Using CAD Parcel data with the Local Government Solution July 25, 2012 Using CAD Parcel data with the Local Government Solution Chris Buscaglia & Amir Bar-Maor

CAD Parcel Data Characteristics Computer Assisted DRAFTING File based and static Usually not spatially referenced Attribution as floating text (annotation) Line based  overshoots & undershoots Contains unnecessary geometries (map elements) Layer structure is not consistent Does not contain Tax Parcels Designed for drafting

Ground to Grid Correction Ground: the measurements as they are captured by the surveyor on the ground. The direction might be relative to several definitions of north. Grid: a projected coordinate system on the ellipsoid. E.g.: State plane Ground to Grid Correction: scale & rotation

CAD Integration Methods Method 1: The Ad Hoc Method Method 2: The Systematic Method

The Ad Hoc Method Ad hoc steps Add CAD Data Select Lines Copy & Paste Clean & Build Join Attribute Parcels Ground to Grid

The Ad Hoc Method With small datasets (less than 1,000 lines) because: When should I use it? With small datasets (less than 1,000 lines) because: Hard to fix errors on a large dataset Hard to join a large dataset Not limited to CAD lines Attention: Measurements are calculated during construction (ground)  do not georeferenced the CAD file if it is in ground

Ad Hoc Method Chris Buscaglia DEMO

The Ad Hoc Method Easy Fast Good for a small dataset (few parcels) Pros Easy Fast Good for a small dataset (few parcels) Ability to manually correct the COGO dimensions for each line

The Ad Hoc Method Limited to a few parcels (1,000 lines) Cons Limited to a few parcels (1,000 lines) Might be time consuming to fix many line errors Line category has to be set manually Need to set parcel type and name manually … It might be just as fast to re-COGO

The Systematic Method Systematic Method Steps for a subdivision Copy Lines to Staging GDB add COGO Attributes Filter Out Unnecessary lines Use Topology to Clean Lines Calculate COGO Prepare Line Attributes Separate Lines by Parcel Type Import Parcel Names as Annotation Create Polygons Attribute Polygons Create Topology & Import Subdivision As Unjoined Join Subdivision Import & Join Lot Parcels

The Systematic Method Large datasets Why use this method Large datasets QA and analyze the data in a staging environment Preserves COGO-ed dimension Efficient attribution for parcel names Ability to improve geometry using geoprocessing tools and Add-ins (e.g. curves) Similar to a migration process Can be streamlined using a geoprocessing model

Systematic Method Chris Buscaglia DEMO

The Systematic Method Captures parcel attributes Pros Captures parcel attributes Can be automated and streamlined Scalable—Can process thousands of parcels at a time

The Systematic Method Involves more steps Cons Involves more steps Not cost effective for only a few parcels

Methods Comparison Parameter/Method Ad Hoc Systematic Size: Few parcels Recommended Too much effort unless automated Size: Many parcels Limited Good COGO attributes Preserved Automation Not possible Possible when data is structured Parcel attributes Have to be entered manually Can be obtained from annotation Digital submission standard does exist

Why Maintain Your Measurements (COGO)? Ability to use labels or feature linked annotation. Eliminate the need to go to the clerk's office to get legal dimensions QA the data you receive: misclosures, rotation… Maintain accuracy and run a meaningful least squares analysis (LSA). Stated Area is calculated from COGO. Misclosure is stored and based on COGO. Categorize your lines correctly: boundary, road frontage…

Best Practices Use a digital submission standard Update the pasted geometry with the record values

Road Ahead: 10.1 SP1 Automated workflows for maintaining Parcels

10.1 SP Automated Workflows Parcel Workflows 10.1 SP1 – even easier, more streamlined LGIM enabled Parcel Fabric available with the core ArcGIS system Workflows available with the core ArcGIS system, upgrade available at 10.1 SP1

Road Ahead 10.1 SP1 Amir Bar-Maor DEMO

UC Presentations Technical Workshops Sessions to attend Technical Workshops Editing Parcels with the Local Government Information Model Thursday, 8:30 - 9:45 Demo Theaters Creating a Tax Map using the Local Government Solution Thursday, 11:00 – 11:30

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