation' is no longer present. Which suggests to me something else is perhaps wrong?<div class="gmail_extra"><br clear="all"><div><div dir="ltr"><br style="color:rgb(102,102,102)"></div></div>
<br><div class="gmail_quote">On Tue, Sep 16, 2014 at 2:03 PM, David Gobbi <span dir="ltr"><<a href="mailto:david.gobbi@gmail.com" target="_blank">david.gobbi@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Oops, the second "SetPoint1" should be "SetPoint2".<br>
<div><div><br>
On Tue, Sep 16, 2014 at 2:02 PM, David Gobbi <<a href="mailto:david.gobbi@gmail.com" target="_blank">david.gobbi@gmail.com</a>> wrote:<br>
> The default plane size is 1x1, so you might need this:<br>
><br>
> gridPoints->SetResolution(gridSize, gridSize);<br>
> gridPoints->SetOrigin(0, 0, 0);<br>
> gridPoints->SetPoint1(gridSize, 0, 0);<br>
> gridPoints->SetPoint1(0, gridSize, 0);<br>
><br>
> On Tue, Sep 16, 2014 at 1:49 PM, Chris Marsh <<a href="mailto:chris.marsh@usask.ca" target="_blank">chris.marsh@usask.ca</a>> wrote:<br>
>> Hi David,<br>
>><br>
>> To clarify: I want to take an unstructured grid (x,y) with face data (z) and<br>
>> make it a 2D structured grid. I have connectivity information<br>
>> (triangulation).<br>
>><br>
>> Looking at vtkPlaneSource: looks like it should work/make my life easier<br>
>><br>
>> However, even with the above linked demo with the slight modification, I<br>
>> cannot make this work. This is most likely a PEBKAC as a result of my lack<br>
>> of familiarity with VTK so I appreciate you taking the time to help. The<br>
>> minimum working example is below, based upon this code<br>
>> <a href="http://www.itk.org/Wiki/VTK/Examples/Cxx/PolyData/InterpolateMeshOnGrid" target="_blank">http://www.itk.org/Wiki/VTK/Examples/Cxx/PolyData/InterpolateMeshOnGrid</a><br>
>><br>
>> vtkSmartPointer<vtkPoints> points = vtkSmartPointer<vtkPoints>::New();<br>
>> vtkSmartPointer<vtkFloatArray> data =<br>
>> vtkSmartPointer<vtkFloatArray>::New();<br>
>> data->SetName("elevation");<br>
>><br>
>> unsigned int gridSize = 10;<br>
>> float maxHeight = 5;<br>
>> for ( unsigned int i = 0; i < 100; ++i )<br>
>> {<br>
>> double x = vtkMath::Random(0, gridSize);<br>
>> double y = vtkMath::Random(0, gridSize);<br>
>> double z = vtkMath::Random(0, maxHeight);<br>
>> points->InsertNextPoint ( x, y, 0);<br>
>> data->InsertNextValue(z);<br>
>> }<br>
>><br>
>> // Add the grid points to a polydata object<br>
>> vtkSmartPointer<vtkPolyData> polydata =<br>
>> vtkSmartPointer<vtkPolyData>::New();<br>
>> polydata->SetPoints ( points );<br>
>> polydata->GetPointData()->SetScalars(data);<br>
>><br>
>> // Triangulate the grid points. If you do not have a mesh (points<br>
>> // only), the output will not be interpolated!<br>
>> vtkSmartPointer<vtkDelaunay2D> tri =<br>
>> vtkSmartPointer<vtkDelaunay2D>::New();<br>
>> tri->SetInputData ( polydata );<br>
>> tri->Update();<br>
>><br>
>> // Create a grid of points to interpolate over<br>
>> vtkSmartPointer<vtkPlaneSource> gridPoints =<br>
>> vtkSmartPointer<vtkPlaneSource>::New();<br>
>> gridPoints->SetResolution(gridSize, gridSize);<br>
>> gridPoints->SetOrigin(0, 0, 0);<br>
>><br>
>> // Perform the interpolation<br>
>> vtkSmartPointer<vtkProbeFilter> probeFilter =<br>
>> vtkSmartPointer<vtkProbeFilter>::New();<br>
>> probeFilter->SetSourceConnection(tri->GetOutputPort());<br>
>> probeFilter->SetInputData(gridPoints->GetOutput()); //<br>
>> // Interpolate 'Source' at these points<br>
>> probeFilter->Update();<br>
>><br>
>> vtkSmartPointer<vtkDelaunay2D> gridDelaunay =<br>
>> vtkSmartPointer<vtkDelaunay2D>::New();<br>
>> gridDelaunay->SetInputConnection ( probeFilter->GetOutputPort() );<br>
>><br>
>> vtkSmartPointer<vtkXMLPolyDataWriter> gridWriter =<br>
>> vtkSmartPointer<vtkXMLPolyDataWriter>::New();<br>
>> gridWriter->SetFileName ( "gridSurface.vtp" );<br>
>> gridWriter->SetInputConnection ( gridDelaunay->GetOutputPort() );<br>
>> gridWriter->Write();<br>
>><br>
>><br>
>><br>
>><br>
>> On Tue, Sep 16, 2014 at 12:07 PM, David Gobbi <<a href="mailto:david.gobbi@gmail.com" target="_blank">david.gobbi@gmail.com</a>> wrote:<br>
>>><br>
>>> If you want to create a polydata that is a regular grid, then<br>
>>> use vtkPlaneSource with SetResolution(gridSize, gridSize).<br>
>>><br>
>>> If you want your regular grid to be a vtkImageData, then<br>
>>> use vtkImageGridSource with SetDataExtent(), SetDataSpacing(),<br>
>>> an SetDataOrigin() to create the needed dimensions.<br>
>>><br>
>>> Note that if your point cloud is just points without any connectivity<br>
>>> between the points (i.e. without any cells), then you cannot use<br>
>>> vtkProbeFilter.<br>
>>><br>
>>><br>
>>><br>
>>><br>
>>> On Tue, Sep 16, 2014 at 11:52 AM, Chris Marsh <<a href="mailto:chris.marsh@usask.ca" target="_blank">chris.marsh@usask.ca</a>><br>
>>> wrote:<br>
>>> > Mmh thanks. I think I'll stick with the probe filter.<br>
>>> ><br>
>>> > I've been able to get this example working<br>
>>> > <a href="http://www.itk.org/Wiki/VTK/Examples/Cxx/PolyData/InterpolateMeshOnGrid" target="_blank">http://www.itk.org/Wiki/VTK/Examples/Cxx/PolyData/InterpolateMeshOnGrid</a><br>
>>> > if I have a real-world pt cloud, I'm a bit unclear how I should make the<br>
>>> > grid.<br>
>>> ><br>
>>> > If xll and yll are the lower x and y coordinates of an axis aligned<br>
>>> > bounding<br>
>>> > box<br>
>>> ><br>
>>> > size_t gridSize = 100;<br>
>>> > for ( size_t x = 0; x < gridSize; x++ )<br>
>>> > {<br>
>>> > for ( size_t y = 0; y < gridSize; y++ )<br>
>>> > {<br>
>>> > gridPoints->InsertNextPoint ( x+xll, y+yll, 0);<br>
>>> > }<br>
>>> > }<br>
>>> ><br>
>>> > does not seem to produce any output.<br>
>>> ><br>
>>> > Any suggestions?<br>
>>> ><br>
>>> > On Mon, Sep 15, 2014 at 4:39 PM, David Gobbi <<a href="mailto:david.gobbi@gmail.com" target="_blank">david.gobbi@gmail.com</a>><br>
>>> > wrote:<br>
>>> >><br>
>>> >> Another filter that might work is vtkShepardMethod, which takes<br>
>>> >> unstructured points (e.g. an arbitrary set of samples) as input and<br>
>>> >> produces a vtkImageData as output.<br>
>>> >><br>
>>> >> The difference between vtkProbeFilter and vtkShepardMethod is<br>
>>> >> that the former performs the interpolation based on the connectivity<br>
>>> >> of the points (i.e. based on the cells), while the latter ignores the<br>
>>> >> connectivity and does the interpolation purely based on distance.<br>
>>> >><br>
>>> >> - David<br>
>>> >><br>
>>> >> On Mon, Sep 15, 2014 at 4:23 PM, Chris Marsh <<a href="mailto:chris.marsh@usask.ca" target="_blank">chris.marsh@usask.ca</a>><br>
>>> >> wrote:<br>
>>> >> > Thanks David, this looks perfect.<br>
>>> >> ><br>
>>> >> ><br>
>>> >> > On Mon, Sep 15, 2014 at 4:10 PM, David Gobbi <<a href="mailto:david.gobbi@gmail.com" target="_blank">david.gobbi@gmail.com</a>><br>
>>> >> > wrote:<br>
>>> >> >><br>
>>> >> >> Hi Chris,<br>
>>> >> >><br>
>>> >> >> This sounds like a job for vtkProbeFilter. The probe filter takes<br>
>>> >> >> two<br>
>>> >> >> inputs,<br>
>>> >> >> the "input" and the "source". The idea is that it resamples the<br>
>>> >> >> scalars<br>
>>> >> >> from<br>
>>> >> >> the "source" onto the geometry of the "input". So, in this case,<br>
>>> >> >> the<br>
>>> >> >> "source"<br>
>>> >> >> is your unstructured grid, and the "input" is any vtkImageData that<br>
>>> >> >> has<br>
>>> >> >> the<br>
>>> >> >> origin, spacing, and extent that you want to use for the regridding.<br>
>>> >> >> The<br>
>>> >> >> output of vtkProbeFilter will be an image that has the same geometry<br>
>>> >> >> as<br>
>>> >> >> the input, but that has pixel values that have been interpolated<br>
>>> >> >> from<br>
>>> >> >> your<br>
>>> >> >> unstructured grid. You should be able to find several examples on<br>
>>> >> >> the<br>
>>> >> >> wiki.<br>
>>> >> >><br>
>>> >> >> - David<br>
>>> >> >><br>
>>> >> >><br>
>>> >> >> On Mon, Sep 15, 2014 at 3:59 PM, chrism <<a href="mailto:chris.marsh@usask.ca" target="_blank">chris.marsh@usask.ca</a>><br>
>>> >> >> wrote:<br>
>>> >> >> > Is it possible to (easily) convert an unstructured grid to a<br>
>>> >> >> > structured<br>
>>> >> >> > grid<br>
>>> >> >> > (Image data)?<br>
>>> >> >> ><br>
>>> >> >> > Is unstructured -> polydata -> image data the only way? If so,<br>
>>> >> >> > how<br>
>>> >> >> > example<br>
>>> >> >> ><br>
>>> >> >> ><br>
>>> >> >> > (<a href="http://www.vtk.org/Wiki/VTK/Examples/Cxx/PolyData/DataSetSurfaceFilter" target="_blank">http://www.vtk.org/Wiki/VTK/Examples/Cxx/PolyData/DataSetSurfaceFilter</a><br>
>>> >> >> > ??)<br>
>>> >> >> ><br>
>>> >> >> > Ultimately, the unstructured grid represents a topography, and I<br>
>>> >> >> > am<br>
>>> >> >> > looking<br>
>>> >> >> > to 'rasterize' it for use in a GIS.<br>
>>> >> ><br>
>>> >> ><br>
>>> ><br>
>>> ><br>
>><br>
>><br>
</div></div></blockquote></div><br></div></div>