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Sick LMS100 small object filters

asked 2012-02-22 13:16:49 -0600

rplankenhorn gravatar image

I am interfacing with a Sick LMS100 laser scanner and I am having problems filtering small objects (such as grass clippings). Are there any tools built into ROS that I could use to filter these objects out easily? If not, what would be the best method for filtering the objects out of the scans?

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answered 2012-02-23 02:51:23 -0600

DimitriProsser gravatar image

updated 2012-02-23 04:12:06 -0600

I've had some success doing this by using PointCloud Library's built-in functions, namely Statistical Outlier Removal. It really depends where the majority of your points lie. If there's a lot of grass, this won't work as well. If the grass is sparse, this method could definitely improve your performance. Radial Outlier Removal might also work.

EDIT:

In order to get a ROS sensor_msgs/PointCloud2 to a pcl cloud, use the following code:

sensor_msgs::PointCloud2 cloud_in;
pcl::PointCloud<pcl::PointXYZ>::Ptr cloud(new pcl::PointCloud<pcl::PointXYZ>);
pcl::fromROSMsg(cloud_in, *cloud);

The cloud variable will now contain a pcl cloud that you can use with the PCL built-in functions.

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This looks like it could work. How do you suggest I implement it? I looked at the PCL page for ROS and the functions to convert from an ROS PointCloud to a PCL PointCloud and back are deprecated. Am I missing something?

rplankenhorn gravatar imagerplankenhorn ( 2012-02-23 03:58:29 -0600 )edit

Use the fuction pcl::fromROSMsg(). The docs might be misleading. This function is not deprecated. The fuction point_cloud::fromMsg() is, but not pcl::fromROSMsg().

DimitriProsser gravatar imageDimitriProsser ( 2012-02-23 04:10:04 -0600 )edit

Thanks again. If the fromMsg is deprecated, how do I convert the pcl::PointCloud back to a PointCloud2?

rplankenhorn gravatar imagerplankenhorn ( 2012-02-23 08:57:11 -0600 )edit

pcl::toROSMsg() does the opposite of pcl::fromROSMsg()

DimitriProsser gravatar imageDimitriProsser ( 2012-02-23 09:06:35 -0600 )edit
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answered 2012-02-22 15:06:37 -0600

joq gravatar image

updated 2012-02-23 04:02:07 -0600

I've never found a solution to that problem.

The grass stops the laser, it gives a return, it looks like a solid object.

EDIT:

Thanks for the clarification. We have used obstacle grids to filter out intermittent noise with fair success.

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I know that if the grass isn't cut it will look like a wall. I am talking about if the area has been freshly mowed and also on a windy day, the grass clippings are flying around in front of the laser. They appear as random small objects.

rplankenhorn gravatar imagerplankenhorn ( 2012-02-23 02:23:29 -0600 )edit

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Asked: 2012-02-22 13:16:49 -0600

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Last updated: Feb 23 '12