With the introduction of satellites and the refinement of remote sensing technologies, these eyes-in-the-sky have played an increasingly important role in the affairs of the unsuspecting masses below.
Today, computer technology is further expanding the applications of this space-aged tool and a new frontier of practical uses for remotely sensed data is being explored.
One such effort, currently under way at Sam Houston State University, is utilizing aerial photography in ongoing efforts to monitor the earth's fragile environment.
Working under the auspices of the Texas Regional Institute for Environmental Studies, a multidisciplinary team of SHSU professors is developing new techniques for enhancing remotely sensed data in order to detect changes in the planet's ecology.
Funded by TRIES for the past two years, the remote sensing group was recently awarded a $740,000 contract by the Strategic Environmental Research and Development Program, a federal agency providing support for environmental research.
Under its agreement with SERDP, the TRIES remote sensing team will continue its theoretical research in image processing and software development. In addition, the researchers have been asked to create a software interface allowing Internet access to the image enhancing computer programs the group is developing.
Ultimately, scientists across the globe will be able to use standard Web browsing software to submit remotely sensed data for analysis, explained Patrick Van Fleet, the project director.
SERDP's interest in the project, he said, evolved from the Department of Defense's efforts to monitor environmental developments on U.S. military bases.
"The military is interested in preserving endangered species habitat," he said. "It is a lot cheaper to remotely sense a region--to snap a picture--than it is to send a group of people out to try to figure out what kind of vegetation is there, how it's being harmed, and how it's changing."
A survey crew would also have to contend with the hazards of unexploded ordinance often found on these bases, he said.
In the initial phase, the TRIES team is developing a series of image analysis routines, or modules, which mathematically enhance or manipulate remotely sensed data. The routines employ a series of statistical and/or mathematical algorithms as well as new technologies, such as wavelet analysis. Each module is designed to perform a specific task, such as defining boundaries, registering multiple images, analyzing multispectral data, or detecting and assessing change between images.
In the analysis process, a tonal value between 0 and 255 is assigned to the three colors that comprise each pixel on an image area. Pixels are the small dots--typically composed of combinations of red, green and blue--that combine to create a digital image.
Once the image is translated into a series of numbers, it can be mathematically rearranged or combined with corresponding images to produce often surprising results.
"The images are transformed into a new setting that might make those things you're looking for a little more clear," said Van Fleet.
TRIES's modules target ecological characteristics of the land sometimes undetectable in the original data. In the manipulated images, these features--river beds, treelines, soil conditions, etc.--are enhanced.
Scientists can use the enhanced data to monitor the environmental status of a region over a period of time. Through the comparison of new remotely sensed data with that of the same area collected in the past, Van Fleet said scientists can determine the extent to which the area has changed.
Once the modules are sufficiently developed, he said, the software will be installed on a powerful computer that can quickly perform the intense number-crunching calculations the program requires.
Making the modules and the computer interface accessible on the Internet, Van Fleet said, will allow users to take advantage of intense computational capabilities that may otherwise be unavailable.
In addition, he said, by centrally locating the program, users won't have to contend with installing and maintaining the software.
"The idea," Van Fleet explained, "is to try to make it automated and understandable enough that lay people can benefit from it, yet maintain an option so experts can manipulate it too."
The eight SHSU professors working on the project are statisticians: Cecil Hallum, Mark Carpenter, and Jaime Hebert; mathematicians: Harry Konen, Wasin So and Patrick Van Fleet; computer scientist Johnny Carroll; and biologist Lee Graham.
Several SHSU graduate and undergraduate students are also contributing to the project.
"These students are getting opportunities that many students never get," Van Fleet said. "They really enjoy what they are doing and I think they realize that this might put them a step up on career competition."
The Texas Regional Institute for Environmental Studies was established in 1991 as a collaborative effort between Sam Houston State and Stephen F. Austin universities. TRIES provides a mechanism for using a comprehensive, interdisciplinary approach to obtain solutions and establish policies for regional environmental issues.