Land Details. Bridging the Gap between Assessor Acres and GIS Acres

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Gregory Holmes
6 years ago
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1 Land Details Bridging the Gap between Assessor Acres and GIS Acres

2 What are Assessor Acres? It is a legally agreed upon approximation of size Applies to larger parcels Has deep historical roots. Thomas Jefferson

3 GIS vs Assessor Acres Assessor Acres Legally defined area Fixed area Absolute precision Users: Legislature Assessors Planners Citizens

4 GIS Acres vs Assessor Acres GIS Acres Assumes the world is flat Measurable accuracy in x and y Area changes to accommodate spatial accuracy Users: GIS

5 Common Misconceptions GIS area is more accurate GIS Area is different Using GIS area would make things easier Legal areas are fixed GIS polygons are not fixed size

6 Analogous to a Linear Reference System (LRS) An LRS route can have user defined length Events are placed with respect to the defined length. A Parcel can have a user defined area Sub polygons can be mapped with respect to the defined Area

7 Assessor Acres Applications Current Use Application Areas Assessor Easements Senior Exemptions One Acre Homesites Market Value Calculations Automated Splits/Merges

8 Sample Parcel 1 Acre Homesize.55 Acre Natural Gas Easement Acre Current Use Application Total Assessor Acres Total GIS Acres Factor: / =

9 Land Detail Layer Sample Parcel

10 Mapping in Assessor Acres Homesite Area: * = 43560

11 Land Detail Market Value Layer Based on: Slope, Wetlands, Easements, Homesite

12 Market Value Calculation GIS Acres * Factor * Market Value Type Rate Per Acre

13 Current Use Value Layer Based On Soil Types

14 Current Use Value Calculation GIS Area * Factor * Soil type Rate Per acre

15 Appraisers Role Interface between Policy and Public Did you take my wetland, cliff, easement into consideration?

16 Appraiser / Public Generalizations Slopes Includes Low or wetland Easements May not be a recorded easement. Areas Approximate but set in stone

17 Easements: Easements

18 Old School: 2 Sets of books Maintained Manually Totals Must Balance Easements, Wetlands deducted from Flat or Rolling

19 Mapping Benefits Easements No longer lost in the database Can visualize errors, inconsistencies No longer automatically deducted from high value land Slopes and Soils can use GIS Lidar Wetlands Inventory/Model

20 GIS Mapping Challenges How do you create polygons of a predefined size? Real Time Layer Maintenance In synch with Assessors Database Acreage adjustments Easement Add/Drops In synch with GIS Parcels Layer Parcel edits: Fitting new subdivisions In synch with Current Use Layer

21 Editing Land Details Place a seed feature: Point, Line, Poly Grow the feature to the correct size Adjust other features to accommodate the new polygon.

22 Homesite Seed

23 New 1 Acre Homesite

24 Easement Seed 2.5 Acre Easement

25 New Easement Homesite moved

26 Maintenance Parcel Splits and Merges Boundary Line Adjustments Assessor Acreage Correction Add, Drop, edit of easements

27 Requirements Keep layers in synch with Assessor database Keep Assessor database in synch with layers Keep it simple

28 Land Detail Worksheet

29 Assessor Database GIS Layer

32 Split Merge

36 LandDetail Wizard Summary Spreadsheet / Wizard interface Automatically applies most changes to map layers Updates GIS Layers Land Detail Land Detail Market Value Current Use Value Updates Assessor s Database

37 Current Use Mapping based on tree lines, fields Acreage based on application Applications persist when parcels are split One Parcel can have multiple applications One Application can include multiple parcels

41 Conclusions Mapping by area is pretty cool Presents new ways of viewing information Simplifies, standardizes, automates many Assessment tasks Bridges the gap between legal areas and GIS based areas

GOVERNMENT. Case Study Ville de Trois Rivières streamlines property assessment

GOVERNMENT. Case Study Ville de Trois Rivières streamlines property assessment GOVERNMENT Case Study Ville de Trois Rivières streamlines property assessment GIS-generated parcel basemap provides powerful visualization & analysis capabilities With a population of just over 130,000,