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Terrestrial Laser Scans Protocol
- Rebecca Farrell
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 |
|---|---|---|
Standard Elements |
| |
sensor category | gp | ground lidar |
instrument | v1 | Riegl vz400 |
product | wf | waveform |
processing stage | aa0 | raw instrument data (sensor coordinate system) |
data projection | f0 | Time sequential |
Shapefile/KMZ file attribute metadata
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 |
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