# Ouster PoseOptimizer guidance needed - preserving SLAM geometry while applying external position authority **URL:** \ **Category:** Software\ **Created:** [September 11, 2026, 6:10am UTC](https://community.ouster.com/t/ouster-poseoptimizer-guidance-needed-preserving-slam-geometry-while-applying-external-position-authority/518 "2026-09-11T06:10:19Z")\ **Posts on this page:** 1\ **Showing post:** 13
**Author:** ![mikehrub](https://avatars.discourse-cdn.com/v4/letter/m/f475e1/32.png) [@mikehrub](https://community.ouster.com/u/mikehrub)\ **Post date:** [September 15, 2026, 7:45am UTC](https://community.ouster.com/t/ouster-poseoptimizer-guidance-needed-preserving-slam-geometry-while-applying-external-position-authority/518/13 "2026-09-15T07:45:03Z")
Thank you again for the detailed explanation of the current ICP failure mode. It is helpful as we plan our next field test. We also posted a separate question about slow rotational drift in longer runs: > [@Correcting slow rotational drift in multi-mile Ouster SLAM runs without smearing geometry](https://community.ouster.com/t/correcting-slow-rotational-drift-in-multi-mile-ouster-slam-runs-without-smearing-geometry/520): > > We are processing multi-mile, vehicle-mounted OS1-071-64U-ASR Rev7 data using firmware 3.2.0, SDK 1.0.1, ACCEL32\_GYRO32\_NMEA, PPS synchronization, and a PPS-aligned PolyNav dual-antenna GNSS/INS. The Ouster SLAM cloud is often internally very clean: pavement, poles, wires, and vegetation remain sharp. However, over a multi-mile run, the cloud can gradually turn or float right/left relative to the road and GNSS/INS trajectory. The apparent attitude difference is commonly about 1-6 degrees, occas… We collect mobile road-corridor data. We are moving to continuous raw recordings with a real stationary period at the start of each processed session, but field work sometimes requires stopping one recording and starting another. Our Ouster is PPS-synchronized, and the PCAP includes a time-aligned GNSS/INS feed with roll, pitch, and yaw. We have tested applying that attitude after SLAM through PoseOptimizer. It can improve leveling, but strong or dense corrections can distort otherwise clean LiDAR geometry. Is there a supported, experimental, or planned way for `ouster-cli source ... slam` to use a PPS-aligned GNSS/INS attitude feed? Could it be useful at the start of a run and, if appropriate, later when LiDAR geometry is weak? We are trying to understand whether the time-aligned attitude already in the recording could support SLAM in an Ouster-recommended way while retaining clean local LiDAR geometry. We understand this may not solve every low-feature ICP failure. If Ouster has a relevant beta or early-access program, we would be interested in participating and can provide repeatable PPS-synchronized PCAP and GNSS/INS examples. --- _[View the full topic](https://community.ouster.com/t/ouster-poseoptimizer-guidance-needed-preserving-slam-geometry-while-applying-external-position-authority/518)._