GeoCode LIDAR Point Cloud Task

The GeoCode LIDAR Point Cloud Task is used to convert laser scanned range data to LAS format projected LIDAR Points

This function is accessed from the GeoCode LIDAR button on the TrueView Workflow Toolbar. ID invokes the GeoCode LIDAR dialog.

Flight Line Layer - Select the flight lines that are to be geocoded.  It will automatically default to the topmost flight line layer in the Table of Contents (TOC).  If more than one flight line layer exists in the TOC, it can be selected via the dropdown.

Only Use Selected Flight Lines - If you want to process a subset of flight lines on a layer, select the desired flight lines using the Feature Edit select tool and check the box “only use selected flight lines” on the dialog.

Calibration File - Options to define which Calibration file to use when GeoCoding data. The Calibration files imported with the Cycle file may not be the most recent one available for your sensor. LP360 automatically checks for an updated calibration file.

Use Latest Calibration File - Selects the most recent calibration file.

Use Current Calibration File - Select this option to use the file imported from the Cycle file. Use this option if no updates are available via Latest Calibration Date.

Manually Select Calibration File - Use to override the automatic selection of the calibration file.

LIDAR Clipping

Clip Angle - Clips cross track scan line to ±"Clip Angle" from Nadir.

Clip Range - This will remove points that are beyond the entered value from the sensor.

Enable True Track - Dynamically adjusts the Nadir position based on aircraft roll resulting in LIDAR swaths that are straight on level ground. (Default Processing Mode) True track is our term for software-enabled roll compensation of the sensor. The roll attitude of the sensor (due to roll of the drone carrying the sensor is constantley reset to the nadir position and clipping if set) applied at this point. The effect is flight lines with straight rather than wavy edges. You should always enable True Track. For a given clipping angle, it will produce more accurate as well as better aligned data. Figure 77 shows a LiDAR swath clipped to 20° but with True Track disabled. Notice the waviness in the sides of the track.

Noise Filter: (Riegl sensors only) Enabled by default when processing Riegl laser scanner data, this option will help automatically filter noise points from being geocoded. A user would not normally disable this option but may wish to do so when the density of the point cloud is more important than the accuracy of the points.

How to GeoCode LIDAR

1. Click the GeoCode LIDAR button and the dialog below opens.

2. Verify the correct _FlightLines layer is selected. You can chose to generate lidar data for all flight lines on the layer (default) or just lines you have selected in the map view.

3. Determine what Lidar Clipping you want to perform when generating the point cloud. You can configure TrueView to clip the data based on angle (degrees from nadir) or range (distance from sensor). Best practice is to clip the data to no more than ±40° from nadir and not clip the range. However, both parameters can be adjusted depending on the project specifics.

4. Verify True Track is enabled.  True Track provide roll compensation during geocode to maintain the lidar swath remains centered around nadir. Turning True Track off will result in ragged line edges if the UAV was rolling significantly during flight.

5. When ready, click GeoCode Lidar.

As GeoCode runs you can monitor the status bar in the lower left corner of the GUI. LP360 will generate a .LAS file for each flight line sequentially and add it to your project on a new layer named _LAS. You will also see the lidar data start to display in your map view line-by-line. The .LAS files that are created by GeoCode are placed in the Flights\LAS folder.  Each file will also have an associated .QVR file. This is the pyramid file for LP360 display.