<div dir="ltr"><div><div><div>Hi Martin,<br><br></div>I haven't looked closely enough at vtkTensors (I don't know if I even knew about it before today) but indeed the ordering output in vtkCellDerivatives for a velocity vector {u,v,w} needs to be [du/dx, du/dy, du/dz, dv/dx, dv/dy, ...] like you have it. I'm not sure when vtkTensors is ordered the way it is.<br><br></div>Cheers,<br></div>Andy<br></div><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Jan 19, 2016 at 5:02 PM, Martin Genet <span dir="ltr"><<a href="mailto:martin.genet@polytechnique.edu" target="_blank">martin.genet@polytechnique.edu</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF">
Thanks Andy.<br>
<br>
I need to clarify something: the Derivatives function of vtkCell
objects returns a derivs vector containing the components of the
gradient of some vector field defined at the cell nodes; the
components are ordered in row (as usually in C, i.e., (0,0), (0,1),
(0,2), (1,0), (1,1), (1,2), (2,0), (2,1), (2,2)). Now in the
CellDerivatives filter the derivs vector is used to fill a
vtkTensors, and then the filter returns the internal vector storing
the data of the vtkTensors. However, the components of the
vtkTensors are ordered in column (as usually in fortran, i.e.,
(0,0), (1,0), (2,0), (0,1), (1,1), (2,1), (0,2), (1,2), (2,2)). Is
it on purpose that the vtkTensors store their data in column and not
in row? Isn't it a little dangerous to mix both storage in the code?
Thanks for the clarification!<span class="HOEnZb"><font color="#888888"><br>
<br>
Martin</font></span><div><div class="h5"><br>
<br>
<div>On 18/01/2016 13:32, Andy Bauer wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">
<div>
<div>
<div>Hi Martin,<br>
<br>
</div>
Thanks for following up on this. I found the merge request
now and will look at this. In general, developers should
request others to do a code review on this. This can be done
via something like "@acbauer please review this" or sending
an email on this VTK list with a link to the merge request.<br>
<br>
</div>
Best,<br>
</div>
Andy<br>
</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Mon, Jan 18, 2016 at 6:23 AM, Martin
Genet <span dir="ltr"><<a href="mailto:martin.genet@polytechnique.edu" target="_blank">martin.genet@polytechnique.edu</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF"> Hi Andy,<br>
<br>
I followed the directions, and submitted a patch (19 days
ago), but haven't heard anything back.<br>
<br>
In GitLab the merge requests counter is at 0, but when I
try to create a new merge request from my commit, it tells
the merge request already exists. Is it being reviewed
somewhere? Thanks!<span><font color="#888888"><br>
<br>
Martin</font></span>
<div>
<div><br>
<br>
<div>On 29/12/2015 13:22, Andy Bauer wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">
<div>
<div>
<div>Hi Martin,<br>
<br>
</div>
This patch makes sense. It would need a test
if you want to get your changes into VTK. The
directions for contributing to VTK are at <a href="https://gitlab.kitware.com/vtk/vtk/blob/master/Documentation/dev/git/develop.md" target="_blank"></a><a href="https://gitlab.kitware.com/vtk/vtk/blob/master/Documentation/dev/git/develop.md" target="_blank">https://gitlab.kitware.com/vtk/vtk/blob/master/Documentation/dev/git/develop.md</a>.<br>
<br>
</div>
Cheers,<br>
</div>
Andy<br>
</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Mon, Dec 28, 2015 at
5:50 PM, Martin Genet <span dir="ltr"><<a href="mailto:martin.genet@polytechnique.edu" target="_blank"></a><a href="mailto:martin.genet@polytechnique.edu" target="_blank">martin.genet@polytechnique.edu</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF"> Thanks
Andy.<br>
<br>
What about simply adding another mode, e.g.
SetTensorModeToComputeGreenLagrangeStrain,
to the vtkCellDerivatives filter? Would the
attached patch make sense?<br>
<br>
Martin<br>
<br>
<div>On 28/12/2015 14:12, Andy Bauer wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">
<div>
<div>
<div>Hi Martin,<br>
<br>
</div>
Changing the name of the
SetTensorModeToComputeStrain method
to something else would break
backward compatibility which is
generally avoided in VTK. Other
options for this include deriving a
class to compute non-linear strain
from vtkCellDerivatives if it shares
enough of the algorithm with the
linearized version or maybe just
creating a new filter.<br>
<br>
</div>
Cheers,<br>
</div>
Andy<br>
</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Sat, Dec 26,
2015 at 4:36 PM, Martin Genet <span dir="ltr"><<a href="mailto:martin.genet@polytechnique.edu" target="_blank"></a><a href="mailto:martin.genet@polytechnique.edu" target="_blank">martin.genet@polytechnique.edu</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Dear VTK
users:<br>
<br>
I realize that the
vtkCellDerivatives filter, when
SetTensorModeToComputeStrain is
activated, returns the symmetric
part of the gradient of the input
vector field, which is the
linearized strain tensor, i.e., not
a proper measure of deformation when
large displacements are involved.
Would that make sense to have two
different modes,
SetTensorModeToComputeLinearizedStrain
or
SetTensorModeToComputeSymmetricGradient,
and SetTensorModeToComputeStrain or
SetTensorModeToComputeGreenLagrangeStrain?
Thanks!<br>
<br>
Martin<br>
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