A while back I nearly didn’t answer the phone. It was one of those international numbers and I didn’t recognise it but something told me to pick it up. I spent the next 30 minutes chatting to John Kinsella of Ocean Divers in Ireland all about 3D reconstruction and how it could be used in a virtual diver training world. Being slightly sceptical I was unsure…but I’m glad I took the call as it transported me into a virtual world…this week I did a nitrox dive in Second Life.
Second Life is one of those websites thats been kicking around for a long time and generated a little controversy in its day. I had heard about but had little reason to visit. Life was busy enough without adding a second one into the mix but John explained an enriched air diver training course in the immersive world it piqued my interest – could we add a real-world wreck into the scene and let divers explore it?
John was keen to upload the SS Thistlegorm model. Whilst the wreck is the one everyone has either dived or wants to the 3D model is massive. It wasn’t clear Second Life could handle it and there was a hard limit of 19,000 facets on any model. The lowest resolution model of the Thistlegorm was just over 3 million faces…
So we plumped for a smaller wreck. I had just finished reprocessing the Froach Ban, a fishing boat sitting at a depth of 30m in the Shetland Isles, so why not use that?
With the model reduced to a mere 19k facets it seemed a little blocky and primitive but we are dealing with a technical and hard limit.
As a reminder it can be very useful to decimate your model before uploading to sites like Sketchfab. A model with massive detail will look great on the PC at home. The average Sketchfab viewer is likely to want to look at something quickly and use their phone…having millions of facets slows things down or crashes phone app…so as a guide anything on Sketchfab is best limited to 1 million facets or so (for now at least).
Decimate is found under the Tools -> Mesh menu and is available in both Standard and Professional editions.
There can be a lot of hype about facets and the level of detail. More is perceived as better but this view can be flawed; a cube can be resolved in just 12 triangles and be perfect. A tetrahedron takes just 4. More is not always better when applied to detail and 3D models.
Into the Virtual Deep
A few weeks later an invite into the Second Life world created by the team arrived. I logged in and after a few toddler steps figuring out how to negotiate the virtual world I found myself dressed in full SCUBA kit and a tank full of digital 32% nitrox. The first lesson? In the virtual world you can walk in fins…but there is much more to the educational side of this. Its clear a lot of work has gone into the training and simulation (by Philippe Carrez of Immersion Tools) that runs behind the interface.
Nitrox is one of the few courses you can complete and not get wet and is a good fit for virtual skills. The dive computer display gives you depth, time, tank pressure etc and you really do have a bottom time counting down, all based on real world absolute values. Air consumption is set at 21l/min and the in water time and depth physics dictate remaining dive time.
Detail is Everything
Anything immersive needs massive detail to feel real. Second Life is going to struggle with the model facet limit but it was clear a lot of effort had gone into the lighting, fish and coral (Loly Sirnah built the scene in the region) to give a feeling of immersion. I couldn’t help to want to explore in the gin-like conditions.
In this new world its easy to suspend reality. We went from a northern hemisphere Shetland wreck in temperate seas to tropical reef in just a few seconds and there were Orca and sharks aplenty.
Will I be giving up real world diving for Second Life?
No, definitely not. But thats not really the point. As a virtual training tool you can plan and conduct a dive on air then turn around (no surface interval) and repeat on any mix of nitrox you like and check out the differences.
This kind of training will never replace the real world divers experience with its tides, variable visibility and their infinite variability but there is a reason pilots train in simulators and real-world scenarios worked through to embed process and procedure into the mindset.
Why not divers too?