GIS Library Data Development
Generalized Technical Specifications for Vector Data
These technical specification elements are specific to the St. Johns River
Water Management District GIS environment. They were developed in reference
to the Mapping and Geographic Information System Standards and Conventions
Committee's Mapping and GIS Standards Report,
October 1993. Only a subset of the listed elements are appropriate for
any given GIS data development effort. The necessary subset is to be determined
by District staff responsible for developing GIS data. Information Resources
Department, GIS Program Management Division staff can be consulted for
assistance in determining which elements are necessary for a given GIS
data development effort, but final responsibility for the data definition
lies with the project manager.
Documentation
Complete and correct FGDC compliant documentation must accompany the
geospatial dataset.
Positional Accuracy
All coordinates shall be in the Universal Transverse Mercator (UTM)
projection, zone 17, referenced to the North American Datum (NAD) of 1983,
1990 adjustment.
Where appropriate, all data shall be tiled by NAD83 USGS quadrangle
boundaries
Projection information must be present and correct in each coverage
projection file and be accessible through the Arc command DESCRIBE.
Define the maximum allowable RMS error for source document registration
(0.003 - 0.008, depending on source data accuracy, medium, etc.). Actual
RMS value for each coverage shall be noted. If the defined RMS value
cannot be met, a note explaining why must accompany the coverage.
TIC x,y coordinates must match their respective registration coverage
TIC x,y coordinates exactly.
When more than one data layer is required for the end product, the
coverages' respective TIC ids and x,y coordinates must match each other
and the registration coverage exactly.
All point features shall be located at the center of the symbol or
feature on the source document which depicts the feature.
Line features must be converted within one-half feature width of the
feature represented on the source document (no daylight criterion).
Attribute Accuracy
The attribute tables must contain their ARC/INFO coverage default items
and contract specified items in the correct order and be defined correctly.
There shall be no superfluous attribute tables
All attribute items shall be defined correctly
All attribute items shall exist in the specified order
There shall be no superfluous attribute items
All items shall be coded correctly
Logical Consistency
- All files must import from ARC/INFO EXPORT format files correctly
- No edit masks shall be present
- Coverages shall exist in DOUBLE precision
- Correct topology (POINT, ARC, POLYGON, LINK, NET, ROUTE, REGION topology)
shall be present
- During the entire data development process, the ARC/INFO CLEAN routine
shall not alter any feature components so that they do not meet the specified
positional accuracy characteristics.
- Tolerance values for completed coverages shall be set to:
- Fuzzy 0.0001
- Dangle 0.0001
- Tic Match 0.0001
- Edit 1/100 of the greatest distance defined in the coverage .BND file
- Node Snap 0.0001
- Weed 0.0001
- Grain 0.0001
- Snap 0.0001
- All coverages shall be flawlessly coordinate edgematched to adjacent
coverages so that a MAPJOIN and DISSOLVE will leave no edgematching,
coding, or data capturing errors. Since product development often occurs
in partial sets of coverages, each subsequent set shall be flawlessly coordinate
edgematched to all previous sets.
- In case the source documents do not edgematch, the data developer shall
notify the source document developer for resolution.
- Contiguous, identically coded polygons shall not exist.
- Coding combinations which by proximity or definition comprise a logical
inconsistency in reference to real-world features shall not exist (this
occurence represents attribute miscoding and/or feature mapping errors).
- All features shall exist wholly within the registration coverage tile
bounding arcs.
- No superfluous pseudo nodes shall exist.
- No superfluous tics shall exist.
- There shall be no duplicate features.
- No erroneous sliver polygons shall exist.
- No label errors shall exist.
- The universe polygon shall not possess a label.
- No dangle errors shall exist.
- No intersection errors shall exist.
- Any errors as defined here-in which occur as a result of the CLEAN
process must be rectified prior to coverage completion.
Completeness
The final product shall only be described as complete and fully accepted
when all of the contract criteria are met. The completeness report shall
include descriptions of the:
relationship between the objects represented and the abstract universe
of all such objects
exhaustiveness of the spatial and taxonomic properties of the objects
in the data set (were all kinds accounted for? were all specified features
captured?)
descriptions of the procedures used for testing, the test dates, and
the test results