The SLAM seems shaky.

Issue description

There is drift inside a building, even after using proper loop closure and scanning practices. Data capture was normal, no lagging or missing panorama locations captured. However after processing the data the Point cloud and panoramas appear off.

Processed Dataset Quality Map:

Dataset Rec Quality Map:

Root cause

The bolts on the NavVis VLX were not fully tightened after unfolding the scanner. The technician was not tightening the bolt until the torque wrench clicked. The loose assembly of the scanner will essentially ruin the Dataset captured as there is no way to recover the data besides processing with top velodyne data separate from the bottom Velodyne's data (not recommended). The loose bolts causes a miscalibration of the sensors from the top scanner to the front scanner and so the accuracy of the data created is flawed as a result.

Troubleshooting procedure

1. Perform a test scan, preferably with 2 levels. Tighten the scanner bolts after unfolding the device until they hear the torque wrench click. Process the data and review using on-prem processing as you will need the datasets_proc files. Look either in the Maps folder or in the Internal folder for the x-ray views like the above screen shots show. If dataset looks good then you can conclude the scanners bolts were loose during data capture.

This will let you know if the sensors were damaged or knocked out of calibration. The fix in this scenario would be to send the device back to Munich for re-calibration and testing, refer here.