Geographic Information Systems:
Standards and Guidelines
in the State of Georgia
Compiled by the
Base-Map Technical Working Group for the
GIS Advisory Committee of the
State of Georgia Information Technology Policy Council
[This document was originally created in 1998-1999 by the GISAC– Converted to PDF in 2012 as an archived reference document by
GISCC Website Subcommittee]
Table of Contents
1.0 Introduction
1.1 Base-Map Technical Working Group (BMTWG)
1.2 Update Process
1.3 Applicability
2.0 Data Layer Classification
2.1 Hierarchical Scheme
2.2 Naming Conventions
3.0 Cartography
3.1 Datums / Hydrographic Standards
3.1.1 Horizontal Datums
3.1.2 Vertical Datums
3.1.3 Hydrographic Standards
3.2 Projections and Coordinate Systems
3.2.1 Latitude - Longitude (Geographic Coordinates)
3.2.2 State Plane Coordinate Systems (1927 and 1983 datums)
3.2.3 Universal Transverse Mercator (UTM)
3.2.4 Georgia Statewide Lambert Conformal Conic
3.2.4.1 Map Projection
3.2.4.2 Ellipsoid
3.2.4.3 Datum
3.2.4.4 Longitude of Origin
3.2.4.5 Latitude of Origin
3.2.4.6 Standard Parallel 1
3.2.4.7 Standard Parallel 2
3.2.4.8 False Easting
3.2.4.9 False Northing
3.2.4.10 Unit of Measurement
3.2.5 Georgia Statewide Albers
3.2.5.1 Map Projection
3.2.5.2 Ellipsoid
3.2.5.3 Datum
3.2.5.4 Longitude of Origin
3.2.5.5 Latitude of Origin
3.2.5.6 Standard Parallel 1
3.2.5.7 Standard Parallel 2
3.2.5.8 False Easting
3.2.5.9 False Northing
3.2.5.10 Unit of Measurement
3.3 Map Transformations
3.4 Map Legend and Supplemental Information
3.4.1 Map Title
3.4.2 Scale Representation
3.4.3 Map Dates
3.4.4 Author
3.4.5 Disclaimer
3.4.6 Source(s)
3.4.7 North Arrow
3.4.8 Symbology Key
3.4.9 Projection/Ellipsoid/Datum
3.4.10 Grid Lines or Intersection Ticks
3.5 Standard Hardcopy Output Scales
3.5.1 Site Specific Scales
3.5.2 Map Scale 12,000
3.5.3 Map Scale 1:24,000
3.5.4 Map Scale 1:25,000
3.5.5 Map Scales 1:15,840, 1:31,680, and 1:63,360
3.5.6 Map Scales 1:63,360, 1:126,720, and 1:253,440
3.5.7 Map Scale 1:62,500
3.5.8 Map Scale 1:100,000
3.5.9 Map Scale 1:250,000
3.5.10 Map Scale 1:500,000
3.5.11 Map Scales 1:1,000,000, 1:1,250,000, 1:1,500,000, and
1:2,000,000
4.0 Data Capture
4.1 Map Precision
4.1.1 Latitude and Longitude Values
4.1.2 X,Y or X,Y,Z Coordinate Values
4.2 Map Accuracy
4.2.1 Horizontal Accuracy
4.2.2 Vertical Accuracy
4.3 Scale Abuse
4.3.1 Scale Mixing
4.3.2 Scale Misrepresentation
4.4 Sources for Map Compilation
4.4.1 Existing Digital Maps
4.4.2 Original Digitizing
4.4.2.1 Digitizing From Other Than Hardcopy Maps
4.4.2.2 Digitizing From Hardcopy Maps (7.5' USGS Quads)
4.4.2.2.1 Generational Slippage
4.4.2.2.2 Manuscript Media
4.4.2.2.3 Registration Ticks
4.4.2.2.4 Edge matching
5.0 Data Interchange Standards
5.1 Files Transferred
5.2 Native and Direct Data Interchange Formats
5.3 Neutral Data Interchange Formats
5.4 Data Interchange
6.0 Metadata
6.1 Federal Geographic Data Committee (FGDC) Compliance
7.0 Implementation Procedures
7.1 Information Resources Manager's Certification
Appendix A. Standards for 1:24,000-Scale Digital Line Graphs and Quadrangle Maps:
Digital Line Graph - Enhanced
by the U.S. Department of the Interior, U.S. Geological Survey, National
Mapping Division
Appendix B. Content Standards for Digital Geospatial Metadata
by the Federal Geographic Data Committee
Appendix C. Georgia Base-Map Technical Working Group Membership
Appendix D. United States National Map Accuracy Standards
Appendix E. Supplement to Section 3.2.2, 'State Plane Coordinate Systems (1927 and 1983
datums)'
SECTION 1
1.0 Introduction
This manual contains standards and guidelines for implementing and maintaining Geographic
Information Systems (GIS) for Georgia state agencies and universities. The purposes of these
standards are:
• - to facilitate development of efficient and cost-effective GIS in state agencies
• - to promote an integration of information among state agencies
• - to maximize the availability and use of data, and
• - to minimize the effort required to incorporate data from one agency into
another.
These standards and guidelines apply to digital geographic data in both raster and vector formats.
It is intended ONLY for map scales of 1:12,000 and smaller (e.g., 1:24,000; 1:100,000;
1:250,000). It is NOT intended for large-scale maps (larger than 1:12,000). It establishes
standards and guidelines for data layer classification, cartographic data including data output,
data capture and locational accuracy, data interchange formats and data documentation formats.
By conforming to these standards, state and other governmental agencies can exchange digital
spatial data more easily and readily. Thus, state agencies will no longer be developing GIS in
isolation but in a standardized fashion in which all agencies can benefit from the efforts of each
agency.
Throughout this standards and guidelines document, the terms "must", "shall", and "will",
identify a standard. Permissive wording such as "can", "may", and "should", identify a guideline.
Recognizing the need to promote both the cost-effective and useful retrieval and exchange of
information resources in state government, the Information Technology Policy Council (ITPC)
was established to provide leadership and coordination of information resources management
within Georgia state government. This Council requires the GIS Advisory Committee (GISAC)
to develop and publish standards relating to geographic information resources management. To
fulfill this mandate, the GIS Advisory Committee chartered the Base-Map Technical Working
Group in March 1996.
1.1 Base-Map Technical Working Group (BMTWG)
The BMTWG was formed in March 1996, to develop standards for facilitating information
exchange. The committee is composed of 12 members drawn from state agencies, local
governments, the academic and vendor community. This committee's role is to develop and/or
recommend GIS technical standards to the GISAC and to provide support to agencies in
interpreting standards and implementing GIS technology.
These standards are not intended, in any way, to curtail the voluntary initiatives of state agencies,
but rather to encourage agencies to maintain, expand, and continue to develop geographic
information systems with a high level of technical expertise and professionalism. The overall
objective of the BMTWG is to develop standards and procedures which will help GIS users avoid
fragmentation in data and to promote higher levels of compatibility so that GIS data and
applications can be more easily shared. Adoption of these standards will insure greater data
compatibility, reduce redundant data development efforts, and promote cooperation and
coordination among different state and local agencies. Whenever possible, federal standards will
be supported. Georgia GIS standards will not dictate the GIS software and/or hardware that a
state agency use but rather provide standardized procedures by which digital spatial data is
gathered, documented and exchanged between state agencies regardless of the developmental
software and/or hardware platform.
The BMTWG acknowledges the GIS standards from the states of Texas, Florida, Kansas,
Minnesota, New Mexico, Oregon, Montana and Vermont, as the material presented in their
standards documents was of considerable benefit to us as we prepared this document.
1.2 Update Process
The GIS environment is rapidly and continuously changing. Standards must evolve accordingly
or they may become out-of-date and/or too restrictive. For example, the Federal Geographic Data
Committee (FGDC) is developing a Spatial Data Transfer Standard (SDTS) which will become a
Federal Information Processing Standards (FIPS) when adopted by the National Institute for
Standards and Technology. The SDTS will be a uniform transfer format which Federal agencies
will be required to use in the import and export of digital spatial data. With such changes in GIS
technology, the committee will review the State's standards on a semi-annual basis or more
often, if needed, and modify them as necessary to insure that they remain useful and current.
1.3 Applicability
These standards and guidelines apply to all digital spatial data users and developers, and to all
new Geographical Information Systems being developed in Georgia state agencies and
universities. State agency means department, commission, board, office, council, or other agency
in the executive or judicial branch of government that is created by the constitution or a statute
of this state, including a university system or institution of higher education. An institution of
higher education will be exempted from these standards when Geographic Information Systems
are acquired solely for instructional purposes. Currently operating systems which are
structurally unable to comply are not required to retrofit to these standards, but agencies are
encouraged to implement as many of the standards as possible, as soon as feasible.
SECTION 2
2.0 Data Layer Classification
A data layer classification scheme organizes data in a uniform manner to facilitate database
exchange among state and local governmental agencies. The classification will be used to
arrange the agency's custodial metadata or documentation about thematic layers so those seeking
GIS databases will be able to conveniently search for and locate the appropriate type of
information. This classification scheme does not dictate the organization of the database internal
to the GIS software.
The BMTWG acknowledged the need for a standard spatial data layer classification in Georgia,
also considering the requirement to meet broader federal standards and guidelines with regard to
the USGS National Mapping Division and the FGDC’ s NSDI initiatives. It was decided that the
Standards for 1:24,000-Scale Digital Line Graphs and Quadrangles; Digital Line Graph Enhanced, revised April 1996, provided a data layer classification and attribute coding scheme
which can be successfully utilized by the State of Georgia. The Standards for 1:24,000-Scale
Digital Line Graphs and Quadrangles; Digital Line Graph - Enhanced is summarized in section
2.1 and fully incorporated into the Geographic Information Systems Standards and Guidelines
for the State of Georgia as Appendix A.
2.1 Hierarchical Scheme
An open-ended, hierarchical scheme provides the organizational structure. At the highest level,
broad data types or categories are specified ( i.e., Transportation, hydrography ). These, in turn,
are subdivided into thematic layers included in the major data category ( i.e., roads, lakes ). Each
thematic layer of data will be composed of entity (feature) types ( i.e. point, line, polygon, route,
region ) and their associated attributes.
This hierarchy can be summarized as:
A. Category ( example: transportation )
1. Thematic Layer ( example: road )
a. Entity Type ( example: linear )
I. Associated Attribute ( example: road class )
The following data classification scheme provides the open-ended framework necessary for
organizations to provide data consistent with the mission of the original collector, referencing the
entities used in its collection. Expansion of the categories and thematic layers to ensure that the
structure provides inclusive data storage for data utilized by all participating governmental
agencies.
Category
Section
Thematic Layer
2
Anchorage, Area of Complex Channels, Area to be Submerged,
Bay/Inlet, Bridge, Canal/Ditch, Connector, Crevasse Field,
Dam/Weir, Estuary, Fish Ladder, Flume, Foreshore, Fumarole,
Gaging Station, Gate, Geyser, Hazard Zone, Ice Mass, Inundation
Area, Junction, Lake/Pond, Lock Chamber, Mile Marker, Mud Pot,
Nonearthen Shore, Pipeline, Playa, Post, Rapids, Reef, Reservoir,
Rock, Sea/Ocean, Shoreline, Sink, Rise, Snag/Stump, Sounding
Datum Line, Special Use Zone, Special Use Zone Limit, Spillway,
Spring/Seep, Stream/River, Submerged Stream, Swamp/Marsh,
Tunnel, Underpass, Wall, Wash, Water Intake/Outflow, Watercourse,
Waterfall, Well, Wreck
Transportation
3
Aircraft Facility, Bridge, Cul-de-sac, Draw Span, Ford, Gate,
Helipad, Interchange, Junction, Lane, Monorail, Railway, Railway
Yard, Rest Site, Road, Route, Runway/Apron/Taxiway, Traffic
Inspection Facility, Trail, Tunnel, Tunnel Entrance, Turntable,
Underpass
Boundaries
4
Boundary Line, Boundary Point, City, County, Minor Civil Division,
Nation, Point Monument, Reservation, State/Territory
Public Land
Survey
System
5
Land Grant, Point Monument, Principal Meridian, Public Land
Survey System Area, Special Survey Area, Survey Corner, Survey
Line.
6
Aquaculture Site, Archeological Site/Ruin, Athletic Field,
Boardwalk, Building, Built-Up Area, Cable/Pipeline Site, Cableway,
Campground, Cemetery, Chimney, Conveyor, Dish, Disposal Site,
Disturbed Surface, Drive-In Theater Screen, Drydock, Embankment,
Exhibition Ground, Fence Line, Filtration Plant, Historical
Monument, Holding Pen, Institutional Site, Kiln, Launch Facility,
Launch Pad, Launching Ramp, Locale, Marina, Mine, Mine Entrance,
Mobile Home Park, Offshore Platform, Outdoor Theater, Park,
Pier/Breakwater/ Jetty, Pipeline, Pipeline Regulation Station,
Populated Place, Power Site, Prospect, Proving Ground, Racetrack,
Recreational Slide, Reservoir, Sewage Disposal Plant, Shopping
Center, Ski Jump, Sports Site, Substation, Tank, Tower, Transmission
Line, Underpass, Wall, Well, Well Field, Wharf, Windmill
Hydrography
Built-up
Hypsography
7
Contour (land), Depth Curve, Sounding, Spot Elevation
Nonvegetative
Surface Cover
8
Barren Land, Beach, Dunes, Moraine
Vegetative
Surface Cover
9
Cultivated Cropland, Shrubland, Tree, Trees
Named
Landforms
10
Arch, Bar, Basin, Bend, Cape, Cave Entrance, Cliff, Desert, Divide,
Fracture, Gap, Iceberg, Iceberg Tongue, Incline/Flow, Island,
Isthmus, Mount, Pinnacle, Plateau, Range, Ridge, Sastrugi, Terrace,
Valley
2.2 Naming Conventions
The standard naming conventions for, Categories, and Thematic Layers, as defined in the Section
2.1 Hierarchical Scheme, should be utilized throughout the GIS data structure developed by the
Clearinghouse for data exchange. The utilization of these uniform naming conventions for
thematic data layers will provide GIS data consistency when data is shared between agencies.
SECTION 3
3.0 Cartography
3.1 Datums / Hydrographic Standards
3.1.1 Horizontal Datums
While most existing maps are based on the old Clarke 1866 ellipsoid and its associated North
American Datum of 1927 (NAD 27), it is strongly recommended that new digital mapping be
built upon, when structurally possible, the more accurate Geodetic Reference System of 1980
(GRS 80) ellipsoid and its associated North American Datum of 1983 (NAD 83). Please see
sections 3.3 and 4.4.2.2.3 for additional information on this topic.
3.1.2 Vertical Datums
When vertical data is used, the North American Vertical Datum of 1988 (NAVD 88) should,
when structurally possible, be utilized rather than the old National Geodetic Vertical Datum of
1929 (NGVD 29).
3.1.3 Hydrographic Standards
Bathymetry (underwater contours) should comply with the accuracy standards set forth in the
International Hydrographic Organization's (IHO) Special Publication 44.
3.2 Projections and Coordinate Systems
The following projections and coordinate systems are recommended for the input, storage, and in
particular, the exchange of digital map data. Other projections and coordinate systems may be
used, however, to satisfy special requirements.
3.2.1 Latitude - Longitude (Geographic Coordinates)
Latitude - Longitude is a projectionless coordinate system that may be used for the input,
storage, and exchange of digital map data. Although it may also be used for the output of
hardcopy maps, it is not, however, structurally suited for that purpose.
3.2.2 State Plane Coordinate Systems (1927 and 1983 datums)
The Georgia State Plane Coordinate Systems in which map distortion has been minimized by
dividing the state into two vertical zones, must, by state law, be used for surveying and the
compilation of engineering maps. These systems may also be used for the compilation of
regional maps, but since they do not provide uninterrupted coverage of the entire state, such
mapping should not extend beyond the limits of any given zone. These systems may be used for
the input, storage, and exchange of digital map data, as well as for the output of hardcopy maps.
The Georgia State Plane Coordinate System is officially named the "Georgia Coordinate
System" or the "Georgia Coordinate System of 1985" and its legal description along with
guidelines for its use are provided in the Official Code of Georgia. The relevant sections are
provided as a supplement to this document in Appendix E.
3.2.3 Universal Transverse Mercator (UTM)
The Universal Transverse Mercator map projection system, in which the state has been divided
into two vertical zones, may be used for regional mapping, but like the State Plane Coordinate
Systems, such mapping should not extend beyond the limits of any given zone. This system may
be used for the input, storage, and exchange of digital map data, as well as for the output of
hardcopy maps.
3.2.4 Georgia Statewide Lambert Conformal Conic
The Georgia Statewide Lambert Conformal Conic may be used for the compilation of those wide
area maps (statewide and regional) whose mapping area extends beyond the limits of State Plane
and UTM zones. It is not to be used for either surveying or engineering applications. This system
may be used for the input, storage, and exchange of digital map data, as well as for the output of
hardcopy maps. Its parameters are:
3.2.4.1 Map Projection: Lambert Conformal Conic
3.2.4.2 Ellipsoid: Geodetic Reference System of 1980 (GRS 80)
3.2.4.3 Datum: North American Datum of 1983 (NAD 83)
3.2.4.4 Longitude of Origin: Central Meridian
3.2.4.5 Latitude of Origin: 0 Degrees
3.2.4.6 Standard Parallel 1: 31 Degrees, 25 Minutes North
3.2.4.7 Standard Parallel 2: 34 Degrees, 17 Minutes North
3.2.4.8 Central Meridian: 83 Degrees, 30 Minutes West
3.2.4.9 False Easting: None
3.2.4.10 False Northing: None
3.2.4.11 Unit of Measurement: Feet
3.2.5 Georgia Statewide Albers Projection
The Georgia Statewide Albers Projection may be used for the compilation of those wide area
maps (statewide and regional) whose mapping area extends beyond the limits of State Plane and
UTM zones. It is not to be used for either surveying or engineering applications. This system
may be used for the input, storage, and exchange of digital map data, as well as for the output of
hardcopy maps. Its parameters are:
3.2.5.1 Map Projection: Albers Conformal Conic
3.2.5.2 Ellipsoid: Clarke 1866
3.2.5.3 Datum: North American Datum of 1927 (NAD 27)
3.2.5.4 Longitude of Origin: Central Meridian
3.2.5.5 Latitude of Origin: 23 Degrees North
3.2.5.6 Standard Parallel 1: 29 Degrees, 30 Minutes North
3.2.5.7 Standard Parallel 2: 45 Degrees, 30 Minutes North
3.2.5.8 Central Meridian: 83 Degrees, 30 Minutes West
3.2.5.9 False Easting: None
3.2.5.10 False Northing: None
3.2.5.11 Unit of Measurement: Feet
3.3 Map Transformations
All coordinate transformations, projection changes, ellipsoid datum transformations, or any
combination thereof, must be accomplished through software (in-house or vendor-supplied)
which has been designed specifically for that purpose. All NAD27/NAD 83 conversions must
utilize algorithms or software developed by the National Geodetic Survey. Any attempt to move,
scale, and/or rotate a file graphically from one coordinate system, projection, or ellipsoid/datum
to another will compromise the integrity of the resulting file.
3.4 Map Legend and Supplemental Information
Hardcopy maps, particularly those that are intended for distribution outside an agency, should
include only the ancillary information (map title, scale indicator, etc.) necessary to make the
maps meaningful and useful for their intended users. Informational content will therefore vary
from map to map with reference maps generally needing more explanation than thematic maps.
When appropriate, the following informational elements should be used, and if used, may be
placed in either a legend or elsewhere on the map sheet.
3.4.1 Map Title
A map title briefly describes the nature of a map, for example:
General Highway Map: Early County, Georgia (Georgia Department of
Transportation) or
Landcover of Georgia: 1988-1990 (Georgia Department of Natural Resources).
3.4.2 Scale Representation
Output scales are often presented in one or more of the following formats: fractional scale (e.g.
1:24,000), scale bar, or scale in English and/or metric units. Scale bars are useful if photoduplicated enlargements or reductions are made from the original published map.
3.4.3 Map Dates
Three dates are important: 1) Compilation Date: the year or month/year of initial map
compilation; 2) Revision Date: the date of the map's last revision; and 3) Plot Date: the actual
date the map was plotted.
3.4.4 Author
The map author is the name of the agency or entity responsible for the compilation of the map.
3.4.5 Disclaimer
Disclaimers are used to limit and define the map author's responsibility for the content, accuracy,
and currency of a map. Although some maps may require specialized disclaimers, the following
is suggested:
"This map is the product of Agency, Division and was printed on Date. This map
was produced with the intent that it be used for Purpose at the scale of X. There
are no warranties made as to the fitness of this map for any unlisted purpose or
reproduction at any other than the original scale."
The agency can complete the italicized sections with appropriate information relating to the
agency and the purpose of the map. Listed below are some suggested applications or purposes of
map productions:
a. Information Management/dissemination (e.g., public inquiry)
b. Regulatory program management/operation
c. State and regional planning
d. Spatial analysis and modeling
e. Facilities management and maintenance
f. Administrative/Financial Assessment/planning (e.g., redistricting)
g. Geographic information collection (e.g., field collection, geologic inventories,
etc.)
3.4.6 Source(s)
Identification of the primary and significant secondary map sources is often useful for map users.
3.4.7 North Arrow
The geographic north arrow is used to show map orientation, but it should be noted that on the
Lambert Conformal Conic or Albers projections, the true direction of north will vary from one
side of the map to the other. This is because the lines of longitude converge as they move toward
the poles, thus making it impossible to portray anything more than the general direction of north.
Caution, and perhaps a note of explanation, should therefore be used when placing the north
arrow.
3.4.8 Symbology Key
The symbology key is a graphic and/or narrative description of the symbology depicted on the
map, and it can be included either on the map itself or in agency in-house documentation.
3.4.9 Projection/Ellipsoid/Datum
A notation identifying the projection/ellipsoid/datum upon which the map is based should be
included, particularly if a grid system is printed on the map. Standard parallels should also be
identified, although if the map is based on an established coordinate system, such as the State
Plane Coordinate System, notation of that system will suffice.
3.4.10 Grid Lines or Intersection Ticks
Grid lines or ticks should be included when the ability to plot locations is needed.
3.5 Standard Hardcopy Output Scales
Output scale is the map scale at which a map is printed, which may or may not correspond to the
scale at which the map was compiled. While hardcopy maps may be printed at any scale, the
following commonly used output scales are offered as suggestions. Refer to section 4.3 for
precautions on scale abuse.
3.5.1 Site Specific Scales
These scales vary according to the purpose for which the map is being printed, for example, the
Georgia Department of Natural Resources map entitled Landcover of Georgia: 1988-1990 that
was published at a map scale of 1:633,600.
3.5.2 Map Scale 1:12,000
This is the nominal scale of the USGS Digital Orthophoto Quadrangle (DOQ) images. In
November 1996 the Georgia BMTWG and GISAC specified the 1:12,000 scale DOQs as a
primary aerial photographic imagery source for compilation of statewide base maps.
3.5.3 Map Scale 1:24,000
The USGS Primary Map Series 1:24,000 Scale covers Georgia on 1016 of these 7.5' quadrangle
map sheets. These maps are packaged with the 1:250,000 scale maps for Georgia in the USGS
Digital Raster Graphic Map Series. The 1:24,000 map scale is also the basis for other important
federal mapping programs including:



Flood Insurance Rate Maps-Digital Line Graph (FIRM-DLG) (Federal Emergency
Management Agency)
National Wetlands Inventory (Fish and Wildlife Service)
Reach File Version 3.0 (RF3) (Environmental Protection Agency)
In November 1996 the Georgia BMTWG and GISAC specified 1:24,000 as the primary map scale
for compilation of statewide base maps. Please refer to the Georgia: Index to Topographic and
Other Map Coverage published and distributed by the USGS National Mapping Program for a
complete listing of map names.
3.5.4 Map Scale 1:25,000
This is the scale at which USGS 7.5' x 15' metric quadrangles are printed.
3.5.5 Map Scales 1:15,840, 1:31,680, and 1:63,360
The Georgia Department of Transportation county maps are published at these scales.
3.5.6 Map Scales 1:63,360, 1:126,720, and 1:253,440
3.5.7 Map Scale 1:62,500
This is the scale at which USGS 15' quadrangles are printed.
3.5.8 Map Scale 1:100,000
The USGS 30' x 60' Minute Map Series 1:100,000 maps Georgia onto 45 map sheets, e.g., the
Greater Atlanta Region (Reference Code 33083-D7-RT-100). Please refer to the Georgia: Index
to Topographic and Other Map Coverage published and distributed by the USGS National
Mapping Program for a complete listing of map names.
3.5.9 Map Scale 1:250,000
The USGS 1 x 2 Degree Map Series 1:250,000 Scale covers Georgia on 14 map sheets, e.g.,
Atlanta (Reference Code 33082-A1). These maps are packaged with the 1:24,000 scale maps for
Georgia in the USGS Digital Raster Graphic Map Series. Please refer to the Georgia: Index to
Topographic and Other Map Coverage published and distributed by the USGS National
Mapping Program for a complete listing.
3.5.10 Map Scale 1:500,000
The USGS State Map Series 1:500,000 Scale includes three small-scale Georgia maps:



State of Georgia: Base (Reference Code 33084-F4 SP-500)
State of Georgia: Topographic (Reference Code 33084-F4 ST-500)
State of Georgia: Shaded Relief (Reference Code 33084-F4 SR-500)
3.5.11 Map Scales 1:1,000,000, 1:1,250,000, 1:1,500,000, and 1:2,000,000
These are the small scales used by the USGS to print some state and regional maps. The State
Map Series at 1:1,000,000-scale includes the State of Georgia: Base (Reference Code 33084-F4
SP-01M). The National Atlas Sectional Map Series includes Georgia at a scale of 1:2,000,000
(National Atlas Sheet 10-11: Southeastern States). Please refer to the Georgia: Index to
Topographic and Other Map Coverage published and distributed by the USGS National
Mapping Program for a complete listing.
SECTION 4
4.0 Data Capture
Since the USGS 7.5 minute quadrangle is one of the paper-based maps often used for data
capture, the following standards and guidelines have been designed specifically for it, although
they may apply to other map sources as well.
4.1 Map Precision
Mapping precision is the degree of refinement (often represented in decimal places) with which a
measurement is taken and/or expressed, and it is generally determined by the map compilation
scale. For example, a precision of one foot or one meter is more than adequate for small-scale
maps (1:250,000; 1:1,000,000, etc.), whereas sub-foot or sub-meter precision is often required
for large-scale mapping.
The following engineering level precisions are suggested, although it is realized that such
precision will not always be necessary, or even obtainable (particularly without the use of
surveying and GPS).
4.1.1 Latitude and Longitude Values
Latitude and longitude values should be given to at least 0.00001 seconds.
4.1.2 X,Y or X,Y,Z Coordinate Values
X, Y, and X,Y,Z coordinate values should be given to at least 0.01 feet or 0.001 meters.
4.2 Map Accuracy
Map accuracy is the degree toward which any given feature(s) on a map conforms to its true
position on the ground.
4.2.1 Horizontal Accuracy
Horizontal accuracy should conform as closely as possible to the U.S. National Map Accuracy
Standards (NMAS). Note, however, that adherence to NMAS can usually be achieved only when
maps are compiled directly by survey, GPS, and/or photogrammetric methods, as are most
published USGS maps. While digital maps compiled from surveying and photogrammetry can
meet NMAS too, most digital maps (including USGS DLG files and U.S. Census TIGER files)
are compiled from pre-existing maps, and thus fall short of NMAS. These digital maps are
nevertheless very useful to state agencies as they may constitute the only or the best data
available.
With the above qualifications in mind, the U.S. National Map Accuracy Standards require that at
scales of 1:24,000 and smaller (for example, 1:100,000, 1:500,000) that 90% of a randomly
chosen sample of well-defined map features will be on the map within 1/50 or 0.02 inches (at
scale) of their true location on the ground. The table below illustrates the positional accuracy of
several relevant scales.
Scale Horizontal Accuracy
1:12,000 + or - 33.3 feet
1:24,000 + or - 40 feet or 12.2 meters
1:63,360 + or - 105.6 feet or 32.2 meters
1:100,000 + or - 166.7 feet or 50.8 meters
1:250,000 + or - 416.7 feet or 127 meters
1:500,000 + or - 833.3 feet or 254 meters
1:1,000,000 + or - 1666.7 feet or 508 meters
1:2,000,000 + or - 3333.3 feet or 1016 meters
4.2.2 Vertical Accuracy
Vertical accuracy should conform to the U.S. National Map Accuracy Standards, which require
that not more than 10% of the elevations tested shall be in error by more than ½ of the
contour interval.
4.3 Scale Abuse
4.3.1 Scale Mixing
The mixing of digital map data of widely divergent scales into a common database should be
avoided, as the positional accuracy of the aggregate database would be considered to be no better
than that of the smallest scale. If such mixing should be necessary, however, documentation to
that effect should be included in the Quality and Accuracy Report.
4.3.2 Scale Misrepresentation
The almost infinite zoom capability of computer graphics should not be used to produce
hardcopy maps at scales inconsistent with those of the original sources (e.g., printing a map that
was compiled from a 1:250,000 source map at a scale of 1:24,000, the scale of a USGS 7.5'
quadrangle).
4.4 Sources for Map Compilation
4.4.1 Existing Digital Maps
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Information on digital spatial data files can be accessed through the Georgia GIS Data
Clearinghouse which can provide:
Summary of the file contents,
Size and age of the file,
Available file formats,
Geographic area covered by the file,
Map scale/features (linear, point, polygon), and
The organization that owns/maintains the file and the person to contact for additional
information.
4.4.2 Original Digitizing
4.4.2.1 Digitizing From Other Than Hardcopy Maps
Primary Data Sources: global positioning systems (GPS), surveying, Digital Orthophoto
Quadrangles (DOQs) and hardcopy photogrammetric products, satellite imagery, and scanned
hardcopy maps. It is highly recommended that a Primary Data Source be utilized for new digital
data collection if possible.
4.4.2.2 Digitizing From Hardcopy Maps (7.5' USGS Quads)
4.4.2.2.1 Generational Slippage
Only first generation maps (those maps compiled directly from photogrammetry, GPS, etc.)
should be used as source maps for digitizing, as each successive generation away from the
original will result in less precision.
4.4.2.2.2 Manuscript Media
Quads should be reproduced on a stable base, such as mylar, to minimize the effects of humidity.
If this is not possible, paper maps should be detached from the table, retaped, and reregistered
frequently particularly if the manuscript would otherwise remain taped overnight or over other
long intervals. Photocopies of source maps are not suitable manuscripts for use in digitizing.
4.4.2.2.3 Registration Ticks
All 16 of the grid ticks contained on 7.5' quads (they are represented in latitude/longitude) should
be used in registering a quad to a projection/coordinate system. A minimum of 4 grid ticks must
be used for this purpose.
As noted in section 3.1.1, all new digital mapping should use the GRS 80/NAD 83. However, no
source map based on Clarke 1866/NAD 27 may be digitized directly into GRS 80/NAD 83
unless the source map also contains NAD 83 grid ticks. Otherwise, digitized data will be
displaced by as much as 36 meters (118 feet) to the west, and by as much as 3 meters (9.8 feet)
to the north.
If a 7.5' quadrangle for Georgia does not contain NAD 83 grid ticks, they must be digitized first
into Clarke 1866 NAD 27 and then converted (see Section 3.3) to GRS 80/NAD 83. However, if
mapping software contains a secondary projection (which has been defined in NAD 27), the
control points can be entered into that format, after which the digitizer setup and digitizing can
be accomplished in the primary projection (NAD 83).
4.4.2.2.4 Edge matching
Features on USGS quads (rivers, roads, transmission lines, etc.) that continue across the
boundary of one quad into another, must be edge matched so as to eliminate misalignments. It is
suggested that if the misalignment is no greater than the 40 foot horizontal accuracy of a 7.5'
quad, either feature may be edge matched to the other. If the misalignment is greater than 40 feet,
however, it is suggested that both features be matched at the point midway between their
respective positions on the quad boundaries.
SECTION 5
5.0 Data Interchange Standards
Various methods of data interchange used by state, regional, local governments and private
sector organizations depend on the complex matrix of hardware and software systems in place at
both the source and target organizations. In determining the most desirable interchange format,
considerations must be made for the preservation of accuracy and completeness, transfer
efficiency, the data type (vector or raster) and the intended use of the data.
5.1 Files Transferred
Agencies contributing digital spatial data to the Clearinghouse must complete a Preliminary
Metadata Report for all thematic layers. This report documents the nature and characteristics of
input source materials for each thematic layer in a data set. The report identifies an agency
contact person to work conjunction with the Clearinghouse to facilitate the creation of full FGDC
compliant metadata. Once FGDC compliant metadata has been completed for a given data set,
the metadata documents should always be transferred with the data set.
5.2 Native and Direct Data Interchange Formats
Native data interchange formats for vector and raster data should be used for transfers between
like software systems. If a direct interchange format exists between two dissimilar GIS software
systems, it should be used only after a detailed investigation based on the considerations stated
above in section 5.0.
5.3 Neutral Data Interchange Formats
Neutral exchange formats listed below should be used when vector data interchange in native
and direct interchange formats are not available. It is recommended that the data interchange file
generated in the formats listed below be in non-compressed ASCII format. However, if
compression of data is used to reduce file size be certain that the receiving agency has the
appropriate software to read the data. Since the Spatial Data Transfer Standard (SDTS) is
adopted as a Federal Information Processing Standard (FIPS), agencies will be required to use
GIS software which provides SDTS conversion functionality.
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ESRI Export Format (.e00)
ESRI Shape File (.shp)
Spatial Data Transfer Standard (SDTS)
Drawing Exchange Format (DXF)
Digital Line Graphs (DLG-3) standard or optional format
Initial Graphics Exchange Standard (IGES) Version 3
Standard Interchange Format (SIF)
5.4 Data Interchange
Various data interchange media are dependent on the hardware systems installed at the source
and target organizations. The users exchanging data will determine the best media based on
available network connections, modem connections, available input and output devices,
CDROM or other transfer media.
SECTION 6
6.0 Metadata
6.1 Federal Geographic Data Committee (FGDC) Metadata Standards
The State of Georgia has chosen to adopt the full Federal Geographic Data Committee (FGDC)
Content Standard for Geospatial Metadata, and reserves the right to add to this content standard
as necessary to accommodate the needs the citizens of the State of Georgia.
SECTION 7
7.0 Implementation Procedures
A common understanding of the standards and guidelines contained in the manual will be crucial
if the State is to achieve the goals of information integration and cost-effective GIS development.
If agencies require assistance in adhering to the standards and guidelines, the GIS Standards
Committee and Clearinghouse will be available for consultation to help determine efficient
implementation strategies.
7.1 Agency Information Resources Manager's Certification
The agency Information Resources Manager (IRM) or other agency appointed representative will
certify that GIS development in the agency adheres to these standards. This certification will be
delivered in the form of an annual report, submitted to the Clearinghouse. Instructions for
completing the report will be provided by the Clearinghouse to each agency. Agency IRM’ s
will be identified as memorandums of agreement are reached between the Clearinghouse and
agencies.
The standards compliance certification reports will provide the Clearinghouse, technical working
groups and the GIS Advisory Committee with the information needed to determine whether or
not the standards are being appropriately applied, and will ensure that agencies are using the
standards in a consistent manner. This feedback mechanism will be very beneficial as the
standards evolve and will help track the successful implementation of the standards within the
State's GIS community.
Appendix A. Standards for 1:24,000-Scale Digital Line Graphs and Quadrangle Maps:
Digital Line Graph - Enhanced
(This particular document is not yet available in digital form
but the current DLG Standards may be downloaded from the
US National Mapping Program Geospatial Data Standards on
the USGS web server.)
Appendix B. Content Standards for Digital Geospatial Metadata
(Please visit the Federal Geographic Data Committee web site to download
this standards document)
Appendix C. Georgia Base-Map Technical Working Group Membership
Jack Alhadeff, US Geological Survey
Connie Blackmon, Atlanta Regional Commission
Michael Blanchard, CSRA
Gary Daniels, Georgia Department of Transportation
Steve Davis, Georgia GIS Data Clearinghouse
Steve French, Georgia Institute of Technology
Scott Higgins, Georgia GIS Data Clearinghouse
Terry Jackson, Georgia Department of Community Affairs, BMTWG Chairperson
Tracy Leet, Georgia Department of Transportation
Rick McGee, Oglethorpe Power Company
Don Richards, Georgia Power Company
Alan Sandercock, Georgia Department of Natural Resources
Jeff Simmons, Department of Industry, Trade and Tourism
Sara Yurman, our first BMTWG Chairperson
Mike Callahan, USGS Cartographic Advisor
Ray Argo, GISAC Chairperson.
Appendix D. United States National Map Accuracy Standards
To find methods of ensuring the accuracy of both location (the latitude and longitude of a point)
and elevation (the altitude above sea level), the American Society for Photogrammetry and
Remote Sensing--an organization actively involved in the science of making precise
measurements from photographs (photogrammetry) and acquiring information from aerial
photographs and satellite image data (remote sensing)--set up a committee in 1937 to draft
accuracy specifications. Sparked by this work, agencies of the Federal Government, including
the USGS, began their own inquiries and studies of map accuracy standards. In 1941, the U.S.
Bureau of the Budget issued the "United States National Map Accuracy Standards," which
applied to all Federal agencies that produce maps. The standards were revised several times, and
the current version was issued in 1947.
United States National Map Accuracy Standards
With a view to the utmost economy and expedition in producing maps which fulfill not only the
broad needs for standard or principal maps, but also reasonable particular needs of individual
agencies, standards for published maps are defined as follows:
1. Horizontal accuracy. For maps on publication scales larger than 1:20,000, not more than
10 percent of the points tested shall be in error by more than 1/30 inch, measured on the
publication scale; for maps on publication scales of 1/20,000 or smaller, 1/50 inch. These
limits of accuracy shall apply in all cases to positions of well defined points only. Welldefined points are those that are easily visible or recoverable on the ground, such as the
following: monuments or markers, such as bench marks, property boundary monuments;
intersections of roads, railroads, etc.; corners of large buildings or structures (or center
points of small buildings); etc. In general what is well defined will also be determined by
what is plottable on a scale of the map within 1/100 inch. Thus while the intersection of
two road or property lines meeting at right angles would come within a sensible
interpretation, identification of the intersection of such lines meeting at an acute angle
would obviously not be practicable within 1/100 inch. Similarly, features not identifiable
upon the ground within the close limits are not to be considered as test points within the
limits quoted, even though their positions may be scaled closely upon the map. In this
class would come timber lines, soil boundaries, etc.
2. Vertical accuracy, as applied to contour maps on all publication scales, shall be such
that not more than 10 percent of the elevations tested shall be in error more than one-half
the contour interval. In checking elevations taken from the map, the apparent vertical
error may be decreased by assuming a horizontal displacement within the permissible
horizontal error for a map of that scale.
3. The accuracy of any map may be tested by comparing the positions of points whose
locations or elevations are shown upon it with corresponding positions as determined by
surveys of a higher accuracy. Tests shall be made by the producing agency, which shall
also determine which of its maps are to be tested, and the extent of such testing.
4. Published maps meeting these accuracy requirements shall note this fact on their legends,
as follows: "This map complies with National Map Accuracy Standards."
5. Published maps whose errors exceed those aforestated shall omit from their legends all
mention of standard accuracy.
6. When a published map is a considerable enlargement of a map drawing (manuscript) or
of a published map, that fact shall be stated in the legend. For example, "This map is an
enlargement of a 1:20,000-scale map drawing," or "This map is an enlargement of a
1:24,000-scale published map."
7. To facilitate ready interchange and use of basic information for map construction among
all Federal mapmaking agencies, manuscript maps and published maps, wherever
economically feasible and consistent with the uses to which the map is to be put, shall
conform to latitude and longitude boundaries, being 15 minutes of latitude and longitude,
7.5 minutes, or 3-3/4 minutes in size.
Source: Maps for America: Cartographic Products of the U.S. Geological Survey and Others by Morris M.
Thompson. (USGS. Third Edition 1987)
Appendix E. Supplement to Section 3.2.2, 'State Plane Coordinate Systems (1927 and
1983 datums)'.
The GIS Standards and Guidelines in the State of Georgia were adopted as a working set of
standards to be amended as new information and requirements necessitated. This appendix or
supplement was adopted on November 18, 1997 by the Data Development Technical Working
Group after subsequent research revealed a substantial body of information on the Georgia State
Plane Coordinate System in the Official Code of Georgia. The relevant sections from Title 44,
Property; Chapter 4 Determination of Boundaries; Article 2 Coordinate System, (44-4-20
through 44-4-31) were copied and provided below for quick reference:
44-4-20.
(a) The systems of plane coordinates which have been established by the National
Ocean Survey/National Geodetic Survey, formerly the United States Coast and
Geodetic Survey, or its successors for defining and stating the geographic
positions or locations of points on the surface of the earth within the State of
Georgia are hereafter to be known and designated as the "Georgia Coordinate
System" and the "Georgia Coordinate System of 1985."
(b) For the purpose of the use of these systems, the state is divided into an "East
Zone" and a "West Zone":
(1) The area now included in the following counties shall constitute the East
Zone: Appling, Atkinson, Bacon, Baldwin, Brantley, Bryan, Bulloch, Burke,
Camden, Candler, Charlton, Chatham, Clinch, Coffee, Columbia, Dodge, Echols,
Effingham, Elbert, Emanuel, Evans, Franklin, Glascock, Glynn, Greene,
Hancock, Hart, Jeff Davis, Jefferson, Jenkins, Johnson, Laurens, Liberty, Lincoln,
Long, McDuffie, McIntosh, Madison, Montgomery, Oglethorpe, Pierce,
Richmond, Screven, Stephens, Taliaferro, Tattnall, Telfair, Toombs, Treutlen,
Ware, Warren, Washington, Wayne, Wheeler, Wilkes, and Wilkinson; and
(2) The area now included in the following counties shall constitute the West
Zone: Baker, Banks, Barrow, Bartow, Ben Hill, Berrien, Bibb, Bleckley, Brooks,
Butts, Calhoun, Carroll, Catoosa, Chattahoochee, Chattooga, Cherokee, Clark,
Clay, Clayton, Cobb, Colquitt, Cook, Coweta, Crawford, Crisp, Dade, Dawson,
Decatur, DeKalb, Dooly, Dougherty, Douglas, Early, Fannin, Fayette, Floyd,
Forsyth, Fulton, Gilmer, Gordon, Grady, Gwinnett, Habersham, Hall, Haralson,
Harris, Heard, Henry, Houston, Irwin, Jackson, Jasper, Jones, Lamar, Lanier, Lee,
Lowndes, Lumpkin, Macon, Marion, Meriwether, Miller, Mitchell, Monroe,
Morgan, Murray, Muscogee, Newton, Oconee, Paulding, Peach, Pickens, Pike,
Polk, Pulaski, Putnam, Quitman, Rabun, Randolph, Rockdale, Schley, Seminole,
Spalding, Stewart, Sumter, Talbot, Taylor, Terrell, Thomas, Tift, Towns, Troup,
Turner, Twiggs, Union, Upson, Walker, Walton, Webster, White, Whitfield,
Wilcox, and Worth.
44-4-21.
(a) As established for use in the East Zone, the Georgia Coordinate System or the
Georgia Coordinate System of 1985 shall be named; and, in any land description
in which it is used, it shall be designated the "Georgia Coordinate System East
Zone" or the "Georgia Coordinate System of 1985 East Zone."
(b) As established for use in the West Zone, the Georgia Coordinate System or the
Georgia Coordinate System of 1985 shall be named; and, in any land description
in which it is used, it shall be designated the "Georgia Coordinate System West
Zone" or the "Georgia Coordinate System of 1985 West Zone."
44-4-22.
The plane coordinate values for a point on the earth's surface, used to express the
geographic position or location of such point in the appropriate zone of this
system, shall consist of two distances expressed in U.S. Survey feet and decimals
of a foot when using the Georgia Coordinate System and expressed in either
meters and decimals of a meter or, following conversion as provided in Code
Section 44-4-28, in American Survey feet and decimals of a foot when using the
Georgia Coordinate System of 1985. One of these distances, to be known as the
"x-coordinate," shall give the position in an east-and-west direction; the other, to
be known as the "y-coordinate," shall give the position in a north-and-south
direction. These coordinates shall be made to depend upon and conform to plane
rectangular coordinate values for the monumented points of the North American
Horizontal Geodetic Control Network as published by the National Ocean
Survey/National Geodetic Survey, formerly the United States Coast and Geodetic
Survey, or its successors, and whose plane coordinates have been computed on
the systems defined in this article. Any such control monument may be used for
establishing a survey connection to either Georgia Coordinate System.
44-4-23.
When any tract of land to be defined by a single description extends from one into
the other of the above coordinate zones, the positions of all points on its
boundaries may be referred to either of the two zones, the zone which is used
being specifically named in the description.
44-4-24.
(a) For purposes of more precisely defining the Georgia Coordinate System, the
following definition of the United States Coast and Geodetic Survey, now
National Ocean Survey/National Geodetic Survey, is adopted:
(1) The "Georgia Coordinate System East Zone" is a transverse Mercator
projection of the Clarke spheroid of 1866, having a central meridian eighty-two
degrees ten minutes west of Greenwich, on which meridian the scale is set one
part in 10,000 too small. The origin of coordinates is at the intersection of the
meridian eighty-two degrees ten minutes west of Greenwich and the parallel thirty
degrees north latitude. This origin is given the coordinates: x = 500,000 feet and y
= 0 feet; and
(2) The "Georgia Coordinate System West Zone" is a transverse Mercator
projection of the Clarke spheroid of 1866, having a central meridian eighty-four
degrees ten minutes west of Greenwich, on which meridian the scale is set one
part in 10,000 too small. The origin of coordinates is at the intersection of the
meridian eighty-four degrees ten minutes west of Greenwich and the parallel
thirty degrees north latitude. This origin is given the coordinates: x = 500,000 feet
and y = 0 feet.
(b) For purposes of more precisely defining the Georgia Coordinate System of
1985, the following definition by the National Ocean Survey/National Geodetic
Survey is adopted:
(1) The "Georgia Coordinate System of 1985 East Zone" is a transverse Mercator
projection of the North American Datum of 1983, having a central meridian
eighty-two degrees ten minutes west of Greenwich, on which central meridian the
scale is set one part in 10,000 too small. The origin of coordinates is at the
intersection of the central meridian eighty-two degrees ten minutes west of
Greenwich and the parallel thirty degrees north latitude. This origin is given the
coordinates: x = 200,000 meters and y = 0.000 meters; and (2) The "Georgia
Coordinate System of 1985 West Zone" is a transverse Mercator projection of the
North American Datum of 1983, having a central meridian eighty-four degrees
ten minutes west of Greenwich, on which central meridian the scale is set one part
in 10,000 too small. The origin of coordinates is at the intersection of the central
meridian eighty-four degrees ten minutes west of Greenwich and the parallel
thirty degrees north latitude. This origin is given the coordinates: x = 700,000
meters and y = 0.000 meters.
44-4-25.
No coordinates based on either Georgia Coordinate System purporting to define
the position of a point on a land boundary shall be presented to be recorded in any
public land records or deed records unless such point has been connected by
survey to a monumented horizontal control station that is identified and has been
established in conformity with the standards of accuracy and specifications as
prepared and published by the Federal Geodetic Control Committee of the United
States Department of Commerce. Standards and specifications of the Federal
Geodetic Control Committee or its successors in force on the date of said survey
shall apply. The publishing of the existing control stations, or the acceptance with
intent to publish the newly established control stations, by the National Ocean
Survey/National Geodetic Survey will constitute evidence of adherence to the
Federal Geodetic Control Committee specifications.
44-4-26.
The use of the term "Georgia Coordinate System East Zone," "Georgia
Coordinate System of 1985 East Zone," "Georgia Coordinate System West Zone,"
or "Georgia Coordinate System of 1985 West Zone" on any map, report of
survey, or other document shall be limited to coordinates based on the Georgia
Coordinate Systems as defined in this article.
44-4-27.
The term "Grid North, Georgia East Zone" refers to the fixed north direction in
the East Zone, being Geodetic North for the central meridian eighty-two degrees
ten minutes west of Greenwich. The term "Grid North, Georgia West Zone" refers
to the fixed north direction in the West Zone, being Geodetic North for the central
meridian eighty-four degrees ten minutes west of Greenwich. The applicable Grid
North term and the basis of orientation shall appear on maps of survey that are
purported oriented to a Georgia Coordinate System zone.
44-4-28.
Any conversion of distances between the meter and the American Survey foot
will be based upon the length of the meter (exactly) equals 39.37 inches or
3.2808333333 1/3 feet.
44-4-29.
Nothing contained in this article shall require any purchaser or mortgagee to rely
on a description, any part of which depends exclusively upon the Georgia
Coordinate System or the Georgia Coordinate System of 1985. Nothing in this
article shall be so construed as to require any person, firm, or corporation to use
these systems of coordinates to obtain or secure a legal description of land or real
estate.
44-4-30.
(a) Any legal description prepared under the provisions of the Georgia Coordinate
System provided by an Act approved March 6, 1945 (Ga. L. 1945, p. 218), and
continued as a part of this Code until July 1, 1985, shall not be invalid.
(b) Any continual use of legal descriptions prepared under the terms of the
Georgia Coordinate System provided by an Act approved March 6, 1945 (Ga. L.
1945, p. 218), and continued as a part of this Code until July 1, 1985, which have
been recorded or filed in official records within the State of Georgia, shall not be
invalid.
44-4-31.
The Georgia Coordinate System provided for in the Act approved March 6, 1945
(Ga. L. 1945, p. 218), shall not be used after January 1, 1990; the Georgia
Coordinate System of 1985 will be the sole system after said date.