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photogrammetric plotters. In most instances, data files 
from these data capturesystems are then exported into 
a GIS for further analysis and product finishing. 
On the other hand, the environmental and resource 
management communities usually rely on multispectral 
remote sensing systems, such as Landsat and SPOT, to 
derive their data. Because of the favorable geometry 
inherent in many of these systems, adjustment to the 
GIS coordinate system has typically been accomplished 
with relatively simple polynomial warping models, 
based upon common control points, with no rigorous 
modeling of the geometry of the sensor system. Data 
from these remote sensing systems are usually 
extracted directly from the soft copy images, either by 
multispectral feature classification methods, by 
digitizing the vector outlines, or by combinations of 
both methods. The interface to the GIS is typically 
interactive on a common workstation with the image 
processing software. 
After analyzing future remote sensing processing needs 
in the USGS and other U.S. Government civil agencies 
the USGS observed that the precieved boundaries 
between mapping and environmental remote sensing 
frequently overlapped in addressing current problems. 
Some of the more advanced remote sensing systems, 
such as SPOT, can look off nadir to a significant 
degree; therefore, the effects of relief displacement on 
the plotted position of features must be considered. 
This positioning requires mathematical rigor beyond 
the ability of the simple polynomial warping model. 
The National Aerial Photography Program (NAPP) 
provides a source for relatively high-resolution 
panchromatic and color infrared images that many 
users have found to be a useful complement to 
traditional remote sensing data. The prospect of the 
ready availability of digital orthophoto quadrangles 
(DOO) derived from NAPP imagery increases the 
need to be able to exploit all of these sources 
concurrently in a common workstation environment. 
The NARSAP is designed to provide an environment 
where personnel from various civil agencies, with help 
and guidance from USGS personnel, can use these 
advanced remote sensors when addressing their 
problems. These problems may include: disaster relief 
from such phenomena as volcanic eruptions, 
earthquakes, hurricanes, and floods; as well as 
scientific experiments on earth processes, land use and 
land cover determination, geologic structure, and 
stream mixing patterns; or monitoring of stream flood 
stages, erosion, wetlands loss, potential volcanic 
activity, land cover, and dam safety. This list is 
certainly not exhaustive. 
Because virtually all of the civil agencies have ongoing 
programs that use remote sensing and GIS’s, the 
NARSAP facility needed the capability to ingest 
information from these external systems and to 
transfer information back to these same external 
systems for further analysis. In particular, adherence 
to the Spatial Data Transfer Standard (FIPS 173) 
vector and raster profiles was desired, with 
implementation as soon as the profiles are operational. 
The NARSAP workstations were to be located near 
the Advanced Cartographic System (ACS), a primary 
component of the USGS’s modernized map production 
system. Because the workstations would be required 
to exchange GIS and other data with the ACS 
workstations, there had be compatibility with that 
system. 
The NARSAP system acquisition began with the intent 
to purchase a commercial off-the-shelf (COTS) 
system, specifying the system in the broadest possible 
functional terms so that the specifications could be 
met by vendors’ standard product lines rather than 
customized products. Innovation on the part of 
respondents was welcomed. If a function required by 
the specification could be met by a product in an 
acceptable manner other than that defined by the 
specifications, the vendor was encouraged to address 
the alternative. It was preferred that the functional 
requirements be met by a truly COTS system rather 
than by special modifications to a system. 
SYSTEM REQUIREMENTS 
When the NARSAP specifications were being 
developed, three points were stressed: 
1. The system specifications would have to be 
written in the broadest possible terms so that 
they could be met by standard product lines. 
No custom development was to be involved in 
the procurement. 
2. The initial system configuration would have 
to provide basic processing capabilities for 
testing potential applications. 
3. Because it is impossible to forecast what 
new capabilities will be developed or where 
they will come from, the initial system must 
be as open as possible to future 
enhancements. 
A block diagram of a first draft is shown in figure 1. 
Its purpose was as much to help the USGS understand 
what was needed as it was to help prospective 
contractors. The final configuration was clearly left to 
the contractors to propose. 
Workstations were to have stand alone capability. 
However, a Transmission Control Protocol/Internet 
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