Attention: Answers.ros.org is deprecated as of August the 11th, 2023. Please visit robotics.stackexchange.com to ask a new question. This site will remain online in read-only mode during the transition and into the foreseeable future. Selected questions and answers have been migrated, and redirects have been put in place to direct users to the corresponding questions on Robotics Stack Exchange. Additional details are available here.

costmap_2d_ros,costmap values problem

asked 2015-03-22 07:36:06 -0500

babaksn
15 ●5 ●6 ●9

hi. i have created a costmap_2d::Costmap2DROS object , but it's values is only between 0 and 100.
when i visualized the 0 values on the rviz it shows the spaces that the robot doesnt have any conflit with obstacles which seems to be correct.
it doesnt have for example 255 values ( NO_INFORMATION ) while my /map topic has -1 (unknown space) values and also rviz shows the unknown spaces correctly from /map topic.
i am using hector slam for map building.
thanks.

edit retag flag offensive close merge delete

add a comment

1 Answer

Sort by » oldest newest most voted

answered 2015-03-22 11:45:06 -0500

paulbovbel

4518 ●12 ●49 ●80 http://www.bovbel.com/

255 is the unsigned equivalent of -1. The OccupancyGrid message ( http://docs.ros.org/indigo/api/nav_ms... ) stores values as signed 8 bit ints - int8, while the Costmap2D object uses the char type internally (equivalent to unsigned 8 bit ints - uint8).

edit flag offensive delete link

Comments

in nav_msgs/OccupancyGrid Message ( the link you have given ) it says that The map data, in row-major order, starting with (0,0). Occupancy probabilities are in the range [0,100]. Unknown is -1. but in my message , there is no any -1 value while my /map topic has -1 values.

babaksn ( 2015-03-22 12:34:30 -0500 )edit

I'm not 100% on what you mean by 'my message', however, if you set a grid inside of Costmap2D, which is represented as a member of an array of chars, to 255, it will show up as -1 in the outgoing message.

paulbovbel ( 2015-03-31 17:02:59 -0500 )edit

add a comment

Question Tools

1 follower

Stats

Asked: 2015-03-22 07:36:06 -0500

Seen: 547 times

Last updated: Mar 22 '15

costmap_2d_ros,costmap values problem edit

1 Answer

Comments

Question Tools

Stats

Related questions

costmap_2d_ros,costmap values problem