Tuesday, 26 January 2010

Halo 3: ODST - Tech Analysis

As our first feature here at IQgamer, we though of nothing better than to start off our hopefully long-running and thoroughly insightful technical reportage, with none other than Halo 3 ODST, the latest title in a series which introduced many gamers to the world of beautifully textured, bump-mapped and overly shiny first person shooters. A series which although seems to have lost a large amount of its visual clout, still pushes certain things forward technologically that other AAA games lack altogether, even if the end result requires some unpleasant side-effects.

Before we go on, I would like to point out that ODST is essentially using the same tech built up for Halo 3 with some of the same shortcomings as that title, then simply enhanced and refined for this latest instalment. So with that, we still have the use of the dual 1152×640 frame buffers, which are combined to form a final 1280×720 image, and used to save enough bandwidth to allow the full range of HDR lighting to be displayed, whilst sill fitting the frame buffer into the 10mb edram available. This also means that there is no room for a proper MSAA solution due to the memory constraints, nor is there a clear way using a respectable amount of anisotropic filtering to clear up any blurry far away textures.

However that’s not to say that some of the issues which plagued Halo 3 haven’t be dealt with, because despite the limitations of the engine used they clearly have to the extent their current technology allows.

Firstly, the jagged edges caused by both the lack of any AA being applied, and the upscaled nature of the dual framebuffer solution, have been considerable reduced increasing overall image quality noticeably. The game appears a lot sharper than Halo 3 in most situations and this improvement is very welcome allowing for the textures to stand out, and a detail increase without upping texture usage. Now ODST achieves this clarity, not by a traditional MSAA algorithm but by some kind of post process filter, which subtlety smoothes over most of the upscaling artefacts and a large part of ODST’s jaggies. The effect understandably is less pronounced than regular MSAA in certain situations, particularly those with smaller, more intricate details, and in some indoor scenarios - in which the game appears to lose this edge smoothing filter and brings back a screen full of jagged edges and a slight loss in texture clarity.

This apparent breakdown of the games AA solution largely depends on what filters are being used for any given scene, and is mainly used to add realism to the games visual look rather than just a cheap use of anti-aliasing. So it’s a nice inclusion to see it here rather than a tarnish to the games competent, and sometimes lovely visual splendour.

Texture filtering has been slightly improved upon since Halo 3, though still using plain old bilinear, greater clarity is achieved via a bias to filtering certain textures more than others. This system saves on the heavier memory requirements that trilinear filtering would bring whilst allowing detail to be visible for longer distances, thus giving a cleaner look. However this method whilst still allowing for the increased use of HDR, and the inclusion of new post process filters due to saving memory, only goes so far to helping the majority of the games textures, which still suffer form the slightly blurry look, just covered up slightly by the better transitions between texture samples used during the filtering. Of course the ones which have had the bias applied come out much better, but still a far cry from the clarity displayed by the far sighted texture work of PS3’s Uncharted or the lesser filtered 360 Gears Of War.

Overall you have a cleaner look in ODST when compared to Halo 3 but one which falls short of many games this generation.

ODST does have more than just AA and texture improvements though. Geometry on both the human and covenant characters for one, have been reworked with better application of normal mapping creating a more organic look and losing some of the plastic look western dev houses seem to prefer. Brutes in particular, when losing their armour have increased detail, as well as looking more rounded than before, making them much easier on the eyes, just like their human counterparts. And of course much of this seems to come from better blending and shading techniques rather than raw geometry increases.

These changes mean that characters react with the lighting model more accurately than before, with global lighting affecting local shadows and characters to a greater extent, even though some of it is simply calculated shadow maps rather than true dynamic lighting. The fact that it works very well, regardless of how certain aspects have been cheated or better put, pre-calculated, shows how you don’t need to have the most accomplished and accurate shading and lighting model to get convincing results.

So, it seems that all of ODST’s tech have come from optimising the existing Halo 3 engine, adding new features which help solve some of the issues they faced before, but without taking away any of their accomplishments with the stellar lighting model, creating a cleaner more concise visual picture which although still suffers from some problems has obviously been pushed as far is it can go.

With all that said and ODST done and dusted, it will be interesting to see where Bungie take their new engine currently in development with Halo Reach. Will they pair down the show stopping but memory heavy HDR solution, increasing overall image IQ through proper 2xMSAA and at least trilinear filtering, or will they surprise us with something else entirely like adding SSAO to the mix?

Personally I’d like to see better IQ and the addition of SSAO over having the maximum range of available lighting, not unlike Uncharted 2, which not only manages to squeeze a lot more under it’s hood, but come out cleaner and far more visually impressive to boot. Of course we’ll be discussing that one another day.

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