[vtkusers] how to read UNSTRUCTURED_GRID?

[이정규]

Hi David,

Thank you for your reply and the suggestion, however the file I'm working on
is so-called a legacy VTK file that does not have the newer XML structure.
But from the wiki page that you suggested, I found more information.

Structured Grid

Regular topology and irregular geometry. That is, every point has a left,
right, up, down, front, back neighbor. The points, however, do not lie on a
grid! You must explicitly indicate the coordinates of each point.

This data structure is common in finite difference analysis.


This information gives me food for thought, but is not clear enough that
which goes which.

For example, if I have

x1,y2,z3,x2,y2,z3,x3,y3,z3,x4,y4,z4,x5,y5,z5,x6,y6,z6,x7,y7,z7,x8,y8,z8

I guess it would be something like

(x1,y1,z1),(x2,y2,z2),(x3,y3,z3),(x4,y4,z4)

for the first face.. but what about the next face?? If it have to share some
points(maybe 2, if it have to) with the first face, what would it be like?

Also, if it indeed share some points with its neighboring grids, how many
grid should I expect from n points?


Truly yours,

--

Jeonggyu Lee

On Mon, Mar 15, 2010 at 10:22 AM, David Doria
<daviddoria+vtk at gmail.com<daviddoria%2Bvtk at gmail.com>
> wrote:

> On Mon, Mar 15, 2010 at 11:19 AM, 이정규 <glazex2 at naver.com> wrote:
>
>> Hi all,
>>
>> I am trying to parse a .VTK file with UNSTRUCTURED_GRID but this just have
>> data of points.
>> I've looked for more information for this but all I found is
>>
>> The Visualization Toolkit supports five different dataset formats:
>>> structured points, structured grid, rectilinear
>>
>> grid, unstructured grid, and polygonal data. Data with implicit topology
>>> (structured data such as vtkImageData and
>>
>> vtkStructuredGrid) are ordered with x increasing fastest, then y, then z.
>>> These formats are as follows.
>>
>>
>> So I guess somehow I have to infer the topology from these points. I've
>> tried Paraview and it renders it as a set of rectangles(I've tired to render
>> surface with wireframes and so on)..
>> I see some hint there that points are ordered with x-ascending order, but
>> how the index is consists up is not mentioned in any documents.....
>> Anybody done this before? or have more information for this?
>>
>> PS : If you are someone at Kitware, would you please, please direct me to
>> the right information?????
>>
>> --
>> Jeonggyu Lee
>>
>
> Do you have an existing .vtk file that you need to read? If not, I would
> suggest using the XML .vtu format - then you can use:
>
> http://www.vtk.org/Wiki/VTK/Examples/IO/ReadUnstructuredGrid
>
> Thanks,
>
> David
>
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