Spectacular Barron Gorge accurately modeled by LiDAR in record time!

Brett O’Hagan, LiDAR Co-ordinator

AAM acquired LiDAR data over the World Heritage listed Barron Gorge near Cairns, Australia. The 8 square kilometres of unique landscape and heavy tropical rainforest canopy required detailed planning to ensure the maximum number of laser strikes reached the ground; while at the same time providing intricate detail of the rocky gorge.

Water flow through the gorge was stopped 3 hours prior to acquisition of LiDAR data allowing enough time for the water to flow away from the target area. The result was the most accurate spatial dataset ever produced over Barron Gorge.

LiDAR acquisition settings were tailored specifically to meet the project’s requirements. Acquisition was designed to maximise the penetration into the gorge and through the vegetation. Additional runs were added and orientated to fly directly down the gorge enhancing the definition of the water flow area. In total 27 million points were collected over the target area with 1.5 million strikes penetrating the tree canopy and modeled as ground strikes.

While the primary objective of the survey was to obtain an accurate terrain model over the gorge itself, secondary objective was the structure of the watercourse where massive "goolies" (boulders) lay. Before data was collected the gorge was inspected on-site. The waterflow area was deemed to be free from vegetation allowing it to be modeled accurately. The LiDAR data within this area was unfiltered and the “goolies” were modeled as part of the terrain surface. The height profile and models below demonstrate that thick vegetation is no match for a LiDAR sensor when planned carefully.



<    All laser strikers modeled showing both terrain and tree canopy







 <   Ground-only laser strikes are modeled in the right Digital Terrain Model








<   3D Perspective View of Barron Gorge derived from LiDAR data

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