[ros-users] nodelets for highlevel percetion

[Ulrich Friedrich Klank]

Hi Radu, Hi Tully

thanks for the information.

As I understand it now, it is possible to create the architecture having 
just such a nodelet-manager running on all machines. Now, I just need 
polymorphism in a rosmsg and its done. :)

Cheers,
Uli

Tully Foote wrote:
> Uli,
>
> You are correct that nodelets are basically a thin layer on top of 
> pluginlib.  The goal of nodelets is to facilitate composition of 
> higher level algorithms maintaining the ROS interface for 
> compatability.  And with forthcoming roscpp improvements, messages can 
> be passed intraprocess with zero copies.  And you can have arbitrarily 
> many nodelets in a single process. 
>
> For your specific questions:
>  - Likely you would want to convert each of your plugins into a nodelet. 
>  - As Radu stated, nodelets don't put any restrictions on what you can 
> do inside of them, service calls and servers are definitely fine. 
>  - For "linking" nodelets directly with a node, all you have to do is 
> create a nodelet::NodeletLoader class in the node into which you want 
> to load the nodelets.  Then you can address the node as a nodelet 
> manager, just like a standalone manager. 
>
> Tully 
>
> PS please see my last email about stability.  Keep in mind that 
> nodelets are still in the early developmental stage and will be 
> changing.  http://www.ros.org/wiki/StackVersionPolicy
>
> On Mon, Mar 15, 2010 at 7:41 AM, Radu Bogdan Rusu 
> <rusu at willowgarage.com <mailto:rusu at willowgarage.com>> wrote:
>
>     Hi Uli,
>
>     Think about a nodelet as a C++ class with a ROS interface, sitting
>     on top of pluginlib. There aren't a lot of
>     constraints right now, so you can do pretty much what you want.
>     That being said, the nodelets themselves are just a
>     small part of a bigger architectural change that we are pushing,
>     that also includes roscpp optimizations, etc.
>
>     The nodelet and nodelet_topic_tools are already released under
>     common 1.1, so you can already give them a try.
>
>     We are working on constructing a set of library layers on top of
>     nodelets, including stacks for 3D point cloud
>     processing (PCL), 2D image processing (IPL?), and machine learning
>     (MLL?). PCL has already been released with
>     point_cloud_perception 0.1, while the others are being developed
>     right now. These stacks/packages should provide good
>     examples on how to use the nodelets architecture for 2D/3D
>     processing and learning.
>
>     Cheers,
>     Radu.
>     --
>     | Radu Bogdan Rusu | http://rbrusu.com/
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>
>
>
> -- 
> Tully Foote
> Systems Engineer
> Willow Garage, Inc.
> tfoote at willowgarage.com <mailto:tfoote at willowgarage.com>
> (650) 475-2827
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-- 
Ulrich Klank                        klank at in.tum.de
Technische Universität München | Boltzmannstr 3 | 
85748 Garching bei München  | Germany
www9.in.tum.de/people/klank | Tel: +49 89 289 - 17777