Build Your Own

Digital Landscape Links and Photo Gallery

Sidebars
The Algorist's Dilemma
L-Systems
Smile, You're on Candid Camera

Digital Landscapes That Fool the Eye

A flooded landscape created in MojoWorld.

With mortgage rates at all time lows, maybe it's time to plow what's
left of your 401k into a little real estate. Or you could load up
Bryce, Vue d'Esprit, or WorldBuilder and roll your own piece of digital
paradise. Since the mid-1990s, dedicated terrain creation programs have
attracted a fan base of hobbyists who use the programs for digital
illustration and fantasy art. Lately, improved speed and rendering
quality have made them viable solutions for digital matte paintings and
movie previsualization, but that's in the short term. Within the next
15 years, as processing power increases, we will see photorealistic
interactive virtual worlds populated by avatars standing in for you and
me. Welcome to the future of entertainment.

We see glimpses of this future in online gaming, while the
underlying technology is developed in world-generation products like
MojoWorld. For Millimeter readers, practical interest in this
software is as a production tool; the world-building visionaries are
focusing on virtual exploration. The difference has been elegantly
summed up by patriarch of world-building Ken Musgrave with the phrase,
“Context not content.”

A rocky MojoWorld setting.

For those of us who labor in the content-oriented camp, our
standards and expectations are dictated at least in part by practical
concerns and our experience with professional 3D software. To some
extent, dedicated landscape generation software applications are scaled
down versions of apps like Maya and 3ds Max offering an optimized tools
set, lots of presets, and ease of use. Users of the heavy iron like
Maya may consider prosumer applications such as Bryce and Vue d'Esprit
beneath them. But these apps suggest something tantalizing: a CGI
future that finally achieves the goal of the digital backlot in which
locations from the Lower East Side to the Sahara Desert are
downloadable databases. That reality may still be a decade or more
away, but the current state of landscape generation gives a pretty good
indication of how future tools will function.

While a prefab world is of interest to production designers and
location finders, digital illustrators are more interested in works of
the imagination. The majority of scenes made by Bryce and WorldBuilder
users are fantasy or sci-fi inspired — but there are also digital
artists who are interested in imagined naturalism. Not only do these
landscape artists avoid actual locations, but some such as Luc Bianca,
who works in France, also adhere to a sort of digital fundamentalism in
which their work is generated entirely in a 3D app. They take pride in
not retouching their work and phrases like “made entirely
in…” often accompany landscape illustrations on digital
illustration web galleries.

Xfrog's trees are "grown" using L-Systems.

This raises the issue of how landscapes are created, and
philosophically what constitutes the artistic process. Historically,
computer graphics have been deeply influenced by the traditional arts.
Photographic texture maps, painted digital scenery, and handmade
elements are an accepted part of a CG artist's arsenal of techniques.
But it is also possible to synthesize surfaces, textures, and all
aspects of the visual field entirely through the manipulation of code.
These procedural methods are the “purest” use of computer
graphics, and as computational power increases it is likely that they
will begin to replace the timesaving visual shortcuts that we depend on
in the visual effects industry.

Which brings us to the reality of making an acre of anyplace.
Ultimately, like all CGI, the only manageable scenes are based on the
classic cheats, namely texture maps rather than geometry, bump maps,
billboards (plant and rock texture maps on clear polygons), cycloramas,
and the rest of the digital illusionist's playbook. This is all
necessary because the world is heavy, man. The scrubby weeds and ground
cover in your backyard replicated in software would require trillions
of polygons, far too many to be computed with today's hardware.

A selection of cacti, also created in Xfrog.

Whether you are using Bryce, Vue d'Esprit, MojoWorld, or Maya, all
landscape generation uses some specific techniques. Mountains and
deserts are essentially displacement maps based on grayscale images or
datasets from national geological surveys (see “Smile, You're on
Candid Camera” sidebar, page 58). Grasses and other simple-shaped
foliage can be generated using particle systems or other efficient
methods of instancing an object, while fractal and noise functions can
be used to generate terrains, skies, and water turbulence. There are
variations of course, but all landscape creation applications rely on
some or all of these core techniques.

As the programs have evolved, many of the landscape generators have
added more sophisticated rendering capabilities, including volumetric
lighting, caustics for underwater scenes, and advanced cloud and
atmospheric algorithms for haze and aerial perspective. At the moment,
only 3D Native's World Construction Set supports High Dynamic Range
Imaging maps, however, many other developers are considering this
feature as well. While dynamics and simulation capabilities are
available in some of the applications, realistic waves and running
streams (fluid dynamics) are yet to come.

Xfrog's detailed sunflower holds up under closeup.

In this article I'll cover the most interesting and relevant
landscape applications for visual effects production including the 3D
apps, Bryce, Vue d'Esprit, Terragen, World Construction Set,
WorldBuilder, and MojoWorld. One caveat: Products that are great for
the hobbyist may not make the grade for Millimeter's audience of
professional visual effects readers. The dividing line between
professional and hobbyist hinges on the axis of animation vs. still
imagery. Almost all the hobbyists' products evaluated can be used for
2D professional concept art and previz, but are less effective for
animation.

Bryce was not the first landscape creation product, but it
popularized the idea of making illustrations procedurally and opened
the area to hobbyists. Corel is the new developer of Bryce, and this
latest version retains the MetaCreation's interface (similar to
Poser's), which is a simplified, non-traditional user interface. CG
artists accustomed to multiple simultaneous scene views, toolbars, and
loads of moveable palettes, however, may find Bryce's dashboard
deployment of tools an inefficient use of screen space.

While Bryce deserves a full review in a magazine for hobbyists, it
is not really designed for the visual effects market. Bryce has
reasonably good procedural terrains and very good sky and water
generation, but its atmospherics are not up to the level of Vue and
Terragen, and its raytracer, while improved, is slow. It recently added
a network renderer, an essential for animation. The newly added Tree
Lab is simply not on the same level as Xfrog, Tree Professional, or
Vue. While good at far and middle distances, Bryce trees are
unacceptable for motion picture visual effects. Bryce is useful as a
previz tool when used in conjunction with Poser and Photoshop for 2D
conceptual art. However, there are competing products that should be
considered first.

At the moment, Vue d'Esprit and Digital Element's WorldBuilder offer
the best combination of ease of use and a complete feature list of the
several landscape generators that are available (World Construction Set
is an interesting runner-up). That means they have realistic landscape,
sky, and botanical capabilities.

Vue d'Esprit's atmospherics and raytracer.("A Day Passes" by artist Stephane Belin.)

A quick look at the images on these pages shows just how photoreal
the results in Vue d'Esprit can be. Available for Windows and Mac (OS X
only), Vue d'Esprit 4 is a pleasure to use. It is clearly a high-end
hobbyists' tool with enough horsepower to be of use in professional
production for boutiques and lone wolf CG artists.

Vue d’Esprit offers realistic landscape and botanical capabilities. (Artist: Norbert Garaj.)

Vue is essentially an advanced version of Bryce. While Bryce 5 has
some nice features of its own, including a sky dome with properly
positioned stars, Vue will yield more photorealistic scenes and its
foliage is far superior. In Vue d'Esprit you begin the creation process
by selecting an atmosphere from the preset palette, which features
picons of atmospheres. You can modify these or create your own. An
atmosphere defines the sun's position, the sky (including clouds and
haze), and ambient light. You can change the individual parameters in
the atmosphere palette and move the sun to change the time of day.
Terrains, rocks, planets, and foliage are then added to the scene, and
Vue smartly provides layers for these additional objects. This is
essential for managing hundreds of objects.

Even after you have set up a complicated landscape, you can quickly
select a new atmosphere from the presets and it replaces the existing
one. This completely changes the mood of the scene. The lighting and
atmospheric model in Vue are realistic over a wide range of sun
positions for any atmosphere once you have made the global adjustment
to the sun's brightness. (Fast results are why artists without 3D
experience are attracted to landscape software.) Vue also provides a
library of procedural textures including metals, rocks, liquids,
clouds, animated materials, wood, landscapes, glowing, and many others.
Every material can be edited and combined with other materials. Every
parameter of a material can be keyframed for animation.

Vue d’Esprit provides layers for managing a number of objects.

One of the main strengths of Vue is the library of SolidGrowth
foliage. Vue's trees and plants are the most sophisticated available in
a general purpose landscape generator. At close range or at a distance
they are extremely convincing. There is a scatter-and-deploy feature
that randomly distributes plants or trees over a terrain, and because
the plants are procedural, each of them is unique. The library contains
about 25 plant types, and there are a few others available at the Vue
d'Esprit website. However, it would be great to see even more
variety.

Vue d'Esprit provides a number of primitive objects for making
organic and man-made structures, or you can import models in DXF, OBJ,
3DS, LWO, COB (TrueSpace), and PZ3 (Poser4). The MOVER module
(purchased separately) allows Poser animations to be imported with
materials supported. The product lacks dynamics or a particle system,
so falling leaves or wind effects are not possible within the program
at this time.

Each Xfrog cactus is unique.

Animation has recently been added to Vue d'Esprit and like Bryce,
the tools are rudimentary although the basic layout is a good start. A
standard horizontal timeline with a dropdown list of objects and object
properties on the left-hand side is familiar interface territory, but
there are a few issues that need to be addressed. The function curves
are limited, and there is only one type of keyframe. The curves are
also not displayed on the timeline and can only affect the
interpolation between the first and last keyframes in a sequence of
keyframes.

There are a few other interface quirks, including the confusing
render window — your render settings are the same as your preview
settings, requiring reopening the render window to reset the output
settings when you return to working on a project.

All in all, this is great software with tremendous depth in a
relatively simple interface. A dose of professional input for the
animation controls and the render queue would be a big step forward. If
Vue was able to import and export camera data to mainstream animation
software, then this hobbyists' tool would have a place in film and
television production.

Xfrog by Greenworks has a well-deserved reputation for being the
most sophisticated of the various organic model generators. I have
created and imported several of their trees into 3ds Max, and when
properly lit, they will absolutely fool the eye. Like Vue's
SolidGrowth2, Xfrog “grows” organic models using what is
generally known as an L-System (see “L-Systems” sidebar,
page 56), which employs algorithms to imitate the natural growth
process of living things. Every tree and plant generated in an L-System
is unique, and the detail of finished and texture-mapped plants hold up
to inspection even in closeups. Xfrog is not restricted to foliage and
can also generate beautiful organic abstract models.

Which plant is real?

Xfrog is Windows-based and, along with Onyx Tree Professional, is
the greenhouse of choice for visual effects companies. Greenworks
offers four products based on their L-System technology: The main
program, Xfrog, is a 3D organic modeler that is capable of generating
trees, flowers, plants, organic-iterative architecture, and abstract
structures. XfrogPlants is their library of trees available in 15 sets
providing a total of 900 models developed by botanical experts.
XfrogTune is a polygon-reduction product that helps reduce the data
load problems that are inevitable when using realistic trees and plants
in a 3D application. XfrogMLOD is a realtime solution offering
multilevel-of-detail trees for gaming and interactive environments.

Xfrog supports Maya, 3ds Max, Softimage, Lightwave, Houdini,
Animation Master, Cinema 4D, Poser, Vue d'Esprit, WorldBuilder, and
World Construction Set; renderers include Arnold, Brazil, Pixar
RenderMan, and finalRender.

A landscape created in Terragen by Luc Bianca.

Building algorithmic models in Xfrog is an additive process, and
appropriately you build a plant from the ground or, at least, the
component up. There are three component types: components that create
objects (horn, tree, simple, and leaf); components that multiply
(wreath, phiball, revo, and hydra); and components that edit
(attractors and hypercubes).

You begin by selecting a component and assigning values, and link
these to other components in a hierarchical structure. A component is
an algorithmic instruction of objects found in nature and in that sense
provides a mathematical destiny rather than a fixed description. That
is why L-Systems are an ideal way to generate plants since they are
actually intended to mimic cellular growth in increasingly complex
arrangements. That said, making trees or fantastic organic designs is
not automatic. The learning curve is several afternoons before the
process begins to make sense. L-Systems produce excellent results but
are by definition an experimental process: If you approach Xfrog as an
illustrator or traditional model maker and expect to make a specific
design of a tree, you will be frustrated. Fortunately there are
pre-made models and these are available with their structure intact so
you can apply component editing to an existing plant or tree. You could
also buy library models and use them for your 3D scenes without ever
resorting to original designs.

A scene from The Cider House Rules, finished in World Construction Set. (Eye Candy lead artist Al Magliochetti.)

But wait, we are still in the world of 3D cheats, and the surface
details of Xfrog models are all texture maps. These are handled with a
great deal of control, but you will be back to making bitmaps in
Photoshop and putting mint leaves on your scanner. You'll be happy to
know that all Xfrog models come with the appropriate texture maps.

Greenworks, located in Germany, is a very supportive company. They
have a well-organized site and downloadable import plug-ins, tutorials,
and notes are all clear and answered most of my questions. This is the
Rolls-Royce of botanical modelers.

This stalwart botanical modeler is a close competitor to Xfrog, but
takes a different approach to model making. Tree Professional comes
with 260 ready-made trees that are fully editable. You can also model a
tree from the ground up (there is no other way to say that). You
actually begin with a random seed to start the trunk, and there are
parameters such as trunk height, bottom height, crown center, bough
length, length change, bough angle, bough density, bough curving, etc.
Branch curving alone has half a dozen parameters. The process is
straightforward and the results are highly realistic. You can even use
the chain saw tool to cut branches or to slice through the trunk.
Leaves are image maps on a polygon plane called a plate.

The latest version has added trunks with visible roots, bonsai
curved branches, and a DFX block structure that lets the user globally
apply any texture to all the leaves in a tree. Tree Pro also supplies a
leaf texture CD with the software for the trees in the library. In
early 2003, wind dynamics was added.

Since Tree Pro is strictly a modeling program Onyx has done a good
job of supporting all the major output file types for host
applications. There is also considerable control on the export
parameters so you can decide the level of detail in your finished
tree.

Unlike Xfrog, Tree Professional lets you determine the specific
shape and limb arrangement of a tree. This is useful if you have need
for a very specific “hero” tree. If you need a realistic
forest, the pre-modeled trees are just fine. Tree Professional has
output that is comparable to Xfrog, but it only makes trees; Xfrog has
a greater variety of trees, and also generates grasses, vines, flowers,
shrubs, and ferns. The advantage of Tree Professional is the ability to
design specifically shaped trees using an artist-friendly
interface.

The original Animatek WorldBuilder was the first really ambitious
landscape generator I encountered in the mid-1990s. The animations
created in WB showed fields of long grasses, dozens of trees, and
flowing water. Scenes of this complexity should have brought a PC to
its knees in 1996, and despite some noisy aliasing, WB was showing its
ambition of creating software to build lushly foliated worlds.

From its very beginning, WorldBuilder has had a close relationship
with 3ds Max and the interface remains very Max-like. They have also
developed the most balanced landscape toolset including L-System trees,
procedural terrain, sky, atmosphere, water, integrated dynamics for
wind, and particle systems for rain and snow. At the moment,
WorldBuilder and Terragen are the only products that are aimed at the
individual professional animator and the desktop visual effects
markets.

WorldBuilder has been developing this tool for seven years and they
are being modest by calling this a 3.0 version. WB offers procedural
solutions for all aspects of landscape creation as well as the widest
range of 2D cheats. There are also numerous innovations beginning with
skeleton lines (a method of drawing a profile for a terrain that is
similar to lofting). This is a more direct modeling technique than
painting a grayscale map or image-editing a DEM in Photoshop. However,
skeleton lines can be combined with other methods of terrain creation
as well. Splines are also used as a way to place texture maps in
discrete areas of terrain. That means a small area of a mountain or
cliff side can be assigned a texture, shader, or a patch of grass that
is contained within the spline-defined area.

The vegetation in WorldBuilder is procedural and includes a CD
library of trees, plants, and grasses and a complete L-System for
creating user-designed foliage or editing library models. Like other
aspects of the program, 2D solutions supplement the full 3D models, and
tools for making flipboards mapped with trees are built into the
workflow. Another area that offers 3D and 2D solutions is clouds. There
are several options including full volumetric clouds, procedural 2D
clouds, and combinations of the two on layers.

The water simulation capabilities are unique within the landscape
creation arena, and WB offers dynamics that allow a leaf to float on
the surface of water and float down a stream. As for matte painting,
WorldBuilder's renderer has a painterly, illustrated look that is
naturalistic, but not as purely photographic as Vue d'Esprit or
Terragen. In fact, WB is the only landscape product listed here that
does not employ a raytracer. Depending on the environment, an artist
can push WorldBuilder to match seamlessly with a film backplate,
however, WB's renderer tends toward a particular softness.

This remarkable shareware program has a loyal following of artists
around the world. Currently available for Windows and OS X, the product
is capable of very nearly photographic results. Developers Matt
Fairclough of Digital Domain and his partners hope to release a fully
productized version within two years. This is the first landscape
generator written by a visual effects artist working at one of the
premiere houses. Fairclough has suggested that there may be a light
version for hobbyists, but it is clear that this work in progress is
destined to become a serious production tool.

Currently, Terragen offers terrain, cloud, and water procedurals,
with add-on scripts for animation, camera control, texture mapping
tools, etc. You really have to visit the site (www.planetside.co.uk) to learn the latest news. The
next major feature is support for Xfrog plants and trees. Edging out
Vue d'Esprit, Terragen has the most convincing atmosphere models, as
the work of Luc Bianca will attest.

The interface is remarkably simple, partly because the product has a
limited feature set, but you can turn out a landscape within a few
minutes of opening up the program. This was a refreshing discovery
since I half expected a product designed at DD to be one step removed
from command line code. That's definitely not the case, and there is a
very good tutorial to get you started.

Let me begin with the advice that anyone interested in computer
graphics technology and its application to the imagination should
really get ahold of this product. MojoWorld is as much a vision, dream,
and concept of the entertainment future as it is a landscape generation
application. Reading the wonderfully designed manual and beginning to
play with the possibilities of the software reminded me of a more naive
time in computer graphics less than 10 years ago, when dreamers and
visionaries could defy the marketplace and create software just to do
great things. Ken Musgrave, the current dean of landscape creation and
the man behind this far-reaching project, is keeping that spirit alive
in MojoWorld.

Millimeter will tackle this product in-depth in a future
review, but here are the basics: Musgrave is passionately interested in
realtime environments and procedural landscape art rather than
production tools for the motion picture industry. MojoWorld is more
than just one product: MojoWorld Generator 2.0 and MojoWorld
Transporter (also in a Pro version). Transporter is an exploration tool
that lets you travel in universes that you download. You can render
these worlds and make some global changes, but you cannot create
planets or terrains. Transporter is aimed at the community of MW users
so they can share their experiences.

Generator 2.0 is the beef. It's entirely procedural, so the files
are absurdly small. You can fit several densely complex worlds and
their moons on a floppy with room to spare. The texture generator is
the most advanced I've seen, and the atmospheres are very good. The
interface is non-traditional and may take some getting used to, but
overall the workflow is intelligent and generally fun. And image
quality is superb.

Currently in Version 2.0, the experiment is in an early stage of
development — it's clear that Musgrave's vision requires 1000
times more processing power. The dream here is a deeply imagined
“inhabitable” cyberspace. If that future is not quite here,
at least MojoWorld gives us a great travel brochure.

One of the oldest dedicated landscape generators, WCS began on the
Amiga as a tool for city planners, geologists, architects, and civil
engineers. WCS specializes in modeling real locations because that's
what the majority of their users do. The product has added a powerful
feature set over the years and clearly worked hard on their image
quality, but this is not a product that had any initial interest in
motion picture production. Many of the conventions and UI are going to
flummox traditional 3D animators on Windows or the Mac version, but WCS
makes the extra effort to learn the program worthwhile. While WCS would
not be my first or even second choice for rendering realistic terrains,
this software is outstanding for site planning for movies, exterior set
design, and general previsualization.

Here's why: Almost every landscape creation product can import
United States Geological Survey data (mainly digital elevation models
— DEMS), however, there are several flavors and file formats, and
WCS has a wizard to make this easy. The founder is a geologist, so tech
support has expertise in the agencies, products, and providers of USGS
materials. WCS goes beyond creating heightfields from DEMs for chunks
of territory — the product understands that any DEM is a location
on the planet and can place your landscape at the right longitude and
latitude on a spherically accurate representation of the earth (whole
earth data comes with the program). This makes possible one of the
cooler features, which is the ability to click on any part of a terrain
in a perspective view and find the distance from the camera as well as
the exact longitude and latitude.

In addition to DEMs, WCS can import satellite photos and aerial
photography. When coordinates are supplied with the image, it can be
automatically lined up with a DEM-generated terrain.

Because ecosystems, forestry, parks, and landscape architecture are
critical aspects of the kind of work the majority of WCS users do, the
product is particularly good at understanding accurate representations
of local flora for a given area. The community of WCS users is an
excellent source of information and expertise for moviemakers who need
specific data about a location and a way to experiment with sets and
camera angles before visiting the site.

WCS has an up-to-date feature set including volumetric clouds,
volumetric atmospheres, procedural textures and terrains, depth of
field, motion blur, and a tree library (2D only) that emphasizes large
data sets over photorealism. WCS flat trees are very fast to render and
respond interactively to volumetrics and light.

This is the application to buy for real world location planning and
site previsualization.

Are procedural landscapes the end of handmade art? Well, no more
than photography replaced painting, which was a widespread fear in the
19th century. Still, photography has become a major tool for painters
and illustrators with optical devices being used as early as the
Renaissance. A tour around the Poser, Vue, and Terragen web rings is a
surprising introduction to a groundswell of amateur, self-instructed
digital illustrators. Just five years ago it was extremely difficult to
find anything but tacky, poorly crafted illustration, and this is no
longer the case. The computer has democratized art on the Internet and
created an open-source community of artists who share and comment on
each other's art in an encouraging and cooperative spirit.

Simultaneously, the creation of realtime worlds points to the
evolution of narrative art or at least the spatial conditions under
which we are encouraged to suspend belief. The technology is here for
both matte paintings and online exploration. This is manifest destiny
set in cyberspace without the displacement of indigenous cultures. No
guilt and lots of fun.

THE ALGORIST'S DILEMMA

It all began in the 1970s with mathematician Benoit Mandlebrot, the
father of fractals. The leap from math to terrain was made when he
realized that certain mathematical functions generated lines that
resembled mountain peaks. Mandelbrot became fascinated with the idea of
creating worlds based on procedural methods including atmospheres,
bodies of water, and planets.

In the 1980s Ken Musgrave was accepted into Mandelbrot's fold at
Yale as his computer programmer. Musgrave, who started college as an
art student and ended up with a doctorate in computer science, became
hooked on digital landscape creation and has made it his life's work
and art. Generally considered the premiere expert in the field,
Musgrave was on the team that created Bryce and is now the man behind
MojoWorld.

While fractals are borne of mathematics and share certain
similarities to the things they are used to imitate, they are
essentially a counterfeit of nature. In other words, while artists who
use computer algorithms to create art (some have given to calling
themselves algorists) may disparage the use of bitmapped photographic
or painted textures in landscape creation, physicists are similarly
unimpressed with the algorist's fractal methods. That's because the
fractal generation of natural objects does not take into account
physical or dynamic processes. Erosion and water turbulence in a
procedural landscape are usually illusions based on noise functions,
not gravity, friction, or fluid dynamics. Most of the time, fractal
landscapes are more illusion than physics.

L-SYSTEMS

Introduced in 1968 by biologist Aristid Lindenmayer and bearing one
letter of her surname, L-Systems use algorithms to formally describe
the development of multicellular organisms. This mathematical imitation
of plant development is ideally suited to modeling branching structures
whose interconnected parts change in number dynamically — in
other words, foliage. But we can go back to 1904 to find the origin of
the earliest L-System, thanks to Helge von Koch, a mathematician who
wrote a formula that when reiterated, could generate what is called the
Koch snowflake or Koch island.

Look familiar? Like a fractal perhaps? An L-System is based on
fractal math. As you know, 3D software programs have been using
fractals to generate landscapes and other organic forms throughout the
history of computer graphics. L-Systems are based on the concept of
rewriting. Rewriting defines complex objects (like trees) by
successively replacing parts of a first basic object called an axiom.
Rewriting rules are called productions. The process begins when
production rules are applied to the axiom — this is called a
string. Subsequent strings are generated by using the initial string as
the input.

One result of this process of reiteration is that the strings grow
in length. More importantly, the growth and the patterns it yields
continue to exhibit characteristics of the original string while
yielding new patterns. These last two sentences describe the L-System
and in a visual sense, the growth and development of a dandelion. This
process is called morphogenesis. All of this will be on the final.

The value of an L-System is that it is a mathematical model for
organic growth. This is great for CG artists because it allows a plant
to be animated from seed to blossom. At the same time, by strategically
introducing randomness into an L-System, plants of the same type can
have subtle variations while preserving an accurate botanical
description of the plant.

Interested in more of Lindenmayer's work? Read The Algorithmic
Beauty of Plants by Przemyslaw Prusinkiewicz and Lindenmayer.

SMILE, YOU'RE ON CANDID CAMERA

Yes, we are being watched and tabulated. The surface of the earth is
the subject of spy photos, weather maps, and geological surveys and is
calibrated according to the 24 orbiting satellites that make GPS
(global positioning system) possible.

All this watching is bad news for privacy and good news for
landscape generation. The entire surface of the earth has been
recorded, and it's available online and much of the data is free.

The United States Geological Survey (USGS) is the sole science
agency for the Department of the Interior. Their role is largely
fact-finding, and this leads to a lot of maps and mapping of the U.S.,
as well as other parts of world including the oceans. Much of the data
is sold by business partners of the USGS.

If you need to crash an asteroid into the San Francisco Bay and want
to model that area, you could buy satellite photos and topographical
maps, but DEM data is what you need for digital terrain creation. A DEM
is a digital elevation model and it's a representation of the topology
of the earth in raster form. It's the common format used by every
landscape generation software. DEM data is available on the USGS
website for all of the U.S. There is also similar data for Mars (DTM)
and Venus (GTDR) available from NASA's Planetary Data System (PDS). All
this data can be downloaded or purchased as CD-ROMs.

The USGS has a cool site that lets you quickly select a map for any
area in the United States (http://edcftp.cr.usgs.gov/glis/hyper/
guide/1_dgr_demfig/index1m.html). The maps are quite large, and the
resolution varies depending on the region. Many DEMS use a 30-minute
grid. In other words, the area covered is divided into 30-minute
squares, with one minute at the equator equal to approximately 1.15
miles. No detail smaller than that will show up. However, there are
DEMS that are as small as 7.5 minutes, or about 500 yards. Most of the
landscape generators permit using fractals to displace a DEM-generated
terrain to apply greater local detail.