[ros-users] Filters

Thu Apr 1 20:17:41 UTC 2010

Peshala,
Thanks for the feedback.  You're exactly right.  The wiki xml parsing was
stripping all the colons out of the display.  I have changed it to render as
text and opened a ticket <https://code.ros.org/trac/ros/ticket/2569> for
it.

Tully

On Thu, Apr 1, 2010 at 7:52 AM, Peshala Jayasekara <peshala_24 at yahoo.com>wrote:

> I managed to solve the problem.
> In "http://www.ros.org/wiki/filters/Tutorials/Implementing a simple
> filter" it says that something similar to
> <class name="IncrementFilterInt" type="filtersIncrementFilter<int>"
>             base_class_type="filtersFilterBase<int>"> should be included in
> the plugin_description_file.
>
> However, according to
> http://www.ros.org/wiki/pluginlib/PluginDescriptionFile it should be
> <class name="MyPlugin" type="my_namespace::MyPlugin"
> base_class_type="interface_namespace::PluginInterface">
>
> so the filtersIncrementFilter part should be filters::IncrementFilter and
> filtersFilterBase should be filters::FilterBase
>
> Please correct me if I am wrong.
> Now I can load my plugin inside the node scan_to_scan_filter_chain
>
> Thanks
>
> Peshala
>
> ------------------------------
> *From:* Peshala Jayasekara <peshala_24 at yahoo.com>
>
> *To:* ros-users at code.ros.org
> *Sent:* Thursday, April 1, 2010 18:53:28
>
> *Subject:* Re: [ros-users] Filters
>
> Tully,
>
> Thank you very much for your reply.
>
> I have already added a plugin description file.
> Its contents are as follows:
>
> <class_libraries>
>   <library path="lib/libbackgroundsubtraction">
>     <class name="LaserBackgroundSubtractionFilter"
> type="beginner_tutorials::LaserBackgroundSubtractionFilter"
>             base_class_type="filtersFilterBase<sensor_msgs::LaserScan>">
>       <description>
>         This is a background subtraction filter.
>       </description>
>     </class>
>   </library>
> </class_libraries>
>
> Also, I have edited the manifest file as follows:
>   <depend package="filters"/>
>   <depend package="sensor_msgs"/>
>   <depend package="pluginlib"/>
>   <export><filters plugin="${prefix}/plugin_description_file.xml"/>
>   </export>
>
> and
> PLUGINLIB_REGISTER_CLASS(LaserBackgroundSubtractionFilter,
> beginner_tutorials::LaserBackgroundSubtractionFilter,
> filters::FilterBase<sensor_msgs::LaserScan>)
> in the .cpp file
>
> I am confused with adding the node configuration parameters.
> Because I am running a launch file
> <launch>
> <node pkg="laser_filters" type="scan_to_scan_filter_chain" output="screen"
> name="background_subtraction_filter">
>       <rosparam command="load" file="$(find
> beginner_tutorials)/launch/background_subtraction_filter.yaml" />
> </node>
> </launch>
>
> So when I run the launch file it says
> According to the loaded plugin descriptions the class
> LaserBackgroundSubtractionFilter with base class type
> filters::FilterBase<sensor_msgs::LaserScan> does not exist.
>
> On the other hand, when I tried putting my .h and .cpp files inside
> laser_filters and using laser_filter namespace and editing its CMakeLists
> and laser_filters_plugins I could run the scan_to_scan_filter_chain node
> without problem; however I know this is not the recommended way.
>
> Also, in http://www.ros.org/wiki/pluginlib
> it says PLUGINLIB_DECLARE_CLASS which is not to be found in
> <pluginlib/class_list_macros.h>
>
> Need some advice how I can run scan_to_scan_filter_chain node using my
> libbackground_subtraction_filter.so outside the laser_filters package
>
> Thanks in advance
> Peshala
>
>
> ------------------------------
> *From:* Tully Foote <tfoote at willowgarage.com>
> *To:* ros-users at code.ros.org
> *Sent:* Thursday, April 1, 2010 4:49:23
> *Subject:* Re: [ros-users] Filters
>
> Peshala,
>
> For question 1 you need to add a plugin description file.  See
> http://www.ros.org/wiki/pluginlib  linked from here
> http://www.ros.org/wiki/filters  You will both need to add this file and
> export it in the manifest.
>
> To run it inside the scan_to_scan_filter_chain node you just need to add
> your filter to the nodes configuration parameters.  See 3.2.2 in
> http://www.ros.org/wiki/filters#Steps_to_create_a_filter  There is
> specific documentation on scan_to_scan_filter_chain node at
> http://www.ros.org/wiki/laser_filters
>
> For question 2, filters can be run in any node.  The filters::FilterChain
> class is the recommended way to instantiate filters in code.  However for
> your purposes the scan_to_scan_filter_chain node is likely the easiest.
>
> Tully
>
> On Wed, Mar 31, 2010 at 12:05 AM, Peshala Jayasekara <peshala_24 at yahoo.com
> > wrote:
>
>> Dear Ros-Users,
>>
>> I am thinking of writing a background subtraction filter for my incoming
>> laser data through hokoyo_node.
>>
>> Here are my problems.
>>
>> 1) After going through the examples of laser_filters, I thought I can use
>> scan_to_scan_filter_chain node to run "background_subtraction_filter-which
>> is the one I am writing, inside it. However, it gave an error msg saying
>>
>> According to the loaded plugin descriptions the class
>> LaserBackgroundSubtractionFilter with base class type
>> filters::FilterBase<sensor_msgs::LaserScan> does not exist.
>>
>> Is there a way to run a user's filter inside scan_to_scan_filter_chain
>> node?
>>
>> 2) On the other hand, once you write your own filter according to the
>> "Implementing a simple filter" tutorial how do you run it - what node should
>> it be associated with ?
>>
>> Thank you in advance
>> Peshala
>>
>>
>>
>> ------------------------------
>>  Get your preferred Email name!
>> <http://sg.rd.yahoo.com/aa/mail/domainchoice/mail/signature/*http://mail.promotions.yahoo.com/newdomains/aa/>
>> Now you can @ymail.com and @rocketmail.com.
>>
>> _______________________________________________
>> ros-users mailing list
>> ros-users at code.ros.org
>> https://code.ros.org/mailman/listinfo/ros-users
>>
>>
>
>
> --
> Tully Foote
> Systems Engineer
> Willow Garage, Inc.
> tfoote at willowgarage.com
> (650) 475-2827
>
> ------------------------------
>  Get your preferred Email name!
> <http://sg.rd.yahoo.com/aa/mail/domainchoice/mail/signature/*http://mail.promotions.yahoo.com/newdomains/aa/>
> Now you can @ymail.com and @rocketmail.com.
>
> ------------------------------
>  New Email addresses available on Yahoo!
> <http://sg.rd.yahoo.com/aa/mail/domainchoice/mail/signature/*http://mail.promotions.yahoo.com/newdomains/aa/>
> Get the Email name you've always wanted on the new @ymail and @rocketmail.
> Hurry before someone else does!
>
> _______________________________________________
> ros-users mailing list
> ros-users at code.ros.org
> https://code.ros.org/mailman/listinfo/ros-users
>
>

-- 
Tully Foote
Systems Engineer
Willow Garage, Inc.
tfoote at willowgarage.com
(650) 475-2827
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.ros.org/pipermail/ros-users/attachments/20100401/8e8acac3/attachment-0003.html>