Game Development Reference
In-Depth Information
the content for Chapter 5. Find the two RAW iles called Benchmark_heights.raw and Benchmark_255.raw and
save them to a special folder called Terrain Benchmarks. Use the terrain upload options in the Region/Estate
menu under the Terrain tab to load in Benchmark_heights.raw for the irst test, and then replace that with the
Benchmark_255.raw ile. In the upper image of Figure 5.7, you can see how Benchmark_heights.raw will step
the terrain in response to the values in the RAW image and in lower image of Figure 5.7 you can see what a
smooth steep terrain Benchmark_255.raw will produce. Try landing your avatar on various parts of these two
terrains, to see what the elevation is at various locations. This will give you a good idea of how your sim will
react to various values in a height map ield. Notice that the terrain textures in Figure 5.7 have been made in
4 simple shades, white, light gray, dark gray and black. Notice how the simulator program makes splotchy
blurs on the edges of the terrain textures where they meet on the terrain.
Let's utilize the information you have discovered from these benchmark examples of land heights and
proceed to making an accessible terrain called Wheely Island.
5.4
MAKING WHEELY ISLAND, A WHEELCHAIR-ACCESSIBLE VIRTUAL PARK
Before you start terraforming, consider this question. Virtual environments have been used extensively to
train motorized wheelchair users since the late 1990s [4], and the numbers of wheelchair-accessible nature
walks in our national parks have been increasing every year. Let's take on the dual challenge of making a
beautiful virtual landscape that is also accessible to all, designed for ease of use in movement and visibility.
In real life, you may not need a wheelchair to get around, but understanding how to build for accessibility in
a virtual space is the sign of a well-rounded virtual environment designer. For the purposes of building this
park, you are going to follow the guidelines set out by the American Trails Organization, speciically the
guidelines utilized by Malibu Parks, California (see pp. 7 and 13) [5].
In general, we want to consider the width of the boardwalks (5 meters wide is acceptable), the cross
slope (no more than 1:50), and a running slope of 1:20 for our Wheely Island visitors. The maximum run-
ning slope of 1:12 for 60 meters (200 feet) will have to be interspersed with level resting spots. Turnaround
spots will have to be provided, as well as railings to prevent a wheelchair from running off the boardwalks.
This environment should also be fun to visit, so you should consider the idea of running the boardwalk near
the water as well as making platforms overlooking some interesting features like cliffs and perhaps a sea
volcano. In this project, the initial design concept was roughed out in SketchUp, as shown in Figure 5.8.
5.4.1
r
oughing
in
The
T
errain
s
hapes
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W
heely
i
sland
u
sing
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ife
T
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Now that you can see the overall plan for this island, let's move onto making the actual terrain height map for
it. Assuming that you have downloaded the content for this chapter, open up the pre-made iles for each step
in a paint program such as Photoshop or GIMP so you can reference them as the project proceeds. Note that
the RAW ile must be opened as a 256 × 256 pixel image in RGB with 13 channels, and you should open both
the Layers menu and the Channel menu, if you are working in Photoshop, or their equivalents in your favorite
graphics program. The 13 channels are a legacy structure for terrain height maps. These were originally used
to control land properties such as parcel division, lying, and such. Now, the simulator just uses three of these
channels: the red one (channel 1) deines the height ield as 0-255 meters; the green one (channel 2) deines
the height multiply factor, allowing for the elevation value of a terrain to be raised by multiplying it with a
chosen number; and the blue one (channel 3) deines the water height in meters on the sim, which is typically
20 meters. More detailed information is found in the Second Life wiki [6]. Although there are many channels
in the ile, you will only need to concern yourself with the all-black image on the red channel. At irst, the
