Use of Conflation Softwarein US Census Bureau's TIGER

Coordinate Correction Process

Prepared for ESRI User Conference 2003

Prepared by Bernard CatalinottoGeo-Information Services, JV

Alexandria, VA

July 10, 2003

Conflation Tools in TIGER Correction Process

Overview Background What is Conflation?

What is MapMerger? Standard Approach Creative Approach Results & Next Steps

Initial and Major Programs

TIGER Coordinate Correction Initial Programs

Census R&D – 77 Counties Geo-Serv Contract – 190 Counties

Major Program MTAIP/Harris Corp – 3000+ Counties

Task 4/Geo-Serv Project

Coordinate Correction Process

1. Data Preparation (Local File)2. Coordinate Correction3. Geo-Serv QC & Final Fix4. Census QC5. Upload into TIGER DB

Task 4/Geo-Serv Contract

Coordinate Correction Tasks

Step 1 Conflate TIGER to Local file Match all matchable features

Step 2 Find and Fix Flag issues, resolve, fix, flag action

Step 3 Prepare Deliverables Re-format Prepare QC Reports

Run QC programs Perform 100% Visual Check

What is Conflation? Combine 2+ files -- create RESULTS file

includes best aspects of each file RESULTS file

Source file attributes…..”Brains from TIGER” Target file graphics…….”Beauty from Local” Differences are resolved

Rubber-sheet unmatched source features (“Orphans”)

What is MapMerger?ArcMap extension for automated conflation Automatic Match

70% to 95% of the features automatically one-to-one matched

Match editing tools for manually editing the results of

automatic matching Creates conflated data set

Conflation using MapMerger1. Node match2. Line match3. Transfer attributes Creates conflated data set

Conflation - Vendor 1 (EarthData)

Standard ApproachNode match

Match by layer 45 meters; visual check; fix errors 60 meters; visual check; fix errors

Line match Match; visual check; fix errors

MapMerger Goal 80-90% of all possible matches

MapMerger -- NODE MATCH – Automatic Results

MapMerger – LINE MATCH -- Automatic Results

MapMergerManually Edit Line Match Results

Conflation in MapMerger - Vendor 2 (Pixxures)

Creative Approach[Note: Skip Node match]1. Start with Auto Line match

1 meters; check no errors 2 meters; check no errors Stop when encounter errors -- usually around 7

meters2. Manual Line match3. QC/fix in MapMerger

Run Census/Geo-Serv/Custom QC programs Fix errors, rerun conflation in MapMerger

After MapMerger Minor QC/fix; prepare deliverables

Results & Next Steps Results

Efficient use of conflation software & ESRI GIS technologies

Next Steps All three vendors making substantial

contributions to program success Goal: Complete 190 counties by 9/30/03