[Paraview] [EXTERNAL] Coordinate system transformation

[Manu V G]

Thanks for your quick reply.
Sorry, I was not very clear. I will try to explain clearly here.

> Maybe somebody else understands better, but I am totally confused by what
you are asking. It sounds like you have an original coordinate system x,y,z
and a new coordinate system x1,y1,z1.

I don't have the new coordinate system (x1,y1,z1) loaded in paraview. I
compute the origin and unit vectors of new coordinate system that I need to
create  in paraview using the programmable filter.

> Then you have a velocity vector u,v,w defined in the original coordinate
system (x,y,z) that you want to transform to the new coordinate system
(x1,y1,z1). This should be straightforward in either Calculator or Python
Calculator or Programmable Filter. In fact, it sounds like you are already
doing that.

Yes. I multiple the velocity vector in (x,y,z) system at all points by
transformation matrix. Hence, a new vector is created in (x,y,z) coordinate
system.

> When you say, “however, those velocities correspond to (x1,y1,z1)
coordinate system,” I assume that means that you have already done this
transformation. What do you mean by “associate these… velocities to a new
coordinate system”? You just have associated them with the new coordinate
system.

I meant the new vector created is associated with (x1,y1,z1) coordinate
system. Now, I want to create the new coordinate system (x1,y1,z1) and
associate the new vector to it. If I create a slice normal to 'y' direction
in paraview, I want it to create a slice normal to 'y1' in new coordinate
system.

I hope I am clear?..

Thanks and regards
Manu




>
> From: ParaView <paraview-bounces at paraview.org> on behalf of Manu V G <
manu.gvm at gmail.com>
> Date: Thursday, April 21, 2016 at 11:28 AM
> To: "paraview at paraview.org" <paraview at paraview.org>
> Subject: [EXTERNAL] [Paraview] Coordinate system transformation
>
>
>
> Hello everyone!
>
> Is it possible to create new local coordinate system (x1,y1,z1) and
compute velocities in that (in short coordinate transformation) from the
original system (x,y,z)? Google search did not help me much. And
'Transform' filter do not transform velocities to the new coordinate system
(is a geometrical transformation).
>
> Problem in detail :
>
> I read a 3D velocity field in Paraview and compute orthogonal
eigenvectors (x1,y1,z1) at a certain point 'O1' using 'Programmable
Filter'. These eigenvectors (x1,y1,z1) act as basis for the new coordinate
system with origin 'O1'. I am trying and just want to visualize velocity in
plane z1=0. For this, I need to transform velocity field from original
system to new coordinate system (x1,y1,z1). And I am trying solve it in the
following way. Maybe there is simple way to do it Paraview.
>
> From eigenvectors, I can specify the plane (z1=0) by using a 'Slice'
filter. The velocities in that plane correspond to the global velocity
(u,v,w) in (x,y,z) coordinate system. Then, I use transformation matrix to
compute new velocity vector (u1,v1,w1) using 'Calculator' or 'Python
Calculation'. However, those velocities correspond to (x1,y1,z1) coordinate
system. So, is there a way to associate these newly computed velocities to
a new coordinate system and plot them?
>
> Or is there a different way to do it Paraview?
>
>
>
> I would be very thankful for your suggestions and inputs.
>
>
>
> Thanks in advance, yours
>
> --
>
> Manu V Goudar
>
> Lab of Aero & Hydrodynamics,
>
> Delft University of Technology
>
> Delft, The Netherlands
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