[Rock-dev] vizkit3d: fixing interpretation of transformer configuration

[Alexander Duda]

On 05/21/2014 12:10 PM, Jakob Schwendner wrote:
> On May 21, 2014 at 10:27 AM Alexander Duda <Alexander.Duda at dfki.de> 
> wrote:
> > Hi,
> >
> > there is a change on master how vizkit3d interprets the transformer
> > configuration. The change is necessary because vizkit3d and
> > driver/transfomer were using different ones:
> >
> > Vizkit3d and driver/transformer are now using the following convention:
> > * All transformations are defined as SOURCE_IN_TARGET frame.
> >
> > Example:
> > static_transform(Eigen::Vector3.new(0.0,0.0,3.0),
> > 
> Eigen::Quaternion.from_euler(Eigen::Vector3.new(Math::PI,0,0),2,1,0),"body" 
>
> > => "world")
> >
> > Meaning:
> > The defined transformation T describes the transformation to convert
> > samples taken in a body coordinate system to a world coordinate system.
> > This is also the reason for its name body_in_world:
> > points_in_body*body_in_world=points_in_world
> >
> > At the same time the transformation T also describes the translation 
> and
> > rotation to convert a world coordinate system to a body coordinate 
> system:
> > body = world*T = world*world_to_body = world*body_in_world
> > world_to_body = body_to_world^(-1) = body_in_world
>
> in all our code we use framea TO frameb as a convention. Changing it 
> to something which uses @in@ is confusing (at least to me) and imho at 
> least requires a discussion before introducing something like that.

This wording is only used for explanation. All our code stays the same. 
But unfortunately the wording framea TO frameb is ambiguous in this context.

Alex

> cheers,
> Jakob


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Dipl.-Ing. Alexander Duda
Unterwasserrobotik
Robotics Innovation Center

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