[vtkusers] Unstructured grid to structured grid?

[Chris Marsh]

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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