This dataset is comprised of raw data from the NERC-funded, full waveform terrestrial laser scanner (TLS) deployed at sites on three continents, multiple countries and plot locations. Approximately 600 branches were harvested, had their leaves removed and were scanned in a controlled environment. More information can be found in Wilkes et al. 2021. Terrestrial laser scanning to reconstruct branch architecture from harvested branches in the documentation section.

A RIEGL VZ-400 terrestrial laser scanner (RIEGL Laser Measurement Systems GmbH) was used for all scans. In all, 1–6 branches (dependent on branch size) were arranged in a group, orientated so that they would not touch each other or the ground, and scanned simultaneously. Branches were secured in the end of metal tubing and placed in buckets of sand to minimise movement. Fiducial markers (akin to QR codes) were placed on the floor to allow identification of each branch in post-processing. The markers include a pattern of four retroreflective stickers (10 mm ∅) which were used to co-register scans. Between four and six scan positions (collectively known as a project), located around the branches, were used to capture each set of branches. At each position, a single scan was performed where the scanner rotation axis was approximately perpendicular to the ground plane. A 100 degrees × 80 degrees field of view was captured at an angular resolution of 0.02 degrees ; each scan took 2:45 min where ∼20M laser pulses were fired.

The VZ-400 beam has an exit diameter of 0.007 m and a beam divergence of 0.35 mrad; branches were at a maximum distance of 5 m from the scanner, and at this distance maximum cross-sectional beam diameter is ∼0.01 m. The scanning area needed to be large enough to allow easy movement around the branches and minimum distance between the scanner and target (for the RIEGL VZ-400, this is 0.5 m). It should be noted, owing to the restricted scanning field of view, large or featureless areas required additional ‘features’ (e.g. furniture in the scanning field of view) to assist with registration. Initially, scanning was performed outside but it became clear that branch tips would oscillate even with very low wind speeds; therefore, scanning was moved to an indoor space. Co-registration of scans in a project is a two-step process (coarse- and fine-registration) that produces a 4 × 4 roto-transformation matrix for each scan position. When applied, a scan is rotated into a common, arbitrary coordinate system (nominally referenced to the first scan position).

Co-registration of a project was done using RiSCAN Pro (version 2.5.1; RIEGL Laser Measurement Systems GmbH). Coarse registration was achieved using the retro-reflective stickers on the corners of the fiducial markers. Fine registration was computed using RiSCAN Pro’s Multi-Station Adjustment (MSA) method (RIEGL Laser Measurement Systems GmbH, 2019). MSA fits a set of planes to a point cloud by iteratively voxelising the point cloud, with each iteration voxel edge length decreases until plane fit error is below a specified threshold (or no plane is fit if voxel edge of minimum number of point thresholds are exceeded). Here voxel edge length decreased from 1.024 to 0.064 m, minimum points were 10 and maximum plane error was 0.006 m; this resulted in 7,000– 20,000 planes per scan position. MSA then uses a least square solution to iteratively adjust scan position to minimise positional error between overlapping planes.