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Shape recognition and position determination

asked 2017-04-03 16:02:12 -0500

Rwl gravatar image

I'm very new to ROS, and I was looking into the visp_auto_tracker. I need to be able to locate a hole relative to a moving cart, and determine how far away it is. The hole is diamond shaped and can only be orthogonal to the path the cart is on. So, I need to figure out a way to detect if it is lined up with the car, or slightly in front or behind it.

The visp_auto_tracker seemed perfect, but how can you modify the shape it looks for? Or is there a better package out there for my purposes? Thanks

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answered 2017-04-04 06:20:46 -0500

mohsen1989m gravatar image

First try to think about the sensor you are using, are u using a camera? a kinect? a LIDAR. From your question I assume you are using a camera. In this case, you can either approach the problem by using a marker detection algorithm (visp_auto_tracker is a marker detection and not the only one) or a shape detection algorithm (i.e. find_object_2d). I would recommend using a marker detection since it should me more robust, the robustness of the shape detection is highly dependent on features of what u need to detect ... if you want to switch to 3D shape detection, of course in case of using 3D sensors like kinect, tilting LIDAR, velodyne, etc, you can use pcl library and the tools that you find there, having something that works in realtime might be tricky though

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I'm honestly not sure which sensor I want to use if it would be easier to use a Kinect or lidar I'm more than open to doing that. The problem I have is how do you actually change the shape that any given marker detection algorithm looks for?

Rwl gravatar image Rwl  ( 2017-04-04 12:35:53 -0500 )edit

there are different types of marker and each category needs its own detector. Although a marker detection can only detect a marker of its own category, which does not mean that only a specific shape but a specific category. you can usually specify properties of the marker in a xml file in the pkg

mohsen1989m gravatar image mohsen1989m  ( 2017-04-06 04:29:07 -0500 )edit

more about the marker can be found in this thesis

mohsen1989m gravatar image mohsen1989m  ( 2017-04-06 04:29:37 -0500 )edit

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Asked: 2017-04-03 16:02:12 -0500

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Last updated: Apr 04 '17