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From CAD User Mechanical Magazine  Vol 19 No 06 - JUNE/JULY 2006

ART VPS is pioneering advancements in ray-traced and High Dynamic Range Imaging through its PURE rendering card and RenderDrive workstation

What do you understand by the term photorealistic? Perhaps you take it to mean 'as real as a photograph’, that the thing in question looks as real as it gets (the camera apparently never lies, after all). So how do you differentiate between last year's photorealistic rendering and what you see before you this year - with the latest techniques and capabilities considerably enhanced? How can you improve on photorealism?

It's fascinating to see the computer industry constantly expanding your conception of what is attainable. For example you may have thought that the quality of ink-jet printing couldn't really improve on the current state of the art - yet it always does. And the same is true of rendering. Just when you think that rendered imagery has got as real as its going to get in terms of clarity, depth of field, colour and so on, then somebody announces improvements.

Perhaps a true litmus test of photo-realism might be if a professional photographer, being presented with a mock-up of a car, say, in a particular environment, somewhere that the car could not possibly have been taken, would be fooled into thinking it is the result of a real photo-shoot. Well this is just the sort of breakthrough currently being achieved as a result of developments being made in several advanced imaging techniques - namely ray-traced rendering and HDRI spherical scanning.

Ray-Traced Rendering
As our method of viewing the world is based on the reception and interpretation of light from numerous sources, so rendering must attempt to do the same. A shaft of light comes at us from millions of angles - direct, reflected off nearly every surface in front of you in different hues, or through transparent, translucent and distorting objects. Only a few materials and surfaces experience marginal reflections - for example matt black objects such as tyres.

Perfect rendering follows every path of reflected light, calculating the amount of colour picked up from the material properties of each object it hits, and converting this into digital information, pixel by pixel. There's a lot of activity going on to say the least, requiring some heavy processing capabilities and a fair bit of time - but the quality of the images achieved speak for themselves.

Most of those companies that do use ray-tracing have to compromise. It's not a technique that can be used for real-time rendering, for obvious reasons. Each scene has to be set up and optimised before it can be rendered - selecting, for instance, those elements that won't reflect light and so needn't be ray-traced, setting up different attributes for different materials, and getting rid of rays once they have done their initial job. It's an effective technique that produces high quality images - but much of the light activity has to be surrendered to save rendering time.

Given better hardware, most companies would prefer to give ray-tracing free reign in order to achieve the ultimate in quality. To this end, ART VPS has developed its own hardware; the PURE card and RenderDrive workstation, which features dedicated processors specifically designed to handle the enormous amount of processing needed to handle ray-tracing. The PURE card has 16 of these processors in it, and is used in a single Workstation, whilst the RenderDrive can have 16, 32 or 48 processors, and can sit on a network so that it can be used as a dedicated rendering server, freeing up CAD workstations.

By developing dedicated technology based on hardware processors, ART VPS has raised the bar for ray-tracing. The user no longer needs to spend time optimising the scene before it is rendered, and instead is able to utilise a more of a 'drag and drop' method - saving large amounts of time not only on the initial set-up, but whenever scenes need to be modified.

Proof of the effectiveness of the solution is its recent acceptance by those most critical of users - professional photographers, in particular those working for advertising agencies, who spend their entire working life looking at images of cars. They are starting to use ART VPS hardware precisely because they can no longer tell whether the cars depicted are real or not!

HDRI
Of course, a vital part of any rendered scene is the environment. Because light bounces off all sources, any primary object will reflect everything around it. For absolute realism (if such a thing can be said to exist outside the realm of Platonic philosophy) the surrounding scenery must also be perfect, and the best way to deliver this is using HDRI technology.

HDRI, or High Dynamic Range Imaging can be best achieved for photographic purposes by using a Spheron camera, capable of scanning a 360 degree image around wherever the camera is placed. The high dynamic range refers to the 23-26 range of f-stops (camera optic technology) that the camera can pick up. This is close to the capabilities of the human eye, which can discern dim highlights in near darkness.

The 360 degree scans can then be brought back into the studio to be used as the background model for placing the object. It is this image information that is then reflected onto the computer generated car, creating automatic lighting levels. In this way, scans can be taken anywhere on earth, even places where cars cannot be taken, and used as a backdrop for the vehicle.

The spherical scan can also be used as a light source, so not only does the scene contain ray-traced information from primary sources, such as the sun or from artificial light sources, but it also contains ray-traced light from secondary sources. For example, If you stand next to a wall painted in yellow then the yellow light will form part of the reflections on your skin. Placing the digital model in the digital scenery produces the ultimate in rendered imagery.

All of this helps to make the lighting in a scene more convincing. Rendering solutions that mainly use software in conjunction with the most advanced graphics cards have a nightmare trying to achieve the ends that PURE, literally, renders easy. With ART VPS you get very high quality ray-tracing, allied with very high quality models and HDRI spherical scans to produce lifelike images, allowing users to spend more time being creative and less time fiddling around optimising the rendering.

Market Requirements
We’ve focused here on the car market as a principal user of this technology - but why exactly does this sector need or want to use such advanced methods? One major reason is security. There are people who actually earn a living following car manufacturers around the world in an attempt to be the first to spot and snap the latest models, and to then sell them for large sums to magazines - or their competitors.

There may also be a pressing demand for promotion material for vehicles behind schedule, or it may just be cheaper to send a photo team equipped with HDRI equipment out to an exotic location, rather than sending out brand new vehicles and their support teams.
Being able to produce images that are indistinguishable from the real thing helps sell the products whilst minimising some of the marketing and developing costs. The same principals can equally apply to other industries - even perhaps to the film industry, where digital personalities can be given a touch more veracity through ray-traced rendering, perhaps giving the skin that 'glow' that film stars possess, and that are curiously lacking from digital animations.

Finally, have I fallen into the same trap as before? Have companies such as ART VPS really achieved genuinely lifelike images - or can things get even better from here? Can we really get even realler than the real thing?!

www.artvps.com

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