rock-gazebo should ensure that the spherical coordinates heading is rotated by 90 degrees

[doudou]

In order for Gazebo to use NWU for e.g. GPSes, one need to have a <heading_deg>90</heading_deg> tag in the world. This is more or less a requirement if one wants to use georeferenced coordinates in a Gazebo environment linked to Rock.

So far, the system will misbehave silently if this is not done, I see two possibilities to improve the situation:

• make rock-gazebo, which already preprocesses the world file, auto-add the tag if it is not present. It would leave an existing heading_deg tag alone so that one can force another heading deg.
• make rock-gazebo fail if heading_deg is not set to the expected heading.

[doudou]

@GuilhermePSC @alexfneves this is why the GPS output is not NWU. You need to add <heading_deg>90</heading_deg> to the spherical coordinates block to fix it. I won't do it myself as it needs to be synchronized with the removal of the workaround you implemented.

[alexfneves]

It worked! We added the <heading_deg>90</heading_deg> on the sdf file and removed the task we were using to convert the gps data into xyz in gazebo.

I don't know why, the <world_frame_orientation>NWU</world_frame_orientation> didn't seem to work on gazebo, while <heading_deg>90</heading_deg> did the trick. The sdf documentation actually tell us to use -90 deg with default ENU on the orientation, but the 90 deg that seemed right.