|The appearance of landscapes and individual stands after harvest
operations is critical to public acceptance of timber harvest practices.
Thorough planning, detailed site-specific analysis, and careful monitoring
of harvest activities will not result in truly successful operations if
the public views the resulting landscape as an eyesore. Activities intended
to mitigate the visual impact of harvests include modifying unit boundaries
to conform to topography and other natural stand openings, prescribing
silvicultural treatments that retain higher numbers of standing trees or
groups of trees, and attempting to "hide" or "screen" harvest units from
sight. These mitigation efforts can be successful. However, foresters charged
with designing harvest unit shapes and silvicultural treatments often find
it difficult to develop visually acceptable solutions by working in the
field or with planimetric maps and aerial photographs. Visualizations depicting
the appearance of a treatment or harvest operation provide important feedback
during the design process and help to communicate management intentions
to resource specialists and public stakeholders.
Forestry professionals have used visualization techniques to address a variety of forest management problems. Prior to the advent of computerized methods, they used "artists' renditions" to communicate the effects of land management activities. Perspective sketches and scale models continue to help communicate the spatial arrangement and extent of management activities to the lay public. However, current practices in forest management involve more detailed harvest designs involving small treatment areas scattered over larger landscapes and the removal or modification of specific stand components. Alternative treatments utilize different mechanical methods, vary the spatial arrangement of treatment units, and specify different levels of modification within individual treatment units. With such treatments, the traditional "artists' rendition" cannot be made specific enough to represent the subtle differences between alternative treatments.
Computerized visualization methods range from simple diagrams to complete virtual realities. Four methods are commonly used to produce visual representations of forest operations: geometric modeling, video imaging, geometric video imaging, and image draping.
Geometric ModelingGeometric modeling methods build geometric models of individual components (ground surface, trees, other plants, and structures) and then assemble the component models to create an image of a forest stand or landscape. Scenes depicting the complete model are then rendered from a variety of viewpoints. In its simplest form, this technique can be used to generate perspective drawings showing typical GIS data coverages such as roads, streams, and polygon data overlaid onto the ground surface. More complex applications build detailed models of individual trees that include small branches and leaves for use in rendering.
Video ImagingVideo imaging uses computer programs to modify scanned full-color video or photographic images to represent changes to stand and landscape conditions. Video imaging produces television-quality (or better), full-color visual representations that depict current and future conditions. Video imaging typically requires a library of images representing different forest conditions to replace portions of an original image, however, direct manipulation of images is also possible.
Geometric Video ImagingA hybrid approach, termed geometric video imaging for this discussion, combines geometric modeling and video imaging techniques to produce very realistic images that accurately represent data describing the effects of forest management activities. Operators use geometric modeling to produce scenes that specify the location, arrangement, and scale of proposed landscape changes. Video imaging is then used to modify a digitized image to reflect these changes. The technique can be extended to use geometric modeling to determine the locations for digitized images, or icons, of single trees. Hybrid approaches result in images that accurately reflect the data describing proposed changes. However, to produce photo-like images, hybrid techniques require extensive libraries of tree and stand images that represent an appropriate range of species, tree sizes, growth forms, and landscape positions.
Image DrapingImage draping mathematically "drapes" an image over a digital terrain model and then renders the resulting scene from a variety of viewpoints. Operators usually obtain the image from a satellite scene, aerial photograph, orthophoto, or map sheet and use techniques common to video imaging to modify the original image to reflect management activities. Several GIS and image processing applications provide draping capabilities. Most include rectification procedures to properly orient and align a digital image to the ground surface. Simple applications utilize orthophoto images that have already been registered to the ground surface and corrected for elevation, or relief, displacement.
|Software package||Visualization technique||Project scale||Computer platform||Cost*||Contact information|
|Stand visualization system (SVS)||Geometric modeling||Plot||PC-DOS||Free||http://forsys.cfr.washington.edu/svs.html|
|UTOOLS and UVIEW||Geometric modeling||Stand or landscape||PC-DOS||Free||http://forsys.cfr.washington.edu/utools_uview.html|
|SmartForest||Geometric modeling||Stand or landscape||UNIX (SGI or IBM-RS6000 with OpenGL), Windows 95 (with OpenGL), Windows NT||Free||http://www.imlab.uiuc.edu/SF|
|Landscape management system (LMS)**||Geometric modeling||All scales||PC-Windows||Free||http://silvae.cfr.washington.edu/lms/lms.html|
|Adobe Photoshop||Video imaging||All scales||PC-Windows, macintosh, UNIX||$$||http://www.adobe.com/prodindex/photoshop/main.html|
|Gnu Image Manipulation Program (GIMP)||Video imaging||All scales||UNIX||Free||http://www.gimp.org|
|Paint Shop Pro||Video imaging||All scales||PC-Windows||Free, $$||http://www.jasc.com/psp.html|
|USFS, Southern Research Station visualization system||Geometric modeling||Stand or landscape||UNIX||Free||http://so4702.usfs.auburn.edu/research/prob4/standviews.html|
|VistaPro3||Geometric modeling and image draping||Landscape||PC-DOS, PC-Windows, macintosh||$$||http://www.romt.com/Products/VISTA/index.html|
|IDRISI||Image draping and perspective views||Landscape||PC-DOS, PC-Windows||$$||http://www.idrisi.clarku.edu|
|Persistence of vision raytracer (POV-Ray)****||Geometric modeling||All scales||Many platforms||Free||http://www.povray.org|
|VisualFX||Geometric modeling||Stand or landscape||PC-DOS||$$||Available from developer: John Heasley (970) 223-3149|
|CLRview||Geometric modeling||Stand or landscape||Silicon Graphics IRIX||Free||http://www.clr.utoronto.ca/CLRVIEW/cvmain.html|
|Visual Explorer||Image draping and geometric modeling||Landscape||PC-Windows||Free, $$||http://www.woolleysoft.co.uk|
|TruFlite||Image draping||Landscape||PC-Windows||Free, $$||http://www.truflite.com|
|World Construction Set||Geometric modeling||All scales||PC-Windows, Amiga, DEC ALPHA with Windows NT||$$||http://www.dimensional.com/~questar|
Questions or comments regarding this page should be directed to Robert
J. McGaughey (email)