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Height Map output

asked 2018-02-19 11:17:21 -0500

Karim Ahmt gravatar image


Regarding Velodyne lidar obstacles detection. I am using the velodyne_height_map. I was seeking to be able to detect the distance between the sensor and the obstacle and the angle at which the obstacle located. by using the publish command I was able to see the format. if you can help me to be able to understand more of the format of the output data packet.

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answered 2018-02-21 19:23:43 -0500

joq gravatar image

updated 2018-02-21 19:24:46 -0500

The velodyne_obstacles topic is a sensor_msgs/PointCloud2. I believe it's in the frame of reference of the input point cloud, which is normally the device frame, velodyne. The correct frame_id will be in the message header.

The Euclidean distance from any point in that cloud to the device, is the square root of the sum of squares of its x, y, and z coordinates.

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thank you for your answer, but how could I know from the published topic which ones are the x ,y,and z coordinates. as the single data packet is 32 digit no letters .

thank you.

Karim Ahmt gravatar image Karim Ahmt  ( 2018-02-21 19:31:23 -0500 )edit

PointCloud2 is a complex message containing multiple data fields for each point. They "always" include x, y, and z, but may include other data. See:

joq gravatar image joq  ( 2018-02-21 19:35:39 -0500 )edit

thank you very much, appreciate your support

Karim Ahmt gravatar image Karim Ahmt  ( 2018-02-23 12:16:07 -0500 )edit

If this answers your question, please click the check mark above.

joq gravatar image joq  ( 2018-02-23 13:28:19 -0500 )edit

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Asked: 2018-02-19 11:17:21 -0500

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Last updated: Feb 21 '18