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Ann Arbor GIS Metadata

Extended Parcel Features

Category Administrative/Ownership Data Base
Name .prcl_ext
Type Library Layer
Abstract The Cadastral Base or Real Estate Atlas Program (REAP) data is comprised of two related components; Basic Parcel features consisting of current property boundaries and identifications, and Extended Parcel features consisting of historic property boundaries and additional details required in the creation of traditional Assessor Parcel maps. These related features are extremely important and provide the foundation for many subsequent GIS data layers.
Maintenance Maintenance of City property information continues using the "Parcel Maintenance System" developed in Arc Macro Language (AML) by ITSD for use by Assessor staff. Configuration of Librarian tiles changed from Neighborhood to Section based structure in 1998 for simplication of maintenance procedures. Future plans include acquiistion of new County parcel data.
Source Large-Scale GIS Data Base Development Part C (1995) and Update (1997) Projects
Agency/Contact Finance Department Assessing Division / rdoletzky@ci.ann-arbor.mi.us
Accuracy National Map Accuracy Standards for 1"=100', 1:1200, 1-2 foot positional accuracy
Projection NAD83 State Plane, Michigan South Zone 6401
Units US Survey Feet
Spheroid GRS1980
Domain Quarter Sections within the Large-Scale GIS Data Base Update Project Area
Format Double Precision Link Coverage EXTD_COV; Points and Arcs with INFO attributes
Tiles 167 tiles approximating Quarter Section boundaries
Count 16730 Points -11758 Arcs - 8 Annotation Subclasses
Count Anno Subclass Count Anno Subclass Count Anno Subclass Count Anno Subclass
25017 ADDR 391 PLACE 97 NOTES 3113 ROWS
100588 DIMS 24285 LOTS 1789 SNAM 85 VROWS
Qualifications City Assessor and County Equalization property maps were converted for each quarter section within the Large Scale Data Base Development and Update Project Areas. Source maps were audited, and changes occurring during conversion process were trapped and integrated. The general procedure for converting the ownership information included assembling individual Assessor Blocks using "Coordinate Geometry" and registration of those individual Assessor Blocks with features identifiable on a Digital Orthophoto background.
Qualifications Accurate content and current nature of the Parcel data is now very good due to Assessor staff maintaining their own GIS data layers, while County inholding information remains static until the new County parcel data is available.

Inconsistencies can be detected regarding the symbolization of orginal lot lines and current property lines due to changes that occurred to the data base design.These inconsistencies are being corrected as time allows.

EXTD_COV.PAT - Point Attribute Table Definition and Content

Column Field Name Width Output Type N Dec Alt Name Indexed? Field Content
1 AREA 8 18 F 5   - Point Area (square feet)
9 PERIMETER 8 18 F 5   - Point Perimeter (feet)
17 EXTD_COV# 4 5 B -   * Point Internal ID
21 EXTD_COV-ID 4 5 B -   - Point User Assignable ID
25 BLOCK 3 3 C -   - Assessor Block Number
30 KFEAT 4 6 B -   - Symbolization Code

EXTD_COV.AAT - Arc Attribute Table Definition and Content

Column Field Name Width Output Type N Dec Alt Name Indexed? Field Content
1 FNODE# 4 5 B -   - From Node Internal ID
5 TNODE# 4 5 B -   - To Node Internal ID
9 LPOLY# 4 5 B -   - Left Polygon Internal ID
13 RPOLY# 4 5 B -   - Right Polygon Internal ID
17 LENGTH 8 18 F 5   - Arc Length (feet)
25 EXTD_COV# 4 5 B -   * Arc Internal ID
29 EXTD_COV-ID 4 5 B -   - Arc User Assignable ID
33 KFEAT 4 6 B -   - Symbolization Code