Hāpaiali‘i Heiau Repairs
Construction Monitoring with a UAV
At the request of Kamehameha Schools (KS), SWCA Environmental Consultants has been providing archaeological and cultural monitoring support for repairs to Hāpaiali‘i Heiau.
The Heiau is located within the district of North Kona on the island of Hawai'i
along the coastline in the ahupua‘a of Kahalu‘u
It is surrounded by high tide water on three sides, which has caused the northern and southern retaining walls of Hāpaiali‘i to have been impacted by high surf.
Unmanned Aerial Vehicle (UAV) Data Collection
Because of the storm damage, KS undertook to restore the northern and southern walls of the heiau. In September 2020, SWCA's FAA Part 107 remote pilot went to Hāpaiali‘i Heiau to document the site prior to the restoration activities. Post-constructing monitoring was done in December 2020. A DJI Phantom 4 V2 drone was used to acquire videos and thousands of photos of the site.
SWCA's FAA Part 107 certified drone pilot
Hāpaiali‘i Heiau
Drone video of Hāpaiali‘i Heiau
Tidepool on the western side of Hāpaiali‘i Heiau
Pre-Construction Documentation
The UAV was used to document the site prior to restoration allowing for photos and videos taken from unique viewpoints.
Drone footage of the northern wall
The heiau's south facing wall
Post-Processing
Pix4D mapper was then used to stitch and georeference the JPEGs from the UAV into an orthomosaic with 0.4 inch resolution, as well as a Digital Surface Model and 3-D Point Cloud to create highly accurate elevation modeling.
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Post-Construction Documentation
Hāpaiali‘i and Ke‘ekū Heiau
Hāpaiali‘i Heiau
SWCA collected more data in early December to document the heiau walls after restoration. The same 100-ft elevation flight was performed, as well as more photographs and videos of the areas of interest, to compare the site pre and post construction.
Post-Construction Hāpaiali‘i Heiau
Overview of restored Hāpaiali‘i Heiau and Ke‘ekū Heiau
Drone footage of the northern wall, post-construction
The reconstructed southern facing wall
Ke‘ekū Heiau
SWCA also completed planned flights over Ke‘ekū Heiau and the nearby tidepools. The flights were scheduled during the lowest low tide of the month to create more prominent orthomosaics and to document the slightly submerged petroglyphs in the tidepools southwest of Ke‘ekū Heiau.
Ke‘ekū Heiau and petroglyphs
Ke‘ekū Heiau
Ke‘ekū Heiau flyover
Petroglyphs in tidal zone southwest of Ke‘ekū Heiau
Post-Processing Hāpaiali‘i Heiau and Ke‘ekū Heiau
Because both Hāpaiali‘i Heiau and Ke‘ekū Heiau were flown at 100-ft elevation, a highly accurate and detailed image was created of the entire area.
Hāpaiali‘i Heiau and Ke‘ekū Heiau combined orthomosaics
Ke‘ekū Tidepools
The tidal zone located southwest of Ke‘ekū Heiau was also surveyed with a UAV to document the petroglyphs in the rocks.
The area was flown during the lowest tide of the month, when the rocks would be most exposed. The planned flight covered 2 acres at 50 feet, creating an orthomosaic with 0.4 inch resolution.
Using Pix4D and/or ArcGIS Pro, the petroglyphs can be easily identified throughout the area.
A 3-D point cloud of the tidepools was created as well.
After successfully documenting the construction, as well as the surrounding area, SWCA can provide Kamehameha Schools with the detailed orthomosaics in .tif format, the 3-D point clouds in .las format, the Pix4D project files, and hundreds of photos and videos of Hāpaiali‘i Heiau, Ke‘ekū Heiau, and the petroglyphs in the nearby tidal zone.
The Kahalu'u coastline
