Dataset
SPLICE: Terrestrial Laser Scanning (TLS) for UK Alice Holt plot AH2, July 2023
Abstract
Terrestrial laser scanning was collected on the 18th July 2023 by Mat Disney and Meg Stretton using a Riegl VZ-400i for the SPLICE project. The data was collected at the Alice Holt Forest, which is an ancient mixed woodland spanning approximately 850 hectares on Gault Clay and Upper Greensand soils at the north-western edge of the Weald in southeast England.
Scans were acquired using chain sampling at 34 locations along a 12.5 m Cartesian grid to ensure sufficient data overlap to produce a high-quality point cloud of this forest plot. Capturing a complete sample of the scene at each location requires two scans (an upright scan and a tilt scan), owing to a 100° field of view. Upright scans are odd-numbered while tilt scans are even-numbered. The angular resolution between sequentially fired pulses is 0.04°, resulting in approximately 22.4 million emitted pulses per scan (i.e., 5.42 billion per ha). Up to four targets can be resolved per pulse, with a nominal ranging accuracy of 5 mm. The laser itself is characterized by a beam divergence of 0.35 mrad, and the diameter of the beam at emission is 7 mm (e.g., the diameter of the beam at a range of 50 m, would be 21 mm). The pulse repetition rate is 300 kHz, therefore, each scan takes approximately 3 minutes to complete.
To generate a plot-level point cloud, scans were coarse registered using GNSS enabled Auto-Registration 2 (AR2) with coarse registration fine-tuned using Multi Station Adjustment 2 (MSA2). The Sensor's Orientation and Position (SOP) matrix for all scans was saved into the "matrix" project directory and the GNSS coordinates (geographical coordinate system: WGS84 Cartesian) for all scans saved as a .kmz file.
For more information please see the Site_and_data_collection_and_processing_details-2.pdf and SPLICE_example_TLS_data_directory_structure-1.pdf documents archived with the data.
Details
| Previous Info: |
No news update for this record
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| Previously used record identifiers: |
No related previous identifiers.
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| Access rules: |
Public data: access to these data is available to both registered and non-registered users.
Use of these data is covered by the following licence(s): http://creativecommons.org/licenses/by/4.0/ When using these data you must cite them correctly using the citation given on the CEDA Data Catalogue record. |
| Data lineage: |
Data were produced by the project team and supplied for archiving at the Centre for Environmental Data Analysis (CEDA). |
| File Format: |
The following terrestrial LiDAR-derived products are available the Alice Holt plot:
1. Raw terrestrial LiDAR data from each scan (no filtering was applied in RiSCAN PRO), stored in
the RXP data stream format developed by RIEGL.
2. Transformation matrices necessary for rotating and translating the coordinate system of each
scan, into the coordinate system of the first scan. Stored in DAT format.
3. Pre-processed terrestrial LiDAR data:
a. full-resolution 10m tiled plot point clouds including attributes such as XYZ, scan position
index, reflectance, deviation, etc. stored in polygon PLY format.
b. downsampled 10m tiled plot point clouds including attributes such as XYZ, scan position
index, reflectance, deviation, etc. stored in polygon PLY format.
c. A tile_index file (maps the spatial location of the tiled point clouds) stored in DAT format.
d. Bounding geometry files setting plot boundaries with and without a buffer surrounding the
plot. Stored in shapefile SHP, DBF, SHX and CPG formats.
4. Downsampled 10m tiled plot point clouds segmented into leaf, wood, ground points or coarse
woody debris. Stored in polygon file format PLY format.
5. Wood-leaf separated tree-level point clouds including segmentation results and classification
probabilities for each point are stored in polygon PLY format.
6. QSM files:
a. in_plot CSV (for plots processed with TLS2trees) lists all trees to be modelled with QSMs
as they are located inside the plot boundary.
b. out_plot CSV (for plots processed with TLS2trees) lists all trees NOT to be modelled as
they are located outside the plot boundary.
c. plot_boundary CSV (for plots processed with TLS2trees) shows the location of all
in_plot trees within each plot boundary.
d. QSM processing files (.MAT Matlab).
e. QSMs derived from each woody tree-level point cloud, (.MAT Matlab)
7. We provide pre-processed and segmented terrestrial LiDAR data in PLY format as it supports
full 3D object representation, including polygons and geometric primitives, in addition to point
data. This is essential for storing quantitative structure models (QSMs), which go beyond point
clouds to describe tree geometry. The PLY format is open, widely supported in Python and R,
and can be converted to LAS/LAZ when only point data are required.
8. Tree-attributes file (.CSV) containing biophysical parameters derived from both the point clouds
and QSMs: DBH, tree height, tree-level volume and AGB with uncertainty, plot-level AGB and
associated uncertainty.
9. Figures of all individually segmented trees arranged by tree DBH size (largest to smallest DBH)
for each FBRMS plot(PNG image format).
10. GNSS coordinates (geographical coordinate system: WGS84 Cartesian) for all scan positions
stored in KMZ zip-compressed format. These files are available for the seven French Guiana
and Gabon FBRMS plots.
More detail can be found in the Site_and_data_collection_and_processing_details.pdf document archived with the data
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Related Documents
Process overview
Independent Instruments
| UCL REIGL VZ-400i Terrestrial Laser Scanner (Serial #: H2226750) |
| Output Description | None |
No variables found.
Temporal Range
2023-07-17T00:00:00
2023-07-18T00:00:00
Geographic Extent
51.1556° |
||
-0.8648° |
-0.8639° |
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51.1551° |