[Rock-dev] RigidBodyState detecting invalid orientations

[Alexander Duda]

On 06/29/2012 05:02 PM, Javier Hidalgo Carrió wrote:
> +1
> Since Orientation is a Eigen::Quaternion we could even use the norm() 
> method.
>
> Javier.
>
> Scalar 
> <http://eigen.tuxfamily.org/dox/classEigen_1_1QuaternionBase.html#a844358c46408e878e60c4026c52eb1e9> 
> norm 	( 	
> 	) 	const|[inline]|
>
> *Returns:*
>     the norm of the quaternion's coefficients 
>
> *See also:*
>     QuaternionBase::squaredNorm()
>     <http://eigen.tuxfamily.org/dox/classEigen_1_1QuaternionBase.html#a8699d72c996ca6cb4673e810fe3a616c>,
>     MatrixBase::norm()
>     <http://eigen.tuxfamily.org/dox/classEigen_1_1MatrixBase.html#a0be1b433c65ce9d92c81a4718daf54e5>
>
>
>
I think you do not gain so much from this functions as you will get a 
scalar which you have to sum anyway. Do you know if there is a function 
which checks if the quaternion is valid?

The proposed code was terrible wrong -- so here is the correction
fabs(ori.w()*ori.w()+ori.x()*ori.x()+ori.y()*ori.y()+ori.z()*ori.z()-1.0) < 
1e-6

Alex
> On 06/29/2012 04:53 PM, Alexander Duda wrote:
>> Hi,
>>
>> the base type samples::RigidBodyState has a function to check if the
>> orientation is valid.
>> At the moment it only checks if the values of the quaternion
>> representing the orientation are different to NaN.
>>
>> I propose that we also add a check that the quaternion is an unit
>> quaternion because otherwise wrongly initialised orientations might lead
>> to strange transformation matrices and vanishing objects in OSG.
>>
>> Any opinions?
>>
>> Alex
>>
>>           static bool isValidValue(base::Orientation const&  ori)
>>           {
>>               return !base::isNaN(ori.w())&&
>>                   !base::isNaN(ori.x())&&
>>                   !base::isNaN(ori.y())&&
>>                   !base::isNaN(ori.z())&&
>>
>> ori.w()*ori.w()+ori.x()*ori.x()+ori.y()*ori.y()+ori.z()*ori.z()-1e6<  1;
>>           }
>>
>
>
> -- 
> Javier Hidalgo Carrió
> ESA - NPI Programme
> Researcher
>
> DFKI Bremen
> Robotics Innovation Center
> Robert-Hooke-Straße 5
> 28359 Bremen, Germany
> http://robotik.dfki-bremen.de
>
> Phone:+49(0)421 17845 6661
> Fax: +49(0)421 17845 4150
>
>
>
> _______________________________________________
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-- 
Dipl.-Ing. Alexander Duda
Unterwasserrobotik

DFKI Bremen
Robotics Innovation Center
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28359 Bremen, Germany

Phone: +49 (0)421 178-456620
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E-Mail: alexander.duda at dfki.de

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