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Brazil r/s - First Look
by Todd Sheridan Perry
Brazil R/s - A First Loo
There are a lot of renderers on the market today. Some make heavy-duty claims.
Some can live up to them. Others are just vaporware. There is one renderer
due to be released any time, which looks to be one of the contenders. This
product is called Brazil r/s.
Brazil r/s is a high-end renderer, fully integrated with 3ds max and 3ds
VIZ.
It takes advantage of new developments in digital imagery, providing advanced
and selective ray-traced reflections and refractions, global illumination,
area lights and shadows, sub-surface scattering, depth of field, camera modeling,
caustics and HDRI support, all contributing to more control over and flexibility
with computer generated imagery. Brazil r/s sits on the base of a ray tracing
engine, supplemented with rendering subsystems that are and will be pluggable
into the base architecture. This will allow Brazil r/s to expand further and
further as new technologies develop.
Some of the current and planned for features of note are listed below.
Full-latitude Data
The images rendered from Brazil r/s have full latitude data, containing
a full range of image data based values that represent the amount of light
a pixel stores. This information goes well beyond the 0-255 values that a
computer screen will give you. It uses floating-point values like 0.523, and
135,000.385, as examples. So, the range of colors and luminance are vastly
greater and the values are much closer to how film responds, in a chemical
way, to light. This gives more data to visual effects artists for integrating
the CG imagery into live-action plates that were shot on film. It is also
beneficial to architects, because the resulting imagery will give their clients
a more accurate view of how their future building will look once its built.
Max itself does not support the color range of HDR images, so Splutterfish
has plans to release a supplemental I/O plugin to complement and control these
features.
Brazil r/s provides
advanced and selective ray-traced reflections and refractions, global illumination,
area lights and shadows, sub-surface scattering, depth of field, camera modeling,
caustics and HDRI support.
Sampling Control
Sampling control is another feature in Brazil r/s that contributes to both
speed and quality of the rendered image. It has adaptive controls for minimum
and maximum sample ranges. Brazil r/s will look at the minimum sample range
and assign it to areas of the scene that have the least amount of change in
them. In turn, it will go to its maximum sample range for areas that have
a lot of detail and change. This allows Brazil r/s to spend the most amount
of time on the sections of the image that require the most amount of detail.
In a renderer with capabilities that can easily bring a computer to its knees
– this kind of control gives you, as the user, the flexibility to determine
where your quality level needs to be based on when you need the imagery.
Custom Shaders
To complement the renderer, Brazil r/s comes packaged with a number of proprietary
shaders: a standard Brazil r/s shader, a glass shader, a chrome shader, and
a toon shader. Each one is tailored to its specific function to bring out
the best in those materials based on the physical qualities of them. Only
the shader included in the public download is the Standard Brazil shader.
The standard Brazil r/s shader provides more control over the surface than
the standard Max shaders, with channels such as translucency, diffusion to
supplement the diffuse channel, as well as its controls to manipulate the
ray tracing features of the shader.
The material has its local and global controls over the ray tracing, which
give the user the freedom of determining whether or not the actual material
(not just an object) will calculate reflections and refractions. There are
also controls to include and exclude specific objects. Most of these controls
are very similar to the Ray Trace material within Max, so users should be
very comfortable stepping into the Brazil material without climbing a steep
learning curve.
To complement
the renderer, Brazil r/s comes packaged with a number of proprietary shaders:
a standard Brazil r/s shader, a glass shader, a chrome shader, and a toon
shader
Lighting
Finally, and most importantly to a renderer, we come to lighting and light
calculations. Since everything involved with digital imagery has to do with
what we see, and what we see is largely due to how we perceive light and its
reaction to surfaces, the recreation of those reactions is key to making a
renderer work or not. The Brazil r/s team has put a substantial amount of
time and effort into research and development into just these things - light
and how it works.
Global Illumination basically refers to the process of light hitting a surface,
and bouncing to another surface nearby, contributing the illumination of that
second surface. However, when the light does this, it loses some energy. On
the second bounce, it loses more, and so on, until there is no energy left
for another bounce. In CG terms, these are very expensive calculations, and
take a lot of time to get your results. This is still the case in Brazil r/s,
but many parameters are given to the user to determine just how long and
at what quality you will ultimately get. You also have control over which
kinds of lights are contributing to the GI.
Point lights, area lights, skylights, and, in the future, geometry-based
lights, each can be specifically added or removed from both the direct and
indirect light calculations. The GI controls also include controls over the
number of indirect light bounces, exclusive from the bounce controls of the
reflections and refractions of the raytracer.
Sampling control is another feature in Brazil r/s that contributes to both
speed and quality of the rendered image. Click on image to see larger view
Brazil r/s provides photon map-based caustics. Caustics refer to the lighting
effect that you see at the bottom of a swimming pool, or the light patterns
on a table underneath a glass of champagne. This feature is something that
renderers such as Mental Ray have had for quite some time, while others have
developed ways to fake the effect. Brazil r/s has utilized newly developed
technology to allow for a greater degree of control of accurate caustic calculations
to hone the computers efforts to only the math that is needed when the effect
is calculated.
The technology and advancement in photon mapping and how they relate to
caustics is beyond the scope of this article, but for more information you
can visit -- graphics.stanford.edu/~henri/ -- which is the website for Henrik
Wann Jensen, a key researcher in realistic image synthesis.
Similarily, another form of reflection, refraction, photon calculation,
and GI in an amalgam of math and light-based physics is the effect that you
get when you put a flashlight in your mouth and turn it on. Your cheeks light
up red. This is due to an event termed sub-surface scattering, which is when
light photons are scattered within a surface, illuminating that surface from
within or behind. As with the other subsystems, Brazil r/s offers controls
to the user to optimize the functionality. Again, the math behind sub-surface
scattering is beyond this article, but can be found easily within Jensen’s
work.
Brazil r/s provides its own lights. The primary one is an area light, meaning
that light is generated from a surface area, such as a fluorescent light,
rather than from an infinitely small point in space. Area lights are standard
requests for photoreal renders because it give a real sense of soft shadows
and the idea that shadows will get denser the closer they get to the object
casting the shadow. Brazil r/s will include area lights in its final release
with a number of controls for shape, size, and other parameters familiar to
anyone in CG using lights, such as falloff, attenuation, decay, shadow samples,
etc. There are also future plans to create geometry-based lights, which might
be good for items such as neon signs, television screens – basically, situations
where you have an object more complex than a rectangle or sphere emitting
light into a scene.
Another light within Brazil r/s is not actually a physical light in 3D space,
but it contributes greatly to the realism of scenes - especially outdoor scenes.
This is a Sky Light, which is essentially a multitude of light sources generated
on a hemisphere around the scene. The calculations of all these lights, especially
when shadows are also calculated, benefit the scene by softening shadows,
and filling in other shadows, giving a very realistic look similar to, but
not as expensive as global illumination. The skylight generates it hue from
a color selector, but the color and luminance can also be controlled with
a bitmap. So by creating a gradient from orange to dark blue, you could potentially
emulate the look of a sunset. The orange hue would create orange-ish lights
from one side of the scene, while the other side, the night side, would hardly
generate any light at all. You may also use HDR images for your skylight,
which leads us into the another principal feature of Brazil r/s’ utilization
of High-Dynamic Range Imagery.
High-Dynamic Range Imagery--HDRI
Brazil r/s, as mentioned above, will generate HDR images, which have color
ranges beyond the typical 256 colors per channel imagery that most computer
imagery clamps to. Brazil r/s will also use these images to generate lights
sources through the skylights, area lights, point lights, etc. They are also
frequently used as environmental reflection maps. The whole scope of HDRI
is beyond this article on Brazil r/s - quite frankly, everything about Brazil
r/s is beyond this article on Brazil r/s - but in the simplest terms, High
Dynamic Range utilizes imagery that has been generated by taking a number
of images of the same environment at varying degrees of exposure. These images
are combined into one image that retains the color and luminance range from
the shortest exposure time (the darkest) to the longest exposure time (the
brightest).
Why is this important?
The importance lies in the fact that film does not respond to light in a
linear fashion from a value of 0 to a value of 256. When you hit a value of
white in film, the exposure does not stop. Its goes beyond white. The edges
of that area begin to bloom and blur. And as an image darkens, the white
areas do not become shades of gray. More detail begins to emerge in those
areas as the exposure levels drop.
The HDR image retains all that information, regardless of whether you see
it on the screen or not. And this is important in a renderer, because a photo
realistic-renderer must behave as film does to light. And in order to do that,
the information being utilized and the information being generated must go
beyond the limitations of a CRT or LCD monitor, and certainly beyond the
limitations of NTSC.
In Closing
The Brazil r/s interface blends seamlessly into the Max render interface,
and is accessed simply by choosing Brazil r/s as the current renderer. There
are lots of controls and parameters--this is not a "dumbed-down" interface--but
it's still relatively easy-to-use. Brazil r/s handles all Max scenes natively,
and it is compatible with third-party plugins including materials, geometry
deformation, and volumetrics.
The design compatibility between Brazil r/s and Max makes the user feel
at home within the interface, so there is no hunting around for parameters.
The user is less worried about finding the right buttons, and is free to concentrate
of the creative. The ease of use is helped with the fact that the default
parameters are already optimized for high-quality rendering. Within literally
minutes of starting the program, you can build a sphere and a plane, place
a skylight, add a diffuse material to the surface, and render out an image
where shadows are subtly filled and fall off realistically.
Change the plane to a bright red and the sphere to white, and then switch
on the secondary illumination parameters, which activates the GI, and the
image begins to show the red from the floor bleeding into the white of the
sphere. And this is before you’ve tweaked anything. New users will be very
satisfied with how quickly they will get to 80% of what they are looking for.
Experienced users will be happy with the fact that they have enough control
over the image to push the the quailty into that last 20%.
The future of Brazil r/s is quite bright with lots of plans for lots of
new features, not the least of which are RIB compatibility for pipelines
using Renderman, SDK access for developers to write more subsystems, and
portage to Maya and other 3D systems.
The drawback of Brazil r/s, which could
be the drawback to all renderers calculating GI, subsurface scattering, photons
maps, et al., is that the renders can get slow in relation to the Max standard
scanline renderer. But this is the cost of creating photo-realistic imagery.
At this point in time, we have the code, algorithms, and math, we just need
to wait for the hardware to catch up - which will probably be, oh, about
3 days.
For more information, visit www.splutterfish.com
www.trinisica.com
www.neilblevins.com
graphics3.isi.edu/~debevec
graphics.stanford.edu/~henrik
Todd Perry is the visual effects
supervisor and partner at Max Ink Cafe (www.maxinkcafe.com) in Venice, Calif.
Between supervising visual effects and animation for films, television, and
games, he occassionally has a moment or two to impose his thoughts about
the industry on DMN.
source:
www.digitalmedianet.com
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