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Visualization
Graphics, specifically data visualizations, are usually the simplest
and most powerful means for communicating results. This important
concept has been expanded to include the use of visualizations for
representing geographical data, or geovisualizations. Geovisualizations
can differ in their complexity and quality, from photorealistic
products, to block structures with textures painted on them to simple
imagery draped over an elevation model. Most of our work at the
University of Kansas deals with photorealistic visualizations that
include lighting and atmospheric effects, detailed vegetation modeling
and complex animation ability. These realistic visualizations of
natural landscapes, often called virtual worlds or virtual environments,
provide a delivery tool for the results of environmental change
studies and management plans, especially concerning forested environments.
Geovisualizations can also be used to form hypotheses and explore
data more effectively than traditional graphic representations.
Until recently,
forest visualization efforts have focused primarily upon illustrating
static concepts or possible outcomes of management actions. Visualizations
can be enhanced by animating the static visualizations through time,
benefiting from the fact that, perceptually, human vision is "hardwired"
to detect motion. In addition to animation through time, visualizations
can also use animation to move the viewer through a three-dimensional
landscape. The combination of visualization and animation can provide
a more effective representation of data describing changing land
cover.
Software
Visualization and animation tools are still quite rudimentary in
commercially available remote sensing and GIS software packages.
By combining the functions of numerous pieces of software it is
possible to demonstrate what a single geospatial package may someday
be capable of producing. This project relied on five different types
of software: Remote Sensing image analysis, GIS, image editing,
video editing, and landscape visualization. After an exhaustive
search, 3D Nature's Visual Nature Studio (VNS) was chosen as the
most appropriate photo-realistic visualization software package
for exploring forest rendering techniques at a variety of scales.
Along with its lifelike rendering ability, VNS was selected for
a number of other specific qualities:
- Integration
with georeferenced GIS datasets
- Flexibility
of land cover type development using "ecosystems" and
"ecotypes"
- Use of raster
or vector formats to drive rendered vegetation components
- Both motion
and time-series animation ability.
Project Design
Before starting any visualization project it is important to consider
the available data, the size of the study area and the intended
use of the resulting products. For Yellowstone, the visualizations
attempted to accurately recreate the landscape and vegetation communities,
as determined from multi-spectral imagery, at scales ranging from
the entire park landscape down to individual stands of trees. The
Kansas project used a more temporally rich but spectrally poor data
set, in the form of six sets of panchromatic airphotos taken from
1941 to 2002. Due to the difference in data types, the Kansas visualizations
were constructed with the goal of capturing the process of forest
cover change within a much smaller study area by focusing more on
animation techniques than accurate tree type representations. Taken
individually, each static or animated visualization product provides
a unique method for displaying diverse aspects of forest cover change.
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