sometimes not trigger loop under the same params and dataset

[narutojxl]

Hi @ziv-lin , i use rosbag_loop.launch and don't modify any param in performance_precision.yaml , play with loop_hku_zym.bag. I run the demo 5 times, and i found sometimes it doesn't trigger loop, but sometimes it can. Did you meet this ? Here is This is the result of a experiment not loop.

[ziv-lin]

This is because I add some randomness during the alignment of the map. For realtime consideration, we randomly drop some of the matchings during ICP of map alignment, this might cause the performance not the alway the same of each launching. Once the maps can not alignment well, we treat the loop detect by 2D-histogram as false positive.

[ziv-lin]

For disable such randomness, you can modify the value in performance_precision.yaml loop_closure/scene_alignment_maximum_residual_block: 3000 from 3000 to an extrmely high value (like 999999).

In addition, you can also fine-tune the value loop_closure/map_alignment_inlier_threshold: 0.2 to a larger value to accept the loop.

[narutojxl]

@ziv-lin, thanks a lot :)