where are stored obstacles from map?

asked 2014-08-14 03:51:38 -0500

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hello, I want to check if my path is correct on many maps, so i want to know the position of the obstacles. The map is provided by map_server ( a picture in black for obstacles and white for empty spaces).

I Was thinking that these values were stored in the cotmap_ of my global_planner but I have checked costmap_.getCost(i,j) for all the position and everything is empty. ( if i sent a goal to my move_base, my robot avoid the obstacles)

So my question is where are stored obstacles from my map?

thanks

answered 2014-08-14 07:32:55 -0500

GuillaumeB

312 ●16 ●23 ●28

I have solve my problem. As always in my case it was a stupid mistake. The things is :

the funtion getCost(mx,my) don't take meters but cells's coordinate (only positive coordinate).
the most importante in my case, the zero of the world is not always the center of the map (in my case my map was a little bit smaller).

So global_costmap contain obstacles from the map.

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Hi, i have a similar question/problem but for the opposite occupancy, i want to extract the FREE cell coordinates of my map and the use them for navigation. do you happen to have a code snip for the free cell export or if can guide to the right path? Thanks a million.

sobot ( 2015-05-03 14:46:48 -0500 )edit

has I explained if you have a costmap2_d you can use the function getCost(mx,my). This will return you 0 if it's a free cell ( but free cells could have values different than 0 if there are close to an object. --> http://wiki.ros.org/costmap_2d )

GuillaumeB ( 2015-05-03 16:31:04 -0500 )edit

thnx, that part i know. my noob problem is how to index cell coords in the first place, i.e in a vector. are them stored somewhere that can be accessed? and then isolate the FREE cells based on their cost of course. - thanks again for your elaboration.

sobot ( 2015-05-04 03:56:18 -0500 )edit

@sobot "Comment" is not suitable for asking a new question. You should open a new question referring to this thread.

130s ( 2015-05-04 04:28:19 -0500 )edit

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