4.2.1 Paraline/Orthographic Drawings
4.2.2 Hypsography
4.3.1 Surfaces
4.3.1.1 Flat Planes
4.3.1.2 Rippled Surfaces
4.3.1.3 Lakes and Ponds4.3.2 Solid Representations
4.3.2.1 Simple Parametric Solids - Prisms
4.3.2.2 Falling Water
4.3.2.3 Spray, Mist, Drops
4.4.1 Simple Color
4.4.1.1 Transparency
4.4.1.2 Reflectivity
4.4.1.3 Refractivity4.4.2 Multichannel Textures
4.4.3 Underwater Effects
4.4.4 Wet objects
4.4.5 Puddles
4.4.6 Snow and Ice
4.6.1 Movement Through Water
4.6.2 Movement of Water4.6.2.1 Ripples and Waves
4.6.2.2 Waterfalls
4.6.2.3 Fountains4.6.3 Multimedia - Sound
Figure 4.2 Water as a. a flat blue plane, and b. a rippled surface.
Figure 4.4 Transparent solid volumes of "water": cylindrical, rectangular, and hemispherical.
Figure 4.6 A two-tiered fountain with rivulets of water created using particle systems.
Figure 4.10 A fountain and reflecting pool at the moorish gardens at the Alhambra, Spain.
Figure 4.16 a. A forested hillside covered in snow. b. Tree branches covered in snow.
Figure 4.20 Simulated Flooding of the Williamette River in Oregon
Figure 4.25 Model of a fountain with water falling from a channel in a brick wall into a basin.
Figure 4.26 Detail of a sound file displayed in sound-editing software.
Water, even when unseen in the landscape, is everywhere, and all-important. Water is never alone in the landscape; it is held and shaped by landform, which is revealed at the edges, banks, and beaches. Vegetation depends upon the workings of the hydrologic cycle, as water moves through the landscape, often underground, and through the atmosphere, giving rise to weather and atmospheric effects including snow, fog, rainbows, and others. Water is sometimes still as glass, placidly reflecting the sky and landscape around it, sometimes barely rippling, giving sparkling glints of reflected sunlight to the scene, sometimes turbulent and tumultuous, as at the beach in a storm, or at the base of a waterfall.
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The many forms and properties of water present special challenges to digital modelers. In its most simplified forms, water may be simulated as reflective glass, haze simulated by a progressive lightening and blueing of landscape colors in the distance, and rainbows painted in; but in its more dynamic forms, rippling and forming waves on ponds and lakes, sparkling, splashing waterfalls and fountains, pouring rain and thunderstorms, water requires complex motion control and particle systems.
Water, having no real edges or fixed shape, is hard to represent in a 2D line drawing. Typically, it is only indicated by its effects, such as a shoreline, or surface features such as ripples or waves. Plans and sections may have indications of water's edge, or elevation.
Just as terrain (topography) is most simply modeled in 2D by the use of contour lines, water is also described by contours of the underwater basin, or hypsography. These contours only represent the shape of the underwater surface, and not the water's elevation, which is naturally slowly changing over time, due to rainfall and evaporation. (Typically, water's elevation is given as an average, or mean, as in the case of the average value for the ocean's water, mean sea level, or MSL, a value taken between high and low tides, and averaged over several seasons, or even years.)
Figure 4.1 From the original plan for the "Improvements to the Muddy River", part of Boston's "Emerald Necklace" by Frederick Law Olmsted. These hypsographic contour lines in the bodies of water are really more cartographic symbols than accurate indicators of sub-surface elevation.
In 3D, although water has volume which is important to its visual appearance, it's usually the surface characteristics that are most readily modeled. Starting with a simple flat plane and adding ripples and waves when appropriate, water can be represented most effectively with surface characteristics.
Water has three important physical and optical characteristics which give it much of its appearance in the landscape: it's in varying proportions transparent, refractive, and reflective. Often defined as a clear liquid, water in the landscape primarily takes its color from its surroundings (except when it has other materials - sediment, dye, algae - providing coloration). Blue water is mostly blue from the sky, although, of course, minerals and other underwater conditions add a variety of colorations to water.
Water's liquid surface gives rise to surface irregularities under the slightest effect of wind or other disturbance. These irregularities are most often waves and ripples which have a simple underlying mathematical structure, overlaid with random "noise."
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Figure 4.2 Water as a. a flat blue plane, and b. a
rippled surface.
Large areas of water, such as lakes and ponds, harbors and marinas, are contained and defined by the landform that surrounds them. (The edge of water is the best example of a "real" contour line!) A model of such waterbodies can be made by creating a detailed terrain model, with contours describing the basin in which the water sits (hypsography), and then placing a simple flat plane or surface of water at the correct elevation. The hidden underground areas of the water surface will be invisible when rendered, and the water's edge will be perfectly described by the intersection of the terrain surface with the water surface. One advantage of this technique is that the water elevation can be easily varied, and can even be animated over time to illustrate, for example, the tidal flux in a marine basin. Often a special surface texture or covering should be used right at the water's edge (sand and gravel, or rocks, e.g.), and should be applied in a band at the correct elevation range, especially if the water's elevation will be varied.
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Figure 4.3 a. Terrain model with blue water surface
below it; Water surface elevation is raised above normal, showing flood condition.
Using multiple layered surfaces is an effective way of generating depth in water features, but water may also be modeled as a solid volume. This is necessary, for example, to take advantage of refraction in rendering the water volume.
The simplest volumetric/solid form for water is just the solid created by the water-containing shape, a rectangular prism, or cylinder, or half-sphere, etc. When modeling a pool or fountain, this is usually adequate. Often, you can benefit from adding an additional surface layer above the solid volume. Rippling waves are often better implemented on a mesh surface than on a solid.
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Figure 4.4 Transparent solid volumes of "water": cylindrical, rectangular, and hemispherical.
Falling water takes on organic, twisted, irregular forms under the force of gravity, wind, and the effects of surface tension. Modeling these forms is similar to modeling tree trunks and requires the use of twisting, braiding, and other curvilinear distortions. Often, a lofted surface along a smoothly curved arc trajectory is a good beginning. Then some organic deformations, such as twisting, or smooth bumps and swellings, can be added. Getting realistic water forms is difficult, due to the fluid and dynamic nature of real water, but coupled with appropriate textures using color and transparency, and using other visual cues such as structures and containers, the visual effect can be convincing. More effective falling water may be accomplished using particle systems to create a stream of "objects". For most effective modeling of falling water, using animation coupled with sound is required.
Figure 4.5 Images of solid water forms: sheets, cylinders, jets, drops created with solid modeling primitives and warping modifiers such as twisting and tapering.
Figure 4.6 A two-tiered fountain with rivulets of water created using particle systems.
When falling or moving water breaks up further into droplets, spray, and foam, particle systems may be the best approach for generating appropriate images. A photographic image map of bubbles or foam might serve for a static image, to be carefully hand applied. Foam is usually best modeled as a texture map on an irregularly shaped blob, set floating on water.
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Figure 4.7 Images of particle systems: a. Four diferent
particle emitters: a rectangular area, a solid line, a point, and a cone. The
simple particle streams they emit are like water falling straight down under
the influence of gravity. b. Particle "warpping" and "deflection": particles
lifted up, as if by a current of air, or a swarm of bees; particles shooting
straight out and falling under the influence of gravity; bouncing off a reflective
plane; and piling up on and around a spherical defllector.
Click here for the Animation of Particles.
Since its physical shape and geometry are so elusive, water's presence in the landscape is mostly conveyed by textures - color, sparkles, reflections- as well as by its secondary effects (depressions in landform and changes in vegetation, e.g.)
Although water as a chemical element is colorless, water in the landscape may well have an inherent color, due to minerals, sediments, and other impurities as well as surrounding landscape conditions. Blue or green hues are common, but so too are brown, depending on whether the water body is the Caribbean sea (many shades of azure), or the Mississippi River (mostly shades of ochre and brown). Lighting conditions, including both the environmental lights (sun, sky, and moon) and artificial lights - including those placed in and under water for effect - have a big impact on the look and color of water. When the digital modeling task is not a literal representation, the choice of water color may also be determined by desired mood and atmosphere, ranging from cheerful and playful to somber and menacing.
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Figure 4.8 A pool of water at Hamilton Springs, outside of Austin, Texas. The blue and green colors are variegated by shadows, reflections, depth and surface ripples.
All water is to some degree transparent, permitting light to pass through it, enabling the viewer to see into it to the surface and objects below. In a well-maintained aquarium, the water truly becomes a clear medium, revealed only by the motion of fish and seaweed within. Water in the landscape has a limit to its transparency. Even the crystal waters of the sea, sometimes permitting vision as much as 10 meters or more below, has a measurable "cloudiness," measured by scientists as turbidity. This gives a diminishing transparency with distance, as with other transparent materials including glass.
Figure 4.9 Water surfaces over a textured pebble surface,
at varying degrees of transparency: a. 10% b. 90%
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Technical note In rendering, transparency of materials is often expressed as a parameter varying from zero to one (or from 0 to 255 in an 8-bit data representation), with 0.0 (or 0) being completely transparent and 1.0 (or 255) being completely opaque. This value (often carried in a transparency mask, or alpha channel) is really descriptive of the transparency at a pixel level: a transparent pixel will not obscure an underlying one at all, an opaque one will completely block the underlying, and a 50% transparent one will permit the underlying pixels to be seen through the top one, in some manner (averaging brightness and color values, for example). |
In addition to transparency, water also has a degree of reflectivity, perhaps its most striking characteristic in the landscape, especially when viewed at a distance. Light rays striking the water's surface both penetrate it transparently, subject to the refraction and diminution with distance, and are reflected at an opposite angle (in simple reflection, "the angle if reflection is equal and opposite to the angle of incidence"). The proportion of the light that is reflected from water is a function of the angle of incidence (light striking perpendicularly is mostly absorbed, light striking at an oblique angle is mostly reflected). When water is perfectly smooth, it may appear much like a glass mirror. Usually though, water has surface ripples which give rise to interrupted and irregular reflections, with highlights which appear as sparkles.
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Figure 4.10 A fountain and reflecting pool at the moorish gardens at the Alhambra, Spain.
The channel of water in the ground represents heaven, and appropriately reflects the sky.
Refraction is the physical property of bending light rays, due to varying density of the material the light passes through. In a controlled fashion, using curved surfaces of glass or water, refraction is the basis of every lens, enabling magnification and concentration (focus). In a more simple fashion, through a prism, refraction bends different frequencies of visible light by different amounts, giving rise to rainbows and other appearances of spectra. In water, light waves refract as they pass from air into water, giving rise to the appearance of displacement of objects underwater, sometimes accompanied by slight magnification. In the case of a straight pole immersed into still water, the pole will appear bent at an angle of a few degrees.
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Figure 4.11 a. Diagram of angles of reflection (above) and refraction (below). b. Illustration of the effects of reflection and refraction as a pole passes through a volume of "water". Notice the extra (unrealistic) reflection on the bottom face of the cylinder, an artifact caused by the renderer used to produce this image in 3DStudioMax.
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Technical Note Reflection and refraction both give visual effects as a result of the angle of a beam of light; in the case of reflection, as it strikes a reflective surface; in the case of refraction, as it passes from one medium (usually air) into another (such as water). For reflection, the rule is simple: a-i = a-r, or angle of incidence = angle of reflection. When there are surface irregularities (e.g. the surface is not perfectly flat) there may be scattering that results giving rise to specular highlights and sparkling, when all or most of the light is reflected back in a single direction; or diffuse reflection, when the light beam is scattered into all or many directions. Many rendering systems give fine control over the specular as well as the diffuse component of reflective surfaces. In the case of refraction, the equation is a bit more complex: n1 sin a1 = n2 sin a2 (Snell's Law) where n1 and n2 are the refraction index of the first and second medium, and a1 and a2 are the angles of the light beam (from the normal) in the first and second medium. The index of refraction is related to the speed of light in the medium, so for a vacuum it is 1.0, for air it is 1.00029, for water at 20¡ C it is 1.33, and for glass, around 1.5 |
The combination of color, transparency, refractivity, and surface texture makes modeling water a complex task. Combining multiple layers with various levels of transparency and colors is a good beginning. Often, in real water, with a shallow bank, colors are gradated from transparent, revealing underwater stones, sand, and gravel at the shallowest part, to pale blues and greens with less underwater detail visible, to darkest blues and greens (or browns, or black, depending on the lighting and water condition) with no subsurface detail visible at the deepest. This can be modeled by three layered surfaces, each with color and transparency, and possibly an image map at the bottom.
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Figure 4.12 Photographic texture maps used for foliage
at water's edge and and pebbles in a stream bed. a. Perspective view showing
tilted plane of the ground surface embedded in volume of water, texture maps
applied for foliage and pebbles. b. Final rendering of water and pebbles at
stream edge.
The landscape underwater (aquascape) is visually determined mostly by lighting conditions. Three special effects dominate: color, murkiness, and light rays. The characteristic colors of underwater range from bright blue to muddy brown, with corresponding varieties in murkiness. Murkiness can be modeled as very strong atmospheric haze (see Chapter 5).
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Figure 4.13 a. Images of caustic light patterns. b.Underwater
scene with "God rays" in ocean water; caustics on top surface of whales. Courtesy
of Rodney Hoinkes, Immersion Studios Inc.
Water occurs not only on its own in the landscape, but it can color and change other elements. Wet objects have a combination of shininess or slickness in appearance, as well as often a physical change in shape as well (drooping under gravity from the added weight of the water, for example, and with sharp edges softened, as with wet fabric). Water also tends to darken colors of materials such as paving. Since water evaporates, and is fluid to begin with, the outlines of wetness are usually irregular and patchy. Wet surfaces are best modeled with a combination of color, shininess, and photographic texture.
Puddles occur in the landscape as a result of irregularities and depressions in the terrain. Even the most carefully leveled paved parking area has small, local imperfections, and water finds and highlights them, from its tendency to run to lower elevations, and to "seek its own level," forming small local perfectly flat areas which contrast with the surrounding terrain. On brick, asphalt, or concrete, often these puddles, over time, form a kind of "bathtub ring" of stain or discoloration that extends around the perimeter of the puddle. Modeling puddles can be done in the same way as described for lakes and ponds earlier: a flat surface of water is superimposed over the slightly irregular terrain of bricks or paving. Where the water is exposed is the puddle.
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Figure 4.14 Puddles simulated by an undulating water surface overlaid on a flat paving surface. Modeled and rendered in 3DStudio Max.
Water in its frozen form - as snow or ice - can cover and transform the landscape, at least in temperate and colder climates. In its simplest form, snow covering is just a whitish surface on terrain, with various colorations, textures, and reflective qualities. Frozen water, such as ice on a lake or pond, may take on a variety of colors and textures, from shiny transparent black ice to matte white or dull gray. Often, entrapped air and other impurities cause ice to become cloudy and opaque, but because it retains some of the water's transparency, refractivity and reflectivity, it can have a wide range of visual appearance.
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Figure 4.15 a. A field of snow, on rolling terrain,
with bright direct lighting to match the background sky image. b. Ice "cubes"
on an icy surface. Modeled and rendered in 3DStudioMax.
Figure 4.16 a. A forested hillside covered in snow.
b. Tree branches covered in snow. Modeled and rendered in Blueberry3D. Courtesy
of A. Ogren, Blueberry3D.
At the scale of the larger region, you can use GIS data and software to create representations of water in the landscape. In addition to digital elevation models (DEMs) from the USGS, you can obtain hydrologic features maps, which show streams, rivers, and lakes in vector format (lines and polygons). You can use these maps, along with other features such as vegetation, or aerial photography, to create a geospecific texture map, with enhanced blue colors for water, to drape over the terrain. You may have to widen the streams and rivers to have them show up, depending on the scale and the angle, amount of vegetation, and other factors in the visualization.
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Figure 4.17 a. Streams and lake show as blue in landcover
GIS map. b. The water level in the lake is artificially elevated by inserting
a flat blue plane at a new higher level in the 3D perspective view, to visualize
the effect of raised water level.
Figure 4.18 Images from GIS study of the effects of
regional growth plans on subsurface water supplies in the region of the San
Pedro river, Arizona. a. Aerial view of development pattern. b. False color
view showing subsurface water levels, dropping due to aquifer depletion from
water supply wells. Modeled in ArcInfo and rendered in World Construction Set.
Courtesy of Michael and Tereza Flaxman, Carl Steinitz, et al, Harvard University
Design School.
Beyond its visual characteristics, perhaps the most important characteristic of water is its fluidity, which enables it to flow and to alter its surface form in myriad ways, from mirror flat to rippling waves to roiling turbulence, and to change its form from ice to steam. These dynamics are of course impossible to truly represent in still images or solid geometric models. There are, however, some basic techniques for starting to model the forms characteristic of moving water, including waves, ripples, bubbles, streams, so that elements such as fountains and waterfalls can be introduced into your landscape model.
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Figure 4.19 Images of physics-based water simulations,
in which water splashes and waves are simulated as multiple tiny droplets interacting
according to the laws of physics and hydrodynamics. Courtesy of Jessica Hodgin,
Georgia Tech Animation Lab Water Simulation Project.
Choreographing an animation through water (swimming?) is similar to animations in thin air; except the motion should be slower and more fluid. A boat smoothly sailing over a body of water is most likely to have a smooth spline path, with no abrupt changes in motion of viewpoint. A creature (heron, or human, etc.) splashing through water is likely to have motion characterized by regular short stops, and possibly abrupt changes in motion. Swimming underwater is getting rather far from the landscape experience, and scope of this book, but can best be modeled by smooth motion coupled with appropriate cues (bubbles, splashing surface, possibly a face mask, etc.) Subdued lighting and heightened distance haze, or murkiness, can also add to an underwater feeling.
Figure 4.20 Simulated Flooding of the Williamette
River in Oregon. From the University of IOregon, Eugene, Courtesy of Maureen
Raad and David Diethelm.
Effectively modeling the motion of water requires either a very good "painterly" approach to capturing the essential visual qualities of moving water, or some computational tools that actually use physics-based simulation techniques, whether simple or extremely sophisticated, to create waves, turbulence, eddies and the other characteristics of fluid dynamics. Some modeling and rendering software has various "special effects" for water motion embedded, whcih can be used for both animation and captured still images of moving water.
Figure 4.21 "Alaska": rendering of a river scene with floating logs and water turbulence. Modeled and rendered in Animatek World Builder. Courtesy of Igor Borovikov
Figure 4.22 "Sea Gulls"; a frame of
an Animation showing breaking ocean waves, created in Animatek World Builder.
Courtesy of Igor Borovikov.
Click here for Animation of "SeaGulls".
The complex forms and patterns made by wind passing over water, which we perceive as waves, small or large, follow a basic mathematical structure: all waves can be characterized by amplitude (height) and frequency (horizontal spacing), and under physical conditions, some decay of these two over time or distance. Under normal conditions, these are fairly regular, so basic waveforms have a repeating, regularly-spaced characteristic. This regularity is ordinarily modulated by local variations and randomness, so that mathematically pure waveforms are usually not found in nature. Also, waves in fluids travel, reflect, and intersect, so that in a contained volume, there are many and complex interactions of waveforms at work.
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Figure 4.23 a A complex series of waves, with higher
and lower frquency waves superimposed, makes a realistic ocean surface. b. A
simple ripple in a flat surface.
Click here for Animation of Waves.
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Technical Note Waveforms can be smooth or jagged: sawtooth, and square-wave forms are encountered in electronics, but in nature mostly it's the smoothly curved ones we are interested in. The sine wave, which has the form y = sin x , in 2D, or z = sin (distance(x,y)) in 3D is used universally to create many different natural phenomena, and has characteristic peaks and troughs. All waveforms can be described by four quantities: frequency, amplitude,
decay rate, and phase. A simple animation of a wave can be created by setting the phase to change over time, so the wave appears to roll; the higher the phase change, the more sequential peaks and troughs will appear over time. |
In nature, water usually finds its course embedded in the terrain, from rivers and streams to the deep chasms of the Grand Canyon, with extremely gentle, often nearly horizontal, slopes. Sometimes, however, when the underlying geologic surface is hard enough, water falls over rocks, creating cascades and waterfalls. Under the influence of obstacles and gravity, water loses its placid and flat surface, and becomes undulating, ropy, streaming, and tumultuous.
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Figure 4.24 a. A waterfall in nature. b. A model of
a waterfall, using particle systems for the falling water and deflectors, reflection,
and transparency in the pool below. Modeled and rendered in 3DStudio Max.
Click here for Animation of Waterfall.
Artificial fountains are sometimes designed to look and behave just like natural waterfalls, so all of the same techniques apply. Often, however, built fountains have strongly architectural details to them, and unnatural waterforms, such as spouts and sprays, which benefit from other modeling techniques.
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Figure 4.25 Model of a fountain with water falling
from a channel in a brick wall into a basin Modeled and rendered in 3DStudio
Max. (See also the animation on Website .)
Inspired by water fountains of the landscape architect Luis Barragan. .
Click here for Animation of Fountain.
[HOW-TO: WATERFALL OR FOUNTAIN] <- Click here to see the Tutorial
Water makes sound - almost musical in some cases. Synchronizing sound to images is an art beyond the scope of this text, but there are many multimedia software systems designed for production of mixed sound and video. Adding sound to a landscape model is tricky to do in an effective way, but can often add depth and expression to models with water elements if done well. Modeling and rendering software needs to be augmented with special multimedia or video-editing software in order to be able to handle sound files, and cutting and mixing soundtracks. Creating sound is also a domain for specialized software; in most cases it's easier to capture sound with a microphone and tape recoder (or digital recorder) in the field, and use the software to manipulate and modify the sounds with digital effects as desired. Many pre-recorded sounds in digital format (.AIFF and .WAV files) are available on the Internet and on Website .
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Figure 4.26 Detail of a sound file displayed in sound-editing software.
Click here for some sounds of Water.
Water is best modeled in the landscape using some combination of color, reflectivity and transparency. Water surfaces may be flat in early morning, but are more likely rippled by wind and other actions, which can be modeled by a series of algorithmically controlled sinusoidal ripples or waves. Moving water can be animated using a combination of rippling, twisting, morphing, and other effects, especially particle systems. Particle systems are especially effective for sprays or gravity-controlled water. Digital models of water are especially enhanced by multimedia technology, adding sound to the presentation,whether still or animated.
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Campbell, Craig S. Water in Landscape Architecture. New York, NY: Van Nostrand Reinhold Co., 1978.
Halprin, Lawrence. Cities. Cambridge, MA: MIT Press, 1963.
Litton, Jr., R. Burton, and Robert Tetlow. Water and Landscape: An Aesthetic Overview of the Role of Water in the Landscape. Port Washington, NY: Water Information Center, 1974.
Figure 4.27 "Pine islands" an imaginary landscape with stone islands and dramatic pine trees. Modeled and rendered in Animatek World Builder. Courtesy of Igor Borovikov
Figure 4.28 "Ops Pool" an imaginary pool in a forest setting. Modeled and rendered in 3DStudioMax. Courtesy of Olli Pekka Saastamoinen.