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:

  1. There must be no material within 1.5 m range of the scanner. The scan position should be moved a short distance if necessary.

  2. 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