[vtkusers] Gimbal Lock?

[Robbie Banks]

Perfect.

 

I was rotating 10 degrees at a time, but as you mentioned because the view
up wasn't sorted, it lost the plot when it hit 90. All working now.

 

Thanks

Robbie

 

From: Wes Turner [mailto:wes.turner at kitware.com] 
Sent: Thursday, April 15, 2010 11:13 AM
To: Robbie Banks
Cc: vtkusers at vtk.org
Subject: Re: [vtkusers] Gimbal Lock?

 

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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