March 14, 2007 First Steps For Starting Your Parcel Database: Aurora Case Study Indiana GIS Conference Dearborn County GIS Ileana Abot

March 14, 2007 Outline Outline  Overview  Main Task - problems  Method/alternative selected  different methods - comparison  Experience/conclusions

March 14, 2007 Overview Overview  Hired by Dearborn County in June, 2006  help on daily requests for GIS: Maps, Data  Continue working on Aurora Zoning Map  Collaborate with County Historic Structures Project Structures Project  Collaborate with County Historic Structures Project Structures Project  Participate on GIS Task Force Meetings

March 14, 2007 City of Aurora City of Aurora  S.E. of Dearborn Co.  Population: almost 4,000 ha.  Incorporated community

March 14, 2007 Zoning Map Zoning Map

March 14, 2007 Main Task Main Task  Started working on Zoning Layer  Software: Worked with ArcEditor  Existent Parcel Layer (historic district)  Edited Existent Zoning Draft  Needed more accurate data

March 14, 2007 First Problem First Problem  Lack of Parcel data  BOUNDARIES ???

March 14, 2007 First Problem First Problem  BOUNDARIES ???  Parcels 100 Ft. off

March 14, 2007 First Decision First Decision  Start working on Parcel Layer  assign parcel project for whole county  Select from available methods  Choose existent layers for reference  Gather all useful data (digital, maps)

March 14, 2007 Methods Methods  Vary on Accuracy and cost  Digitize scanned maps (subdivision plats)  Use orthophotos for heads up digitizing  Include COGO descriptions: not feasible  Integrate survey data (cad): not available

March 14, 2007 Comparison of Methods Vectorized Maps Digitized Orthophotos Cogo Measurement- Based system Accuracylowestbettergoodhighest costlowest Moderately higher Much higher higher Maintenance Cost highest Moderately lower lowerlowest Vertical Integration poorSlightly highergoodbest Benefits Fast way to get started Detects conflicts Integrates gis and legal descriptions Source: Designing Geodatabases: Case Studies in GIS Data Modeling, d. arctur and M. zeiler, ESRI, 2004

March 14, 2007 Parcels Database Parcels Database  Development Process Phase 1 Phase 2 Phase 3 Collect data and line work Collect data and line work Convert to Polygons Convert to Polygons Add Attribute Data Add Attribute Data

March 14, 2007 Method Selected Method Selected  Combined method  Vectorized Maps: Edit existent Data  Digitize scanned maps (subdivision plats)  Digitized orthophotos

March 14, 2007 Base Data Base Data  Indiana Orthophotography Project  Existent Parcel Layer (Line Work)  New Subdivision Plats  Zoning Ordinances  Knowledge provided by local authorities

March 14, 2007 Edited existing Line Work  Moving Blocks

March 14, 2007 Process Process Collect Data Scan Geo- reference Edit & Digitize Verify Cycle Incorporate Hard - Copy Maps

March 14, 2007 Geo-Referencing Geo-Referencing  Locate your data in real world coordinates

March 14, 2007 Geo-Referencing Geo-Referencing  All layers must be aligned (Use Control points)

March 14, 2007 Potential Errors Potential Errors  Accuracy of original field measurements  Scale of source map  Accuracy of original drafting  Digitizing accuracy  Conflict between different records

March 14, 2007 Process Process Better Accuracy CONSISTENT WITH SCALE USE ROW FROM STREETCENTERLINES USE SNAPPING TOOL

March 14, 2007 Snapping Snapping  Improves accuracy on vertices and edges junctions

March 14, 2007 Experience Experience  City has GIS starting point  Without knowing Building Parcel Database  Trial and error process  Plan Commission Meetings: Feedback  Also located billboards and cell towers

March 14, 2007 Final Results Final Results

March 14, 2007 Thank you!! Thank you!!