Leica ALS50-II LIDAR
The ARSF LiDAR system, for data collected in 2009 onwards, is a Leica ALS50-II. This includes a full waveform upgrade for 2010 onwards.
The ALS50-II operates with a 8W class 4 laser with radiation at 1064 nm. It works by firing a 4ns or 9ns pulse and measuring the round trip time to when a reflection is detected. This is then converted into a distance. There are 2 banks of timing cards - each one with 4 cards. This means that it can measure up to 4 independent returns for each pulse (it only uses the 2nd bank of cards when operated at the higher pulse rate). A minimum time separation between two returns means the minimum distance between two returns must be at least 2.7m for them to be counted as independent.
A lot of the system specs can be (and are) changed to tailor for individual flight purposes. If you need to know certain parameters that have been used for a specific flight that are not included in the delivery documents then please contact us. The listed parameters here are min/max values - not necessarily used for a specific collection.
|Beam divergence (mr)||0.22|
|Max FOV (degrees)||75|
|Laser power||0-8W (controlled by operator)|
|Max rate of acquiring waveform||120KHz|
Raw data format
In the form of binary "SCN" files, which contains the raw data using compression and bit-masking. Can be viewed using the Leica SCNviewer graphical interface that comes with the Leica processing software. The files contain data records of ~32 bytes for each point.
Full waveform has the additional files that contain the digitised waveform (.LWV extension). These are binary and you get separate files per range bank with A or B postfix.
For more in-depth and technical information about the sensor and processing please see the following pages. Note that these are written primarily for internal use and so may be technical in nature.
Data quality reports
More details on the LiDAR system and any known data quality issues are covered in more detail in the data quality report which can be downloaded from the reports page.
- Sensors/LeicaLIDAR/MikesNotes - Mike's notes on the Leica training course in Aug 2008 (to be digested and turned into real wiki pages at some point in the future).
- Sensors/LeicaLIDAR/MarksNotes - Mark's bullet notes on the Leica training course in Aug 2008.
- Sensors/LeicaLIDAR/MashUp - The digestion of both sets of notes.