Interface to get pointcloud from SDF

[MA-Wenhui]

Desired behavior

Need an interface to get the world's all collisions and generate the 3d map(pointcloud).

Alternatives considered

I tried to parse sdf file to extract dae/stl/geometry, but it was too complicated since the sdf structures vary.

Implementation suggestion

There is a RayQuery based solution for gazebo-classic:

https://github.com/[arshadlab/gazebo_map_creator](https://github.com/arshadlab/gazebo_map_creator)

I didn't find the equivalent class for this usage in gz harmonic.

Additional context

[arjo129]

I don't know if this should be a core part of gazebo. The buoyancy plugin for instance takes the collision mesh and iterates through the individual meshes.

It would be better to expose an easy to use RayQuery API since this is something that is relatively fundamental to a lot of robotics software.

For your use case of exporting a map I could totally see a way of hacking together a 2d lidar sensor and setting its pose.