[vtkusers] Cylindrical grid

[Hills David A]

Thanks for the reply,

You're right; I was a bit vague in my description of my situation. I'll
try to be a more explicit:
 
I'm writing an analytical model GUI that uses Qt and VTK. Essentially, I
have a bunch of rectangular components/spaces and some analytical
functions that I want to visualize. These functions are parameterized in
terms of position along a line (possibly skewed relative to the
rectangular components) and radial distance from that line (so they're
symmetrical around the axis of the line). I want to visualize these
functions along with the rectangular objects.

I can see how I might go about creating a mesh that nicely fits with the
rectangular components and then just map from my analytical functions
into this rectilinear space and view it that way. However, I'd like to
be able to show the cylindrical nature of the functions and was hoping I
could define my meshes in coordinates aligned with the line and with
annular shaped cells. 

I hope this better explains the situation although it's a bit hard using
only words! I'm a bit new to VTK and data-visualisation in general so
forgive me if I've got the wrong idea about how I should be approaching
these kinds of tasks.

Thanks again for the help. 

Dave 

* Please consider the environment before printing this email.
-----Original Message-----
From: Burlen Loring [mailto:burlen.loring at kitware.com] 
Sent: 06 November 2008 14:37
To: Hills David A
Cc: vtkusers at vtk.org
Subject: Re: [vtkusers] Cylindrical grid

Hi Dave,

I see no one else has answered, probably because this is sort of open 
ended question, we don't know enough about your data to provided a 
succinct answer. At any rate I will try to provide some general info.

Vtk uses Cartesian coordinates for points, so you want to convert 
r,theta,z tuples to x,y,z tuples for each node in your data. If you are 
visualizing a solid or volume that is composed from a collection of 
elements or cells, then you first need to determine which vtk cell types

are needed to represent your volume or solid. That will be a deciding 
factor in which dataset to use. For example vtkStructuredGrid only 
offers vtkQuad or vtkHexahedron cells, such that they can be logically 
arranged on a lattice. If your data isn't arranged in that way or you 
need to mix multiple cell types to represent your geometry then probably

vtkUnstructuredGrid would be the way to go.


Hills David A wrote:
>
> Hi,
>
> I'm interested in visualizing some data in cylindrical coordinates. 
> Can vtk represent this? I've seen some hints that vtkStructuredGrid 
> could be used for this but the class reference for this explicitly 
> states that this is topologically cuboid so I can't see how that would

> work. Is there anything native that could be used in vtk? I saw that 
> someone asked this question here in August but got no replies so I'm 
> not holding out much hope but I thought I'd try again.
>
> Thanks,
>
> Dave
>
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