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From CAD User Mechanical Magazine  Vol 22 No 6 - JUNE/JULY 2009

David Chadwick looks at the way Shaderlight from ArtVPS can deliver massive productivity and creativity improvements over traditional ray trace rendering engines

The reason why traditional ray traced rendering is so time consuming is that the processor has an awful lot of work to do. To illustrate the point it is probably best to follow the path of a single beam of light hitting the surface of a digital model. Start with the light itself, which may be natural or artificial, and if artificial, filament or neon based, with varying intensities and colours. Each of these will provide a different response when they are reflected off the surface of the object. The composition of the object itself will also govern the light's behaviour, with different materials, surface textures and colours dictating how much, and what sort of light is reflected. To produce such an effect, the software must work at pixel level - calculating what will happen at each point of colour on the screen. It doesn't just stop there, though, as the ray of reflected light bounces off and hits another surface, and another, within its own environment, accumulating reflected data as it progresses. The environment could be the interior of a building, with reflective mirrors, transparent glass and shag-pile rugs, or an exterior shot with mountain scenery and trees that will be reflected from the hubcaps of the digital model of a car. Yes, I know, hubcaps are a bit passé, but you get the idea. To throw in a bit more complexity, none of this happens in isolation to the next ray of light, or an adjacent pixel, as each governs the behavioural response of the rest. You can now see why they call the process ray tracing. The amount of work that the computer has to do to simulate such a natural process is determined by the resolution of the image - i.e. the number of pixels - that it has to work on, and the extent of the ray tracing that has to be followed. You can follow the rays of light into infinity, but the effect that will have on the photorealism of the rendered scene falls off after so many

bounces. The usual trade-off applies image quality versus processing time. If you want hyper-realism, then you must be prepared to wait for the processor to do its job. What’s more, all of this is just for a still image. Move the viewpoint - or the image by one degree and you have to start over again!

We are back in the early days of cartoon creation in the cinema, where each still has to be created from scratch. Move one pixel, and the scene is different - rather like the butterfly fluttering its wings in the Pacific and creating a typhoon in India! But all of this is set to change.

A RAY OF HOPE Imagine being able to make changes to the attributes of key objects within a scene at any time, and then to continue the ray tracing of the scene without having to start the process all over again. Imagine not only being able to make progressive refinements to a scene, but to accommodate changes to lighting, materials, the environment and textures as well, whilst continuing to render the same scene!

ArtVPS has made a quantative leap forward with its Shaderlight, a physically based, progressive ray-tracer that enables interactive, nonlinear changes to the key MELT attributes (materials, environments, lighting and textures) at any stage within the rendering process. It enables the rendering process of animated scenes to be dramatically speeded up.

Designers will no longer have to throw up their hands in horror when clients suggest a couple of minor tweaks to an object or a scene, yet can't understand why that will throw the production schedule out. It will help them become more innovative, as their creative instincts will no longer be constrained by the treadmill of render time whenever they move elements of the scenery around.

And, to bring the benefits of the new interactive shading technology to the public that much faster, ArtVPS have made it available as a free download. Early adopters of the technology will be

encouraged to help shape the software by becoming part of the Shaderlight online community (www.artvps.com/content/discuss) providing valuable feedback during the key final phase of product development. Admittedly it is only available as a plug-in for Autodesk's 3ds Max, but it's early days for Shaderlight 0.1, and ArtVPS is so confidant that this is the way the technology is moving, that they want the word to spread fast.

So, what's different? First of all, you need to understand where the term MELT comes from. It’s shorthand for Material, Environment, Light and Texture - the four elements that can be changed at will in the rendered scene. The software works by rendering intelligent pixels that understand where they fit in a 3D image - and what to do if something changes. When changes are made to these four elements, the information embedded in each pixel can be used to update the image without the need to re-render. These are called MELT changes.

Each pixel, therefore. holds additional MELT information, which the software can utilise. There is a slight drawback. It takes longer to download the initial data for the first render. Subsequent renderings,

however, more than make up for that.

MELTING MOMENTS What, precisely, does that give you? For Materials, the parameters of 3ds Max or Shaderlight material settings can be adjusted instantly, even on final images. HDR Environments of back plates can be replaced, updated and enhanced for a dramatic change of atmosphere. Lighting intensity and colour can be adjusted at will, automatically re-positioning reflections and shadows without having to re-render, and texture maps and settings within scenes can be applied or adjusted over and over until the perfect finish is attained.

Shaderlight users don't only see the progressive refinement of a scene when objects or camera angles are altered - the software will also allow them to make interactive changes to the MELT elements on full quality 3D images.

The first users of Shaderlight - admittedly part of the initial development process of the new software - are already seeing massive benefits from the software. "As a CG artist I often have to work with clients who have no real idea of how long even the slightest change to an image can take to re-render," says Olaf Finkbeiner, CGI operator at Mainworks GmbH Germany and a member of the Shaderlight Product Steering Committee. "The ability to make changes to materials or environments on a final image would save us days of re- rendering - and in this industry time is money."

According to Michael Lawson, CTO at ArtVPS "This is an exciting time for everyone at ArtVPS. After 18 months of hard work we are delighted to launch Shaderlight 0.1., which stands to fundamentally change the way 3D artists and visualisation specialists go about generating images". He pointed out that the software was developed on the back of user experiences, and that "the time and cost savings that Shaderlight will bring are invaluable in terms of improving efficiency and project turnaround. CG professionals need never compromise on the quality of their final output again." www.artvps.com

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