Terrestrial Laser Scans Protocol

Figure 1: Apparent reflectance (left) and range (right) hemispherical images from Riegl VZ400 scans at the Queensland DES GOLD0101 long-term monitoring plot.

Ground lidar, also known as Terrestrial Laser Scanning (TLS), is a ranging instrument that provides detailed 3D measurements directly related to the quantity and distribution of plant materials in the canopy. Measurements can be used for applications requiring quantification of vegetation structure parameters, tree and stand reconstruction, and terrain analysis.

Sampling Strategy

Data is collected at one or more sampling points at a plot, depending on the protocol. There are currently five separate sampling protocols used for ground lidar acquisition. The sampling design for each protocol with multiple scan positions are illustrated below. The specific protocol used and deviations from this strategy are outlined in the associated shapefile/KMZ file for this data set.

Plot centre (single scan)
Star transect (four scans)
Cross 40m (five scans)
Cross 25m (five scans)
Square (five scans)

When a scan position was established, the scanner was set-up as follows:

There must be no material within 1.5 m range of the scanner. The scan position should be moved a short distance if necessary.
The nominal height above ground of the scanner is typically 1.6 m. Scanner height is determined from the measured data.

Instrument data filenaming convention

Filenames for instrument data conforms to the AusCover standard naming convention. The standard form of this convention is:

<sensor category code><instrument code><product code>_<longitude>e<latitude>s_<yyyymmdd>_<processing stage code>_<additional dataset specific tags>

Details for the unique codes used for this dataset can be found in the following table.

Data Naming Element	Possible Code(s)	Descriptor

Data Naming Element	Possible Code(s)	Descriptor
Standard Elements
sensor category	gp	ground lidar
instrument	v1	Riegl vz400
product	wf	waveform
processing stage	aa0 aa1 aa2	raw instrument data (sensor coordinate system) registered data (project coordinate system) registered data with waveforms and photo RGB data
data projection	f0 f1 f2 f3	Time sequential Scan line/sample Cartesian Spherical

Shapefile/KMZ file attribute metadata

Field	Description (units)	Format

Field	Description (units)	Format
supersite	AusCover calibration/validation site	Text
collection	Code in naming convention –see instrument filenaming convention for details	Text
instument	Code in naming convention –see instrument filenaming convention for details	Text
product	Code in naming convention –see instrument filenaming convention for details	Text
scene	Identifier for plot location given in longitude latitude combination	Text
obs_time	Date and time of scan collection	Date/Time Stamp
scan_azimuth	Azimuth of transect from plot centre to scan collection point in degrees from north (degrees)	Integer
height_base	Height from base of scanner plate (cm)	Integer
height_optical_centre	Height optical centre of scanner plate (cm)	Integer
battery_on	Yes/no categorical field whether battery is on scanner, as this affects height measurements	Text
reflect_distance_n	Distance to reflector on north transect, if exists (m)	Float
reflect_size	Reflector diameter (mm)	Integer
project_name	Project root name as recorded in scanner	Text
obs_key	Unique identifier for site visit for data management purposes	Text
id	Id for data management purposes	Integer
reflect_found	Number of reflectors scan found	Integer
tilt_angle	Tilt angle of scanner (degrees)	Integer
no_reflect	Total number of reflectors deployed
scan_distance	Distance to scanner along transect running from plot centre to scanner location (m)	Float
reflect_distance_s	Distance to reflector on north transect, if exists (m)	Float
reflect_distance_e	Distance to reflector on north transect, if exists (m)	Float
reflect_distance_w	Distance to reflector on north transect, if exists (m)	Float
reflect_distance_ne	Distance to reflector on north transect, if exists (m)	Float
reflect_distance_se	Distance to reflector on north transect, if exists (m)	Float
reflect_distance_sw	Distance to reflector on north transect, if exists (m)	Float
reflect_distance_nw	Distance to reflector on north transect, if exists (m)	Float
live_basal_area	Basal area estimate obtained via basal area sweep for live trees only (km/m^2)	Float
total_basal_area	Basal area estimate obtained via basal area sweep for live trees only (kg/m^2)	Float