Re: Questions about cameras and PlayerStage sensors

On Friday 01 July 2005 14:48, Artem Orlov wrote:
> On 7/1/05, Peter Soetens <[email protected]> wrote:
> > We do not use Orocos directly to consume video streams. External
> > libraries interprete the stream data and through a custom Sensor
> > Component, provide it in a Control Kernel usable data structure, which is
> > then used by the Controller or Generator of your feedback loop. We have
> > thus not yet written 'fat' components which can handle transparent
> > interoperation with other software libraries, although the Orocos
> > infrastructure probably needs no adaptation to accomodate such
> > components.
>
> I see but there are several packages that implement interfaces to
> device drivers such as Comedi, CANPie, ParallelPort and so on. May be
> it would be great to include drivers for v4l and bttv for example?
>
> Is there any available sample of managing video stream through a
> Sensor Component?

Do you want the whole stream to be passed on to all other components, or 
detect features in the component and pass these on to other components ? 
Orocos is not 'optimized' for streaming large data sets between components, 
but optimized for creating hard realtime control loops and realtime state 
machines. 

That said, the thing that matches your situation the closest is our CANPie 
controller. It is an independent (of the ControlKernel) periodic Orocos task 
which polls for new CAN messages and sends them to special classes which 
convert them to Encoder, DigitalInput etc objects. _then_ our sensor 
component queries these objects for the latest position etc. You'll thus need 
a task which reads out the camera frames, converts the frames to some usefull 
features and integrate it with a (new) 'CameraSensor' component which 
introduces the results in the controller's data flow, allowing a Generator 
and Controller to handle the data.

Peter
-- 
K.U.Leuven, Mechanical Engineering, Robotics Research Group
<http://www.orocos.org> Tel: +32 16 322772