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ANYbotics / grid_map

Universal grid map library for mobile robotic mapping
BSD 3-Clause "New" or "Revised" License
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transform grid_map frames #170

Closed erichahn closed 2 years ago

erichahn commented 6 years ago

Is it possible to transform grid_map frames from say base_link to odom on a mobile robot platform? I understand how to set a new position, but setting any concept of orientation about the center of the grid appears to not be possible.

When trying to simply do the transform on a grid_map_msg using tfListener the code refuses to compile. Guessing it's not supported as it's a custom type without support.

Thoughts on transforming between frames for either the grid_map or grid_map_msg?

erichahn commented 6 years ago

I have a pointcloud with frame base_link. When I create an intensity image of the point cloud, and then create a grid_map from the image, I get the tf from base_link to odom. I then apply the transform to the grid_map. The translation works properly, but the orientation is not correct at all.

Secondly, if I then try and create an occupancy grid from the grid_map the position transformation is retained, but not the z height. It defaults to 0.

erichahn commented 6 years ago

Between forcing the pose orientation to remain fixed at 0, be set to the transform between frames, or manually adjust roll, pitch, and yaw using dynamic_reconfigure and converting back to a quaternion it seems like the pose orientation in the messages is not used at all. Is this expected?

martinakos commented 2 years ago

I'm finding the same issue. It seems the pose orientation in the GridMapInfo field in grid_map_msgs/GridMap.msg message is not used. Is this a bug?

maximilianwulf commented 2 years ago

Does https://github.com/ANYbotics/grid_map/blob/master/grid_map_core/include/grid_map_core/GridMap.hpp#L324 help you ?

martinakos commented 2 years ago

I need to transform the gridmap out of plane, as my world frame is set by a VIO system and may not be axis aligned with the floor. I solved the problem by creating a moving tf frame for where I want my gridmap in the world and using that one as frame_id then setting the pose to zero.

maximilianwulf commented 2 years ago

Thanks, then this issue can be closed?

martinakos commented 2 years ago

Yes, it can be closed. Thanks.

martinakos commented 2 years ago

I have a problem with the separate moving tf frame solution. I first broadcast a moving tf frame for the elevation map. Then I publish the GridMap using the frame_id of my moving frame. Then I publish some other marker information that is synchronised with the elevation map, but that I can publish on the world frame. This keeps on repeating as new pointclouds from a camera arrive. In Rviz I always see the elevation map with a delay (one update behind) with respect to the other marker information despite both being published at the same time, with same timestamp. From what I could find out the tf system always has a bit of delay. " The delay comes from the fact that tf needs to receive transformations from different broadcasters in the system." https://wiki.ros.org/tf/Troubleshooting#Checking_the_Timestamp So this can explain why I always see the elevation map behind to the corresponding markers.

I guess this is a feature request, but would it be possible to make the Rviz GridMap plug-in to use the GridMap message Pose so that I could use the world frame? Then I wouldn't have a delay between elevation map and the other related markers as I don't have to wait for the tf system.

martinakos commented 2 years ago

Shall I repost my last message as a new feature request issue?