1. Extension Research Presentation for
Week 2 of Saint Mary U’s
Advanced Spatial Modeling
______________________________
Kevin Byrne
September 14, 2009

2. Goal
To provide an overview of a chosen extension by
a demo/discussion using a mix of resources.

3. Background
• Title is An ArcGIS Extension for Generating
and Updating Ordinary and Multiplicatively
Weighted Voronoi Diagrams for Points, Lines,
and Polygons and author is Pinliang Dong
• Uses ArcObjects written in Visual Basic
• It is raster-based and was posted to ESRI’s
website on April 4, 2009. ESRI’s download
record shows 1410 so far.

4. Background (cont’d)
• Voronoi diagrams are tessellations that
define regions “such that each contains all
locations closer to the generating object than
to any other object in the pattern.”
• Fall under a large umbrella known as
exploratory spatial data analysis (ESDA).
• A first – and dramatic – usage was by Dr.
John Snow in order to map cholera outbreaks
in London in the mid 19th c.

8. Background (cont’d)
Dong’s extension has the following features:
• Works for point, line, and polygon features;
• Generates both ordinary and multiplicatively
weighted Voronoi diagrams in vector format;
• Assigns non-spatial attributes of input
features to cells through spatial joining; and…
• Produces ordinary or weighted Euclidean
distance raster datasets for modeling apps.

9. My Methodology-Steps
1. I searched ESRI’ site with the key word voronoi and found one script. The
extension to which it linked was downloaded from the site; its size was 3832 k.
2. It needed to be unzipped and installed with a setup.exe routine. I then turned it
on as an extension in ArcMap and docked it.
3. The install folder included a) sample data assets, and b) an html tutorial doc.
that I used to acquaint myself with its capabilities.
4. I completed the first of three phases of Mr. Dong’s tutorial using his data
5. The final (third) phase of the tutorial was the most interesting; it demanded a
deep dive into an attribute table of Dong’s .mxd file in order to explore a target
attribute column of one’ choosing. I tried this out as it is a centerpiece to the
extension’s strength; results were successful.
6. I saved the completed tutorial’s .mxd file, did screen snaps throughout the
procedure, turned on appropriate layers, and exported one Voronoi map to PDF.
7. Lastly I assembled screen snaps, final map, and descriptive textmatter into this
final report.

15. Discoveries
• Download and installation was seamless.
• Tutorial was essential.
• I hope to try this with my own data but I need
more theoretic background.
• Its blend of vector and raster output permitted
me to explore overlapping two layers with
varied transparency. These hybrid displays
were visually engaging and informative.

18. Voronoi Map With Owner-Occupied Count
3927
3863
9666
5171
10607 10607
3863
6871
8016
7007
8016
7550
Data Source: P. Dong
Extension Research, Analysis and Design: K. Byrne
Date: September 14, 2009
Course: Advanced Modeling, Saint Mary's U.

20. References
• Dong, P., 2008. Generating and updating
multiplicatively weighted Voronoi diagrams for
point, line and polygon features in GIS…
• Johnson, S., 2006. The Ghost Map: The
Story of London's Most Terrifying Epidemic…
• O’Sullivan, D. and D. Unwin, 2003.
Geographic Information Analysis…