Enhancing Parcel Data In Colleton County. February 10, 2009

Size: px

Start display at page:

Download "Enhancing Parcel Data In Colleton County. February 10, 2009"

Laureen Manning
5 years ago
Views:

1 Enhancing Parcel Data In Colleton County GIS & CAMA Conference February 10, 2009

2 Introductions Bruce T. Harper Technology Director Colleton County, SC Bill Wetzel National GIS Account Manager The Sidwell Company

3 Today s Agenda Colleton County GIS Reviewing i Parcel Data GIS Conversion Project Questions

4 Enhancing Parcel Data in Colleton County, SC Colleton County GIS Overview

5 Colleton County GIS County Statistics Low Country Coastal Region - Over 1,000 sq. miles - Approx. 40,000 Population - Approx. 39,000 Parcels

6 Colleton County GIS County Expectations of GIS Manager Overall Assessment Work Flow Parcel Splits & Combines Up to date Tax Maps Data What do we have? Is it reliable? Where did it originate from?

7 Colleton County GIS 2003 Aerial Photography Statewide Project through the South Carolina Geodetic Survey Group Became the foundation for establishing a GIS

8 Colleton County GIS Paper Maps to Geodatabase RFP for conversion project (2004) Firm chosen (Best Fit Method) Rubber sheeting process Common practice for first time GIS conversion projects (getting their foot in the GIS door) Supportive of the Parcel mapping

9 Colleton County GIS Legacy conversion issues Scanned mylar maps Page by page system Warped to best fit imagery Spatial accuracy is compromised Inconsistent fit Geometry altered by warping Can complicate updating the GIS Parcels only Full cadastral GIS contains more detail

10 Enhancing Parcel Data in Colleton County, SC Reviewing i Parcel Data

11 Reviewing Data How and when was it constructed? What was the source?

12 Reviewing Data How was it maintained? Platform or format conversion?

13 Reviewing Data Data Model Polygon Linear Content Simple shapes Robust feature classes Annotation Cartographic features

14 Source Documents

15 Imagery

16 Dimensions

17 Dimensions

18 Tapering ROWs

20 Enhancing Parcel Data in Colleton County, SC Building Support

21 Colleton County GIS Parcel Boundary Discrepancies Outside the center of the Tax Map Very common along Tax Map edges (Edge Matching) Looked as if the property boundary went through building structures (Homes)

22 Colleton County GIS Why The Need Departments t that t may be (are) affected by inaccurate data Assessor Planning & Development Economic Development E911 Fire & Rescue Emergency Preparedness Department More accurate data, allows for better decision making Referenced to State Plane Coordinates (NAD 1983 feet) Use control points (established by State Geodetic Survey Group)

23 Colleton County GIS Parcel Fabric (Cadastral) Conversion Executive Buy In Administrator, Department Heads Commitment to convert all (not portions) Additional tools for editing and maintaining database Contract awarded (Sidwell)

24 Assessment of Your Needs Need for increased accuracy County uses All county departments should rely on the data Accurate data produces accurate analysis Public confidence Hard copy maps and/or web deployment Ease of maintenance Add cartographic elements Subdivision and lot data Increase amount of annotation

25 Enhancing Parcel Data in Colleton County, SC GIS Conversion Project

26 Colleton County Project Establish geodatabase design Define workflows Identify any bottlenecks Propose solutions Define needs Chose best model Customize where needed Create prototype design County review and acceptance

27 Cadastral Data Model Tagged data model Makes maintenance of GIS more efficient Supports powerful data analysis Easy data deployment Ensures coincident boundaries

28 Traditional Layering vs. Tagged Model Features on top of features on top of features Can result in this Topology rules will help the exceptions are everywhere

29 Traditional Layering vs. Tagged Model One geometry with multiple definitions OID Tag 214 Lot 214 Parcel 214 ROW 214 Subdivision Ensures consistency between layers, because all layers are generated from the same geometry

30 Tagged Data Model

31 Colleton County Project Data collection Some of the documents are digital Sidwell staff will capture the remaining documents needed on site High resolution digital capture Safe for old fragile documents All captured information o is delivered e ed

32 Colleton County Project Reengineering the cadastral fabric From the ground up approach The giant jigsaw puzzle Use all available plats and surveys Estimated that 22,717 parcels have a plat reference in tax system COGO subdivision plats and surveys Draw using the provided geometric information and fully annotate

33 Colleton County Project Place subdivision plats into GIS fabric Verify fit to imagery Slight rotation maybe necessary Use road and railroad ROW plats to help tie the fabric together Add parcels from survey plats Use geometric construction whenever possible Verify fit to the subdivision plats and imagery Use road and railroad ROW plats to help tie the parcels into the GIS fabric

34 Colleton County Project If documents are not available Rely on existing dimensions Rework existing line work based on existing dimensions Work off tied down parcels (where documentation exists) If no documents or dimensions exist, rework the line work to better fit the imagery The smallest percent of the parcels Use tax roll for parcel inventory Verify every parcel mapped

35 Colleton County Project Request additional information as needed When parcels conflict and additional information is needed for resolve Extend the Tagged Data Model by adding other features Hydrology (as located on the ground) Roads (where plats don t exist) Railroads (where plats don t exist) Corporate boundaries Feature linked annotation

36 Colleton County Project Digital images of Subdivision plats will be linked to the GIS

37 Colleton County Project Resolving discrepancies in land records Review all source documentation Newest documents usually have highest priority Lock down proven lines and points first Isolate problems to the smallest area possible Look to the aerial imagery to prove that t your decisions are correct Sometimes the document is incorrect and the aerial image is the only way to prove it Experienced mappers identify, question, and research discrepancies

38 Colleton County Project Discrepancy Notes Notation to indicate any problems, oddities, or items that may require further attention

39 New Parcel Numbers Assigning the Permanent Parcel Number The parcel number consists of 10 digits as follows: XXX XX XX XXX Group 1 Group 2 Group 3 Group 4 Group 1: Three (3) digits designate a grid number Group 2: Two (2) digits designate the quarter of the grid 01 Northwest, 02 Northeast, 03 Southwest, 04 Southeast Group 3: Two (2) digits (only used in urban areas) designate block number broken down by quartering the quarter of the grid. Group 4: Three (3) digits designate the parcel numbers.

40 New Parcel Numbers

41 New Parcel Numbers Parcel Number Grid Number 02 Quarter Gird Number 00 Rural Parcel 28 Ub Urban Block Number 006 Parcel Number Northeast QuarterofBlock Blocks Blocks Blocks Blocks

42 Quality Control Quality Control Mechanisms Enforcement of Data Capture Rules Feature tagging lines No duplicate lines First Map Check All compiled map work is reviewed All source documents are checked against the map Linework is checked against the aerial imagery All text is verified Tax Roll is reread and verified to the map Discrepancy Reports are reviewed Etc.

43 Quality Control Digital Verification Check all line features Topology Database Processing and Linkage Check Parcel polygon to tax roll validation Tax roll to parcel polygon validation Check Discrepancy Reports for valid mismatches Data Discrepancy Research Confirm that all research has been requested, received and is correct Map conflicts are reported in Discrepancy Reports

44 Quality Control Pre-delivery Final Quality Check Use the power of the GIS software to check for errors Over 20 queries are run on the geodatabase prior to delivery Post Delivery Assurance We stand behind our products 100% All work will be completed at Sidwell! County QC Working together to ensure the best possible GIS No time limit for Sidwell corrections

45 Conclusion AC County GIS(Improvements) Driver (Assessor s Cadastral Data) Conversion Project Award Contract and move forward

46 Questions?

47 THANK YOU! Bruce T. Harper Technology Director Colleton County, SC Bill Wetzel National GIS Account Manager The Sidwell Company

MAPPS 2012 Geospatial Products and Services Excellence Awards Awards Entry Form

MAPPS 2012 Geospatial Products and Services Excellence Awards 2012 Awards Entry Form Please include a copy of this document with the project/product submission Entry Information Submission Number: 1741558