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Ann Arbor GIS Metadata

Basic Parcel Features

Category Administrative/Ownership Data Base
Name .prcl_bsc
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 City Assessor staff. Configuration of Librarian tiles changed from Neighborhood to Section based structure in 1998 for simplication of maintenance procedures. Future plans include interfacing with SQL tables and acquisition 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 Network Coverage BASC_COV; Polygons with INFO attributes and related SQL table AAUIS.LPIN, and Arcs with INFO attributes
Tiles 167 tiles approximating Quarter Section boundaries
Count 26260 Polygons - 74724 Arcs
Qualifications City Assessor and County Equalization property mapping was converted for each quarter section within the Large-Scale GIS 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 property 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.

MCD Codes (Minor Civil Division) are necessary due to a limited number of City/County duplicate parcel identifications within the Project Area.

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

BASC_COV.PAT - Polygon Attribute Table Definition and Content

Column Field Name Width Output Type N Dec Alt Name Indexed? Field Content
1 AREA 8 18 F 5   - Polygon Area (square feet)
9 PERIMETER 8 18 F 5   - Polygon Perimeter (feet)
17 BASC_COV# 4 5 B -   * Polygon Internal ID
21 BASC_COV-ID 4 5 B -   - Polygon User Assignable ID
25 LPIN 10 10 C -   - Land Parcel Identification Number
30 TAG 4 4 C -   - Assessor Parcel Extension
34 ERROR 4 4 C -   - Error Flag
38 MCD_CODE 3 3 C -   - Minor Civil Division
41 IMAGE_NUM 2 2 I -   - Attached Image Count

BASC_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 BASC_COV# 4 5 B -   * Arc Internal ID
29 BASC_COV-ID 4 5 B -   - Arc User Assignable ID
33 KFEAT 4 6 B -   - Symbolization Code