SmartForest, a spatially defensible, object-oriented, visualization system
Natural systems change slowly and impacts on them become evident only with the passage of considerable time. This apparent resilience of the impacted system may mask changes that are, in fact, impossible to halt and irreversible. Implementing public policy changes to slow such change is confounded by two principal aspects of the change process: First, the initial evidence of change is small in extent and severity. It is difficult to mobilize public opinion in the face of almost insignificant impacts. Second, at later stages in the change process the absolute level of change may be significant, but the evaluator may have habituated to the changing conditions and therefore be less sensitive.
These issues can be addressed by the use of computer modeling to create reliable estimates of the changes expected to occur, and by the use of computer visualization to communicate the implications of the predicted changes.
Before and after: Visualizing the effects of forest harvest operations
SmartForest is an integrated visualization and modeling tool designed to address these combined needs. Since such techniques will eventually be employed in contentious settings it is necessary to demonstrate the validity and accuracy of the resulting imagery, as well as represent the dynamics of changing systems and the uncertainties inherent in computer modeling.
Viewing the same spatial database from different viewpoints
SmartForest visualization interface
The program has been developed to enable a variety of ways to navigate a forest setting. First, the user can manually input an x, y, z spatial location and a direction of view. This allows the user to rapidly arrive at an area of interest. Although intended as a ground-level viewer it is often useful to gain a more elevated overview of the forest, for which the user can input a height above the ground. Having reached an initial position, each of the location and height parameters can be adjusted by either further keyboard input or by dragging slide bars. For even greater sense of interaction it is also possible to move by dragging the cursor within the view while holding different mouse buttons to achieve longitudinal, rotational, and vertical movement. On the desktop IBM RS/6000 Model 41T and Silicon Graphics Indigo Elan machines it is possible to achieve movement at up to five frames per second. On machines with less graphics capability speeds are slower.To enhance interaction speed a number of compromises have been made. First, while moving the program displays a reduced number of tree locations and only as trunk height bars. On ceasing movement the remaining trees are drawn and the icons changed to a simple shaded triangle form. This image is not realistic but is useful for the majority of analyses. If required, however, it is possible to substitute textured tree symbols. This more intensive rendering can take 15-30 seconds. Another means of enhancing interaction speed is to reduce the "horizon" in the image. A less extensive landscape will draw more rapidly allowing faster interaction until a point of interest is reached at which time the horizon can be extended to give the complete landscape-scale view. Typical times for drawing a landscape view 20 x 20kms are 5-8 seconds.
At present tree color and form are preset according to the species represented in the tree list. Current development will make this function interactive, enabling target trees or groups to be selected by various parameters and given special coloration (e.g., color all hardwoods yellow).
Colored by species, top, and by diameter below
Four years of change, a schematic view; and a thematic view colored
by height
For more details a descriptive paper is available at:
SmartForest: A 3-D Interactive Forest Visualization
and Analysis System
SMARTFOREST-II: PERFORMANCE
- The forest
- Imports standard format terrain and forest data
- Supports point and click interaction with the displayed data
- Operates at full landscape scale--up to 30 X 30 km
- Allows simultaneous detailed views and overviews
- The computer
- Supports 40 million+ potential object locations
- Real-time motion (2-5fps) on a Silicon Graphics Indigo Elan
- Written in C with OpenGL graphics for portability
- Tested on Silicon Graphics and IBM RS6000 platforms
SMARTFOREST-II: THE NEED FOR INCREASED IMAGE REALISM
Realism vs. speed
To date the emphasis has been on achieving the interactivity and speed
needed to support planning activities. To achieve a tool that has uses
in the public as well as scientific arena we need to generate better looking
images from the same numeric data. Colleagues Midori Kitagawa DeLeon and
Don House at Texas A&M University created the images below from numeric
algorithms describing branching patterns etc. These types of graphics
will become available as computer speed improves.
