Strip Align Error: "failed to compute BF/ICS tables"

🛠️ Problem

Strip Align Fails with the following error while running Strip Align:

ERROR: failed to compute BF/ICS tables
ERROR: correction failed

This guide outlines the likely causes and steps to resolve the issue.

🔍 What This Error Means

This error typically occurs during the registration phase of Strip Align when the software fails to compute the Bayes Filter (BF) or Initial Correction Surface (ICS) tables. These are critical for aligning overlapping LiDAR swaths.

🧪 Common Causes

• Insufficient or inconsistent swath overlap
• Poor trajectory or IMU data quality
• Excessive noise or misalignment in point clouds

✅ Probable Resolution#1

Check Swath Overlap and Quality:
Ensure your flight lines have adequate overlap. Use overlap and density images (e.g., out_ovr, out_mD) to verify coverage.

✅ Probable Resolution#2

Evaluate Trajectory and IMU Quality:
Poor IMU data can prevent successful alignment. Ensure proper flight maneuvers (e.g., box turns) were performed.  The Flight Planning - LIDAR document emphasizes the importance of heading alignment maneuvers and box turns to improve IMU output.

✅ Probable Resolution#3

Test with Subsets:
Process individual flights separately to isolate problematic data.

✅ Probable Resolution#4

Review Logs for Pair Registration:
Check if swath pairs were valid but failed to register. This may indicate incompatible densities or poor feature matching. This could point to:

• Excessive noise or misalignment
• Incompatible point densities