Results get worse compared to commit 116 about cartographer HOT 2 CLOSED

Since #116 there have been algorithmic changes to local SLAM and the default configuration we provide is for a backpack. One could of course bisect to figure out which commit(s) caused the drop in quality, but I'm not sure this is helpful to you. I would think what you need is tuning for the car use case.

I looked into the data you provided, though without the GPS derived odometry. If you think that part is important: Could you record a bag that has the necessary odometry so that I can simply replay it?

It seems the main issue is tuning. For example, I increased the maximum distance to submaps to consider for loop closure to 30 meters. Also, to avoid slipping in one case in the lower right of the map, I increased reliance on the constant velocity model a bit by raising the translation_weight. The 5 cm default resolution is quite high for a car so I changed it to 15 cm.

SPARSE_POSE_GRAPH.constraint_builder.max_constraint_distance = 30.
TRAJECTORY_BUILDER_2D.submaps.resolution = 0.15
TRAJECTORY_BUILDER_2D.ceres_scan_matcher.translation_weight = 3e1

This produces a map very similar to the one you show for #116. I hope this helps you as a starting point. If you have further questions, just let me know.

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Thank you for the quick response. It really looks better now :)
I tryed to record the data, so you dont need to run the nodes, but I failed. I m getting a time syncronisation warning from the Cartographer, while replaying.

[ WARN] [1485363867.747249771, 1485362329.488265818]: W0125 18:04:27.000000 20856 tf_bridge.cc:51] Lookup would require extrapolation into the past. Requested time 1482230642.311152900 but the earliest data is at time 1485362329.634929960, when looking up transform from frame [imu_link] to frame [base_link]

The cartographer is not calculating any results because of this.

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