Seeing the city’s lava caves via digital 3D modelling.
Technology lets us see inside the city’s subterranean lava caves without ever setting foot in them.
My first encounter with Auckland’s hidden underworld began at the bend of a cul-de-sac on the flanks of Te Tātua-a-Riukiuta (also known as Three Kings). The walk up the long driveway gave little away, other than to indicate we were among the inhabitants of a genteel, leafy suburb.
We reached a platform that was clearly someone’s deck. Now more or less single file, about 50 of us, some clutching cushions, sidled through an outside shower cubicle and then down rough step-like rocks around a tree.
There, the ground fell away abruptly in a scree of rubble and boulders. Descending the rockslide crab-like, my partner and I caused a traffic jam. No one worried. The underneath would wait.
At the base, the ground was still precarious, but flattish, the darkness relieved by strips of lighting placed at the edges. Now more or less upright, we picked our way along the cave floor to find a place beside the side walls on which to perch. The insides dripped.
As we looked up through darkness in this strange and ancient place with little discernible form, there was enough light to see the roof of the cavern, cathedral-like.
Twenty-eight thousand years ago, molten lava had left this sublime building, a sinewy, cooled-rock tube. This was Stewart’s Lava Cave, the architecture of an explosive natural event, a scoria shelter perhaps inhabited long ago. Caves like this are all over Auckland’s volcanic landscape. Some have been burial chambers, others escape routes. One was once used as a mushroom farm, some more recently for parties, a book launch and now for a music recital.
Down below, everything above ceased to exist, the surface a distant memory. When composer Peter Hobbs played his synthesisers and electro-acoustics, joined by Charmian Keay on violin and Maxine Cunliffe on cello, the haunting sound seeped into the rock, animating the otherness of the beneath.
Later, as we scrambled up the rockslide into the light, the below receded into darkness and oblivion, except for the memory of the mystery, the music, the hollow rock.
My second encounter with Auckland’s surreal secret at the end of garages, under manholes and in suburban backyards was in September, in the cylinders of Silo 6 on Auckland’s North Wharf, where the music of the earlier underground event was now the ambient score for Into the Underworld, an exhibition by digital artist Chirag Jindal.
Digital artist. The problem with the term is the technology that makes the art, in this case a lidar (light detection and ranging) scanner. It was placed, with the help of speleologist Peter Crossley, in 11 of Auckland’s lava caves, to blast photons at the surrounding surfaces at 100,000 times a second. When each photon bounces back, the machine calculates how far it travelled, creating a virtual dot in 3D
space of wherever it strikes. As it tirelessly repeats the process, rotating on a pivot and scanning everything around it in its line of sight, the lidar creates a 3D “point cloud” of the cave — in Stewart’s cave, some 98,078,772 points — to capture the 200m of multi-level passages that comprise the labyrinth. Software then manipulates the scientific data to create a 3D model, which Jindal cuts to show as either a vertical or horizontal section.
The images are extraordinary and unsettling — largely black except for a fine filigree of bright white lines marking the texture and bounds of the cave, with hotspots of intensity indicating where the laser pulsed photons, like a negative image in the inverse. You could argue this isn’t art, but architectural representation, the shape and form of the caves depicted with machine-like accuracy in a way never seen before.
The exhibition aims to make the hidden existence of the caves irrefutable — to bring the secrecy into the open, to recover what might be lost and to ensure these natural wonders are protected and valued. Some of these caves have been badly treated, in some cases as rubbish dumps or filled with concrete when discovered on building sites.
The caves, many below private property, sometimes running under several houses, raise multiple questions. Who owns what? How deep do property rights go? Do property owners own the ground to the centre of the earth? Who went here before?
The exhibition’s answer to these vexed questions of ownership, preservation and stewardship is to make precise, exact architectural drawings made of millions of points representing spatial facts, accurate to a millimetre.
What transforms these scientific images into architectural art is the way the underground is combined with what lies above. Enter the lidar again, scanning the surface terrain to show the gardens, the houses, the cars and sometimes the people of suburbia above the caves. The two sets of scans together vividly express the surreal urban context, the past beneath our feet. The above is dreamily photographic, ghostly, sometimes cubist in the way a van might appear superimposed twice and the outline of dwellings is explicit and hyper-real. Adding to the difference between worlds, sometimes trees and vegetation are photoshopped with subtle colour. Then there’s the threshold, sometimes a human intervention — steps, a ladder, a grotto, a vestibule — sometimes a natural rockslide.
With all this technology in play, virtual reality might have been expected as the medium of display. But while the exhibition does have a projected animated flythrough of a digital 3D model of a cave, everything else is presented old-school, in huge curved lightboxes in the manner of Louis Daguerre’s dioramas. The result is enchanting, the backlit panoramas, particularly the sectional views, drawing the viewer into a mystical, fantastical landscape. A world created from light and through light shone from behind. A world that invites dreams.
Over the centuries these caves have existed, people have used them in a variety of ways. But mostly they are precious landscapes that most Aucklanders are unlikely ever to visit. The irony of these images is that they invite just such a magical possibility.
ABOVE— A cave beneath Shackleton Rd, Three Kings, is revealed in a work by artist Chirag Jindal.