[vtkusers] Gimbal Lock?

[Wes Turner]

Hey Robbie,

In general we try to keep cc'ing the conversation to the list.  This both
allows for other users to find an answer in the archives and gives you
access to more brains.

You are probably doing something like;

camera->Elevation(90);

After which Elevation no longer works because it rotates around the cross
product of the ViewUp and DirectionOfProjection vectors and you just made
them colinear.  if instead you do:

camera->Elevation(45);
camera->OrtogonalizeViewUp()
camera->Elevation(45);
camera->OrtogonalizeViewUp()

Everything should continue to work.

On Thu, Apr 15, 2010 at 1:18 PM, Robbie Banks <robbie.banks at gmail.com>wrote:

>  Hi Wes,
>
>
>
> I think I understand what you mean, but could you provide a simple example?
>
>
>
> R
>
>
>
> *From:* Wes Turner [mailto:wes.turner at kitware.com]
> *Sent:* Thursday, April 15, 2010 6:27 AM
> *To:* Robbie Banks
> *Cc:* David Doria; vtkusers at vtk.org
> *Subject:* Re: [vtkusers] Gimbal Lock?
>
>
>
> What you are most likely running into is that the view up vector and the
> view direction vector are becoming the same.  To reach 90 degrees, do it in
> two stages and regenerate the view up vector after each stage.
>
> - Wes
>
> On Wed, Apr 14, 2010 at 7:56 PM, Robbie Banks <robbie.banks at gmail.com>
> wrote:
>
> I’m just wondering if there is a gimbal lock issue with the vtkCamera on
> Elevation(double)??
>
>
>
> I have a 3D object which I am rotating using Elevation(), Azimuth() and
> Roll() to incrementally rotate using directional push buttons. This works
> fine for the Azimuth and Roll, but seems to lock on the Elevation when it
> hits 90 degrees.
>
>
>
> Is this a known problem?
>
>
>
> Robbie
>
>
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> --
> Wesley D. Turner, Ph.D.
> Kitware, Inc.
> Technical Leader
> 28 Corporate Drive
> Clifton Park, NY 12065-8662
> Phone: 518-881-4920
>



-- 
Wesley D. Turner, Ph.D.
Kitware, Inc.
Technical Leader
28 Corporate Drive
Clifton Park, NY 12065-8662
Phone: 518-881-4920
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