PROPOSED ACTIVITIES
The Contractor will:
1. Provide all necessary personnel, equipment, and facilities required to produce hydrography to USGS DLG-F standards.
2. Provide completed DLG-F datasets to the Georgia GIS Data Clearinghouse for review and acceptance. The following ESRI coverages will be provided for each county listed in the delivery schedule:
a. wetlands
b. rivers
3. Adhere to the “Geographic Information Systems Standards and Guidelines for the state of Georgia.”
4. Adhere to the feature content documented in the National Mapping Program’s Technical Instructions, Part 2 Hydrography, “Standards for Hydrography Dataset – High Resolution,” with modifications approved by the Data Development TWG.
5. Submit quarterly progress reports summarizing base map activities.
The ITPC will:
1. Provide to the Contractor on request current versions of all relevant standards.
BACKGROUND
In March 1996 the Information Technology Policy Council (ITPC) created the Geographical Information System Advisory Committee (GISAC) to advise the Council on various GIS related issues. Soon thereafter GISAC assigned technical working groups composed of representative GIS users from key agencies, regional councils, the university system and public utilities. The Base-Map Technical Working Group (BMTWG), currently known as the Data Development Technical Working Group (DDTWG) set out to identify the required initial base-map layers and to identify and adopt a set of initial statewide base-map and GIS standards.
The BMTWG recognized early that the state would realize the greatest benefit by directing it's existing base-map development programs toward compliance with those of the established national mapping programs and standards. Since the U.S. Geological Survey (USGS) is by law the lead mapping agency of the federal government, the Group sought consultation and authoritative advice from the USGS National Mapping Program advisors. The Group reviewed and unanimously adopted the USGS Digital Line Graph (DLG-F) standard for base-map development. The DLG specification has been the vector data model standard of the U.S. National Digital Cartographic Data Base for over ten years. DLG-F is the prototype of the next generation of this standard and Georgia will be one of the first states to enjoy it's many refinements that will support computer aided mapping and GIS-based decision support systems.
The BMTWG explored various potential collaborative agreements whereby the state could develop GIS base maps while sharing cost and effort with the USGS. The benefits of entering into such an agreement are numerous; the five principle benefits are:
_ It affords the state an opportunity to realize an
immediate return on its investment in the existing statewide mapping programs,
such as the Georgia Department of Transportation base maps, while moving toward
a national standard.
_ Agencies could begin
immediately to develop other map and data layers registered to the Digital
Orthophoto Quadrangle 1:12,000 base and to the DLG-F coding standard.
This process would provide a clear migration path for
moving these layers to the DLG-F standard without having to wait until the
base-map development project is completed.
_ Adoption and publication of national mapping and GIS standards by the state will guide the common development of both government and private sector spatial information systems which will foster informed decision making for economic development.
_ Establishing a state standard that is compliant with the National
Spatial Data Infrastructure (NSDI) and other federally sponsored initiatives
would bring Georgia onto the national scene. Compatibility with similar
federally based standards in bordering states would also allow for data sharing
at a regional level, while gaining a more competitive advantage through its
information resources.
_ GIS development would be enhanced as a direct result of being able to rely on geographic data.
TECHNICAL ABSTRACT
When the Georgia DOT started a digital mapping program in 1993, it was recognized that the Department’s General Highway Map Series (county based) and City Map Series, which were created and maintained at 31,680 and 7,920 scales, were the best map sources available for the routes that make up the state’s roadway system. The maps contained temporal updates to the road system, which had been originally derived from USGS 7.5 minute quadrangles and also contained route identification numbers (RCLINK) and origins with respect to the field collected route attributes. When these maps were digitized, care was taken to assign the proper orientation and identification to each route. Now, each route in the digital road layer can be linked to the Department’s Road Characteristics Database, which contains a linear reference for the different route features, attributes and conditions. The Department currently integrates updates to city limit boundaries, cultural features, and federal and state property boundaries in the digital base map.
Initial digitization of county level transportation and boundary map features was performed using ESRI’s Arcedit software and Altek’s Datatab high accuracy digitizing tablets from the County Series published at 1:31,680-scale on mylar. City level transportation and boundary features were digitized from the City Series published at 1:7,920-scale on mylar. A minimum of 8 registration points were used to register source maps to the digitizer. Coverages were plotted to scale and overlaid on the source mylar for QA/QC of the original digitization. Once digitized, county based map features were edge-matched to adjacent counties using Arcedit’s snapping and link adjustment utilities and added to the digital map library. The city based map features were edge matched and merged with the county. Since that time, road updates have been added using 2 methodologies; (1) manually digitized on-screen using a USGS Digital Orthophoto Quarter Quadrangle (DOQ) base, and (2) integration of GPS road centerline data. The Department took a different approach for compiling the statewide hydrography layer. The hydrographic features represented on the Department's original County and City Map Series reflected only a subset of the content available from the 1:24,000-scale USGS quadrangles and the decision was made to capture statewide hydrography from the quadrangle base instead of the Department’s maps. Mylar color quadrangle separates were purchased from the USGS, scanned, vectorized, georeferenced, edge matched, tiled by county, and added to the digital map library. QA/QC has been performed by both the Cartographic Unit of the Georgia Department of Transportation and mapping staff at the Office of Information Technology Outreach Services, University of Georgia.
Georgia has since acquired statewide DOQ coverage in cooperation with the USGS. By using DOQ imagery, features in the digital map library can adjusted from the 1:31,680-scale feature representation to the 1:12,000-scale DOQQ image. With these resources available, the state now looks ahead to an Innovative Partnership with the USGS to photo-revise and update the feature and attribute content for the core base map.
Technical
Description of Wetlands vector data
Abstract - County tiled polygons and lines representing lakes, ponds, islands, reservoirs, and swamps/marshes. Feature capture conditions and conventions will be in accordance with the National Mapping Divisions "National Hydrography Dataset".
Source Graphic - Original digitization from USGS “blue layer” color separates (1:24,000-scale mylar source document). Photo-revision to 1993 USGS Digital Orthophoto Quarter Quadrangles (1:12,000-scale digital image) will been performed for some features in the Wetlands layer. The approximate horizontal accuracy of photo-revised features is 33.3-ft., assuming the source imagery meets National Map Accuracy Standards for 1:12,000. Features which have not been photo-revised have an approximate horizontal accuracy of 40-ft., assuming the USGS color separates meet National Map Accuracy Standards for 1:24,000. All feature coordinates are stored in Decimal Degrees.
Feature Content - Table 1 summarizes the feature content, definition, topology, and attribute coding scheme for the features present in the Wetlands layer.
|
Feature Name |
Feature Definition |
Feature Class |
Feature Extraction from Arc/Info |
Feature Attributes |
|
Island |
Area
of land surrounded by water |
Area |
Coverage: Wetlands Attribute Table: Wetlands.pat Selection Criteria: FEATURE = Island |
Name Photorevision
Category Date |
|
Lake/Pond |
A
standing body of water with a Predominantly natural shoreline surrounded by
land. |
Area |
Coverage: Wetlands Attribute Table: Wetlands.pat Selection Criteria: FEATURE = Lake/Pond |
Name Photorevision
Category Date |
|
Reservoir |
A
constructed basin formed to contain water or other liquids. |
Area |
Coverage: Wetlands Attribute Table: Wetlands.pat Selection Criteria: FEATURE = Reservoir |
Name Photorevision
Category Date |
|
Stream/River |
A
body of flowing water |
Area |
Coverage: Wetlands Attribute Table: Wetlands.pat Selection Criteria: FEATURE = Stream/River |
Name Photorevision
Category Date |
|
Swamp/ Marsh |
A
noncultivated, vegetated area that is inundated or saturated for a
significant part of the year. The
vegetation is adapted for life in saturated soil conditions. |
Area |
Coverage: Wetlands Attribute Table: Wetlands.pat Selection Criteria: FEATURE = Swamp/Marsh |
Name Photorevision
Category Date |
Table
1: Wetlands layer feature summary
Wetlands layer data
processing summary
Historical - Original mylar, 1:24,000-scale “blue layer” color separates were scanned at 400dpi resolution with an Intergraph Eagle large format scanner. Initial vectorization was performed using GENASYS’ Genarave raster to vector conversion software. Features were later converted to ESRI’s Arc/Info (Solaris versions 6.x through 7.x) software. The Wetlands layer was initially registered to Geographic Coordinates and later projected to UTM NAD83 meters with respect to the appropriate UTM zone (16 or 17 in Georgia).
Arc/Info coverages were plotted to scale and overlaid on the source mylar for QA/QC of the original vectorization. 7.5 Minute Quadrangle tiled coverage features were edge-matched to adjacent features using Arcedit snapping and link adjustment utilities. QA/QC has been performed by both the Cartographic Unit of the Georgia Department of Transportation and mapping staff at the Office of Information Technology Outreach Services, University of Georgia. The QA/QC process relies heavily on scale check-plotting and on-screen visual examination of feature attributes and alignment using Arcview 3.0. Coverages are in Arc/Info 7.04 double precision format.
Proposed - Under this agreement, shorelines of waterbody features in the Wetlands layer will be adjusted from the 1:24,000-scale feature representation to the 1:12,000-scale DOQQ image utilizing rules outlined in the USGS’ NMD Technical Criteria for Digital Revision and Product Generation: 1:24,000-Scale Digital Line Graphs and Quadrangle Maps. Feature updates, which were excluded in previous DOT updating efforts, will be added to reflect the content of the DOQs. In the update process, new features will digitized on-screen using a USGS Digital Orthophoto Quarter Quadrangle base. Existing water body features will be photo-revised by digitizing the feature from the photography. QA/QC will be performed by both the Office of Information Technology Outreach Services, University of Georgia, and the USGS. The QA/QC process will rely heavily on 1:24,000-scale checkplots and on-screen visual examination of feature attributes and alignment using Arcview 3.0. Metadata for the Wetlands layer will document specifically which digital capture and/or update methodology was utilized for a given Wetlands feature.
Technical
Description of River vector data
Abstract - County tiled lines representing rivers, streams, shorelines, watercourses and artificial flow paths. Feature capture conditions and conventions will be in accordance with the National Mapping Divisions "National Hydrography Dataset". Features in the River layer will be part of a contiguous line network.
Source Graphic - Original digitization from USGS “blue layer” color separates (1:24,000-scale mylar source document). Photo-revision to 1993 USGS Digital Orthophoto Quarter Quadrangles (1:12,000-scale digital image) will be performed for some features in the River layer. The approximate horizontal accuracy of photo-revised features is 33.3-ft., assuming the DOQ imagery meets National Map Accuracy Standards for 1:12,000. Features which will not be photo-revised have an approximate horizontal accuracy of 40-ft., assuming the USGS color separates meet National Map Accuracy Standards for 1:24,000. All feature Coordinates are stored in Decimal Degrees.
Feature Content - Table 2 summarizes the feature content, definition, topology, and attribute coding scheme for the features present in the River layer.
|
Feature Name |
Feature Definition |
Feature Class |
Feature Extraction from Arc/Info |
Feature Attributes |
|
Artificial
Path |
A
known, but nonspecific, connection between two nonadjacent network segments. |
Line |
Coverage: River Attribute Table: River.aat
Selection Criteria: FEATURE = Artificial Path |
Name Artificial
Path Type Photorevision
Category Date |
|
Shoreline |
A
naturally occurring line of contact between a body of water and the
land. Georgia’s shoreline is represented
as a mean high water level. |
Line |
Coverage: River Attribute Table: River.aat
Selection Criteria: FEATURE = Shoreline |
Shoreline
Type Photorevision
Category Date |
|
Stream/ River |
A
body of flowing water. |
Line |
Coverage: River Attribute Table: River.aat
Selection Criteria: FEATURE = Stream/River |
Name Photorevision
Category Date |
Table
2: River layer feature summary
River layer data
processing summary
Historical - Original mylar, 1:24,000-scale “blue layer” color separates were scanned at 400dpi resolution with an Intergraph Eagle large format scanner. Initial vectorization was performed using GENASYS’ Genarave raster to vector conversion software. Features were later converted to ESRI’s Arc/Info (Solaris versions 6.x through 7.x) software. The River layer was initially registered to Geographic Coordinates and later projected to UTM NAD83 meters with respect to the appropriate UTM zone (16 or 17 in Georgia). Coverages were plotted to scale and overlaid on the source mylar for QA/QC of the original vectorization. 7.5 Minute Quadrangle tiled coverage features were edge-matched to adjacent features using Arcedit snapping and link adjustment utilities. QA/QC has been performed by both the Cartographic Unit of the Georgia Department of Transportation and mapping staff at the Office of Information Technology Outreach Services, University of Georgia. The QA/QC process relies heavily on 24,000-scale check-plotting and on-screen visual examination of feature attributes and alignment using Arcview 3.0. Coverages are in Arc/Info 7.04 double precision format.
Proposed - Under this agreement, shorelines of river features in the River layer will be adjusted from the 1:24,000-scale feature representation to the 1:12,000-scale DOQQ image utilizing rules outlined in the USGS’ NMD Technical Criteria for Digital Revision and Product Generation: 1:24,000-Scale Digital Line Graphs and Quadrangle Maps. Stream/River features depicted as single centerlines at 1:24,000-scale will not be photo-revised. Feature updates, which were excluded in previous DOT updating efforts, will be added to reflect the content of the DOQs. In the update process, new features will digitized on-screen using a USGS Digital Orthophoto Quarter Quadrangle base. Existing features will be photo-revised by digitizing the feature from the photography. QA/QC will be performed by both the Office of Information Technology Outreach Services, University of Georgia, and the USGS. The QA/QC process will rely heavily on 1:24,000-scale check plots and on-screen visual examination of feature attributes and alignment using Arcview 3.0. Metadata for the River layer will document specifically which digital capture and/or update methodology was utilized for a given feature.
Delivery Schedule
|
County Name |
Delivery Date |
Georgia DOT
District Number |
Quad-area (7.5
Minute quadrangles contained within the county line. |
|
dawson |
31-Oct-98 |
1 |
3 |
|
lumpkin |
31-Oct-98 |
1 |
5 |
|
union |
31-Oct-98 |
1 |
5 |
|
hancock |
31-Oct-98 |
2 |
8 |
|
taliaferro |
31-Oct-98 |
2 |
3 |
|
butts |
31-Oct-98 |
3 |
3 |
|
henry |
31-Oct-98 |
3 |
5 |
|
spalding |
31-Oct-98 |
3 |
3 |
|
calhoun |
31-Oct-98 |
4 |
4 |
|
clay |
31-Oct-98 |
4 |
3 |
|
montgomery |
31-Oct-98 |
5 |
4 |
|
telfair |
31-Oct-98 |
5 |
7 |
|
wheeler |
31-Oct-98 |
5 |
5 |
|
dade |
31-Oct-98 |
6 |
3 |
|
walker |
31-Oct-98 |
6 |
7 |
|
douglas |
31-Oct-98 |
7 |
3 |
|
gwinnett |
31-Oct-98 |
1 |
7 |
|
columbia |
31-Oct-98 |
2 |
5 |
|
mcduffie |
31-Oct-98 |
2 |
4 |
|
warren |
31-Oct-98 |
2 |
5 |
|
coweta |
31-Oct-98 |
3 |
7 |
|
fayette |
31-Oct-98 |
3 |
3 |
|
Total County Based Quadrangle Equivalents |
102 |
||
|
HUC ID 3070101 |
30-June-98 |
NA |
47 |
|
Total Hydrography Quadrangle Equivalents |
149 |
||