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# Position of objects and joints

Hi all, I have a very basic question. When creating objects where is the measuring point on the object use I am not sure from where the pose is measured from the object. Second problem is with joints. I just need to ask if someone can help me with where to measure from for objects and joints.

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## 1 Answer

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The origin of an object depends on how it was created, and is a matter only of convention. The origin information should be encoded in the sdf. One easy way you can test an object's origin is by adjusting its pose in gazebo in the left hand info pane. For example set Z to 0 and see if it goes about halfway into the ground plane. If so you can probably guess that the Z origin is in the Z center of the object.

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## Comments

I have asked this question because I need to connect different objects through joints. So when I try to place two objects close together, they don't align so I just wanted to know from which point of the object we measure its pose. The center of gravity of the object using simple objects like boxes.

( 2012-11-29 13:57:31 -0600 )edit

Boxes created in gazebo have their origin in their geometric center.

( 2012-11-29 14:58:15 -0600 )edit

Thanks this will help. The problem was that I need to place joints and I need to find out the exact position of the joints.

( 2012-11-30 07:52:26 -0600 )edit

@mfahad Great. If you feel like this answer was correct, could you please click the check-mark just below the vote arrows to indicate that.

( 2012-11-30 10:08:02 -0600 )edit

Thanks. After this semester is over I will like and try to do a small how to manual to model such small things. If you can point me to where I can get data on the different shapes and joints that would be great because I spent a lot of time on it and hope no body else has to.

( 2012-11-30 18:09:32 -0600 )edit

## Stats

Asked: 2012-11-29 11:34:49 -0600

Seen: 781 times

Last updated: Nov 29 '12