# Trajectory Optimization

Trajectory optimization involves adjusting the lidar system's trajectory, which in turn changes the position of the lidar points. Position (south, east, up) and attitude (roll, pitch, yaw) can be adjusted by the optimizer at any point along the trajectory in order to achieve better agreement between lidar data from different times along the trajectory. Trajectory optimization can also be used to adjust lidar data towards ground control points. 

LiDARSnap offers two presets for trajectory optimization - **Airborne Trajectory Optimization** and M**obile Trajectory Optimization**. Each of these presets contain a set of parameters that have been found to work well with their respective data set types, however all parameters can be modified by the user. The mobile trajectory preset optimizes for all parameters (south, east, up, roll, pitch, yaw) at a very fine spline interval (every 2 seconds), whereas the airborne trajectory preset only optimizes the vertical parameter (up) at a coarser interval (every 10 seconds). 

The result of trajectory optimization is a POF trajectory created by LiDARSnap:

<figure><img src="/files/qt3sHF1vVX1vYtR74b3K" alt=""><figcaption><p>POF trajectory (yellow) produced by LiDARSnap trajectory optimization</p></figcaption></figure>

SpatialExplorer will automatically recompute the point cloud in respect to this new trajectory; however, if the optimization results are satisfactory, it is recommended that you save the pointcloud and PLP before proceeding with classification, colorization or any other processing.&#x20;


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