[vtkusers] Unstructured grid to structured grid?

[Chris Marsh]

Further to this:

Tri bounds xmin:624714 xmax:629904 ymin:5.64502e+06 ymax:5.64877e+06
gridpoints bounds xmin:624714 xmax:629904 ymin:5.64502e+06 ymax:5.64877e+06
gridDelaunay bounds xmin:1 xmax:-1 ymin:1 ymax:-1

It appears the final triangulation of the probed points is the problem

vtkSmartPointer<vtkDelaunay2D> gridDelaunay =
vtkSmartPointer<vtkDelaunay2D>::New();
    gridDelaunay->SetInputConnection ( probeFilter->GetOutputPort() );

    vtkSmartPointer<vtkXMLPolyDataWriter> gridWriter =
 vtkSmartPointer<vtkXMLPolyDataWriter>::New();
    gridWriter->SetFileName ( file_name.c_str());
    gridWriter->SetInputConnection ( gridDelaunay->GetOutputPort() );
    gridWriter->Write();

Is this final triangulation required? Is there a better way of doing this?

Thanks, Chris

On Tue, Sep 16, 2014 at 7:03 PM, Chris Marsh <chris.marsh at usask.ca> wrote:

> Ah I see resolution is just subdivisions.
> http://www.vtk.org/doc/nightly/html/classvtkPlaneSource.html#acd65f04a453ba87b766048f0e7597710
>
> I have also confirmed bbox matches exactly the values that GetBounds()
> reports.
>
> On Tue, Sep 16, 2014 at 6:16 PM, Chris Marsh <chris.marsh at usask.ca> wrote:
>
>> Yes, I was trying to be optimistic :( Good call on the bounds:
>> vtu export: xmin:624714 xmax:629904 ymin:5.64502e+06 ymax:5.64877e+06
>> vtp export: xmin:1 xmax:-1 ymin:1 ymax:-1
>>
>> Presumably the problem. I'm unclear why it is doing this though?
>>
>> vtkSmartPointer<vtkPlaneSource> gridPoints =
>> vtkSmartPointer<vtkPlaneSource>::New();
>>
>> int gridSize = 1000;
>> gridPoints->SetResolution(gridSize, gridSize);
>> gridPoints->SetOrigin(bbox.vertex(0).x(),  bbox.vertex(0).y(), 0);
>> gridPoints->SetPoint1(bbox.vertex(2).x(), bbox.vertex(0).y(), 0);
>> gridPoints->SetPoint2(bbox.vertex(0).x(), bbox.vertex(2).y(), 0);
>> gridPoints->Update();
>>
>> where bbox is a bounding box (2D), index 0 is bottom left, indexing is
>> increasing CCW. So 2 is upper right corner. As far as I can tell this is
>> correct and corresponds to the vtu export numbers I had above.
>>
>> I feel like I perhaps don't understand resolution: I envision it as the
>> size of each cell, however I don't think that is correct is it?
>>
>>
>>
>> On Tue, Sep 16, 2014 at 5:23 PM, David Gobbi <david.gobbi at gmail.com>
>> wrote:
>>
>>> On Tue, Sep 16, 2014 at 4:49 PM, Chris Marsh <chris.marsh at usask.ca>
>>> wrote:
>>>
>>> > The interpolation doesn't look very good, even after increasing the
>>> > resolution.  As well, it is flipped along the y-axis. Image is a
>>> mountain,
>>> > variable is air temp (blue = cold, red = warm).
>>> > See here: http://imgur.com/l1KpcS0
>>>
>>> Honestly, I can't see any correspondence at all between the mountain
>>> and the interpolated data on that plane.  Are you sure the size and
>>> position of the plane matches the size and position of your data?
>>> An easy way to check is to call GetBounds() on both of them and
>>> print out the bounds.  They should match.
>>>
>>> > Secondly: I need to iterate over the rows/cols of this interpolated
>>> grid in
>>> > order to write it to an ArcGIS ascii file. What would be the best way
>>> to do
>>> > this? The fact it is now in a delaunay triangulation somewhat doesn't
>>> help
>>> > (now that I think about it!)
>>>
>>> The interpolated data can be retrieved via GetPointData()->GetScalars(),
>>> but I'm not sure what ordering the vtkPlaneSource uses for its points.
>>> You can print GetPoint(0) and GetPoint(1) to see whether the points
>>> increase in the X direction or Y direction first.
>>>
>>> Also, watch for off-by-one mistakes.  SetResolution(1, 1) gives a plane
>>> with 4 points (the corners).  So if you want a plane with 4x4 points, you
>>> would SetResolution(3, 3).
>>>
>>>  - David
>>>
>>
>>
>
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