what map.info.origin.orientation is for?

Question

I am using gmapping to create maps with lasers. I managed to have successful maps but since obstacles in some indoor spaces (like malls etc..) are transparent (such as glass walls and doors etc...), my project is to enhance the mapping by adding a node using sonars and the laser-created-map (and tf data of course to localise the robot in the map) to generate a more general map with the transparent obstacles in it. (the introduction is to let you know why this question and to have some advices regarding what I want to do..)

So, my question is: Are the /map frame axes (X and Y) parallel to the sides of the "rectangular map"? If not, I guess the information about the /map frame orientation is in "map.info.origin.orientation". No? I read in some previous question :(/question/10268/where-am-i-in-the-map/) that "in practice there's no rotation". Is "map.info.origin.orientation" then useless?

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Originally posted by AbuIbra on ROS Answers with karma: 118 on 2014-01-23

Post score: 0

Answer 1

No, it is not useless. Correct implementations should always use the orientation to transform between grid and world coordinates.

It is just that in practice in most cases the orientation is set to 0. If you ignore it, Murphy says that you'll find a map that is rotated.

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Originally posted by dornhege with karma: 31395 on 2014-01-23

This answer was ACCEPTED on the original site

Post score: 1

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Original comments

Comment by AbuIbra on 2014-01-23:
Set to 0? where? Can I set it myself to 0, just to make sure it is 0?

Comment by dornhege on 2014-01-23:
Whoever produces the map must set this. If you set it to something different than in the map originally you are making it unsafe as you're basically changing the map. You can check if it is already 0 to be safe (if you are ignoring orientation).

Comment by AbuIbra on 2014-01-23:
ok thank you

Answer 2

Just in case someone needs to know, in GMapping the "map.info.origin.orientation" is 0 (quat = [0 0 0 1]).

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Originally posted by AbuIbra with karma: 118 on 2014-01-23

This answer was NOT ACCEPTED on the original site

Post score: 1