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SPATIAL DATA REVISION: TOWARD AN INTEGRATED SOLUTION USING NEW TECHNOLOGIES 
J. Raul Ramirez, Ph.D. 
The Ohio State University Center For Mapping, USA 
Commission IV, Working Group 4 
KEY WORDS:  Geomatics/GIS, Cartography, Revision, Model, Digital 
ABSTRACT: 
Geographic Information System (GIS) is one of the fastest growing technologies in the world. Its ability to analyze and provide answers 
to many spatial problems is impressive. Spatial data are the backbone of GIS analysis, but only current and accurate spatial data can 
provide the appropriate framework for successful use of GIS technology. Out-of-date and/or inaccurate spatial data could contaminate 
GIS results. Therefore, there is a great need for cost-efficient spatial data revision and quality control methods. 
The Center for Mapping is involved in a large spatial data conversion effort, the Generating Information from Scanning Ohio Maps 
(GISOM) project. The GISOM project is converting to computer-readable form all 793 7.5-minute quadrangle maps produced by the 
U.S. Geological Survey (USGS) covering the State of Ohio. The average age of these maps is twenty years. The Center recognizes the 
capital importance of revising these data in order to have the base needed by the State of Ohio to make full use of GIS technology. 
The Center for Mapping is developing a conceptual framework for spatial data collection (including conversion) and revision and 
investigating how to integrate local collection and revision of spatial data with modern technologies such as: mobile mapping systems, 
spatial data conflation, digital photogrammetry, digital terrain models, etc. This paper presents a summary of the conceptual framework 
of spatial data collection and revision and describes the GISOM project and the latest results of our spatial data revision research. 
  
Finally, future research directions are discussed. 
1. INTRODUCTION 
Geographic Information System (GIS) is a growing technology. 
More and more users are finding its capability to analyze and 
query geographic information of incredible help in understanding 
the environment and making better decisions. Today, the major 
limitation to the use of GIS technology is the limited availability 
of digital spatial data. As an example, in 1991, less than 5% of 
the maps of the United States of America at scale 1:24,000 (the 
primary topographic map series) had computer-compatible 
representation. 
Collection of computer-compatible spatial data in vector format 
is a costly and time-consuming process. The two major 
approaches are: (1) digital spatial data collection from the terrain 
(using remote sensing or mobile mapping systems techniques or 
a combined approach) and (2) conversion of existing maps into 
digital representations. Both approaches are operator-intensive. 
Mobile mapping systems currently offer the highest degree of 
automation and accuracy for the collection of road and railroad 
data. However, the collection of all the data included in a general 
purpose spatial database requires a lot of human intervention. 
It took almost forty years and hundreds million of dollars for the 
USGS to complete the analog coverage of the United States at 
scale 1:24,000. It can be argued that a country the size of the 
United States is impossible to remap (in digital form) in entirety 
because of cost and time constraints. The most cost-efficient 
solution to generate the digital spatial data needed by GIS in a 
country the size of the United States is, perhaps, a combination 
of remapping selected areas, conversion of existing analog maps, 
and revision of digital spatial data. This paper introduces the 
677 
topic of spatial data collection and revision, describes briefly the 
map conversion effort at the Center for Mapping, describes the 
status of our research in this area, and finally, discusses future 
research directions. 
2. SPATIAL DATA REVISION 
Spatial data revision is defined by Ramirez (1996) as correcting, 
updating, and improving the content of existing data to obtain a 
current representation of the terrain, in agreement with a 
predefined purpose. The revision effort at the Center for 
Mapping is directed toward the DLG-3 files generated by the 
GISOM project. 
Conventionally, spatial data revision requires the use of current 
aerial photographs and manual identification and compiling of all 
the changes on the terrain. With the increasing use of 
computer-based methods, partial revisions are possible today. 
There is not a universally accepted spatial data revision method. 
In general, spatial data revision is agency dependent. For the 
purpose of providing an example of revision, a brief description 
of the USGS’s method follows. In agreement with Thompson 
(1987) and others, map revision is divided into four major tasks: 
total revision, partial revision, photorevision, and photo- 
inspection. Total revision is the “correction of all deficiencies in 
planimetry and relief features” and it is the only type of revision 
that keeps a consistent terrain representation. Photo-inspection is 
the process of “comparing the latest published map to recent 
aerial photographs to determine both the need for revision and 
the extent of the changes.” 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B4. Vienna 1996