I am a little obsessed about maps, and it’s all my Dad’s fault.  One of my earliest memories is how he turned my least favorite meals into a geography game.  He would cut my food into the shapes of different states, and would then ask me if I could eat, for example, the whole state of Connecticut.  After stuffing that piece of food into my mouth, I’d laugh hysterically at the thought of eating an entire state, forgetting that I’d just eaten the food I hated most. 

Luckily for me, this obsession has helped me professionally, since  I’ve ended up working with Geographic Information Systems (GIS).  This technology can be a powerful tool for helping people visualize large amounts of data by presenting the data as a map.  The technology can improve the quality of spatial data, and can help determine where things should be located to accomplish real-world objectives.

GIS provides ”topology rules” to ensure that the location of something makes sense in relation to other things.  A house can’t be located within an ocean.   Each salesperson for a particular company should have an exclusive sales territory.  Driveways connect to streets.  And so on.

Microsoft provides a suite of tools for enforcing topology rules using SQL Server Spatial, which has been available since SQL Server 2008.  Much to my surprise, this technology provides even more power and flexibility in defining topology rules than ESRI’s ArcSDE 9.3 product.  And using ESRI’s Data Interoperability extension, ESRI products can read and write directly from SQL Server Spatial.

Using SQL Server Spatial and its topology rules, I was able to solve a challenging problem involving the placement of vessel moorings to eliminate vessel collisions.  Vessels move around their moorings due to tides and winds, and the pattern of movement depends on factors including the length of chains and the length of the vessel, as well as whether the vessel is attached to one or two moorings. 

The first step to solve this problem was to calculate the potential swing areas for each vessel based on the current information in the database.  For the geeks out there, I did this using a user-defined function that returns a geography data type.

The second step to solve this problem was to create topology rules that identify and prevent potential collisions between vessels.  A small overlap in vessel swing areas is not a problem, because similar boats will swing in similar directions at the same time – if there are winds from the North, for example, all the vessels will typically be found at the southern end of their swing areas.   But significant overlaps in swing areas are definitely a problem.  Using SQL Server’s spatial functions, we can determine the percentage overlap between each set of swing areas, and can create a topology rule that the moorings cannot be placed if the overlap percentage is too high.  This ability to implement a topology rule based on a quantifiable measurement is very powerful.  For comparison, ESRI’s SDE topology rules allow you to prevent overlaps or require overlaps, but they don’t allow you to allow a certain degree of overlap.

Using SQL Server Spatial, you also have significant flexibility in handling data that violate your topology rules.  On the stricter end of the spectrum, you can prevent bad data from being stored in the database at all.  On the looser end of the spectrum, you can allow storage of the “bad” data and create a query that identifies topology violations.  In the middle of the spectrum, you could warn about topology violations during the update process but allow overrides. 

In summary, SQL Server Spatial has a powerful arsenal of tools to help validate and optimize the location of objects.  It is definitely worth exploring to see if it might meet your needs.

P.S.  Now that I’m a father myself, I tried cutting my daughter’s least favorite foods into the shape of various states.  It hasn’t worked at all.  She must be a lot smarter than I was at her age.

Brad Hurley

When I meet someone for the first time, and they ask me what I do for a living, I often pause before I answer. I’m usually pretty sure they are unfamiliar with what G.I.S. is or what it is used for. For clarity purposes, G.I.S. is an acronym for Geographic Information System or Science—depending on the situation. In simple terms, it is the combination of an atlas and an encyclopedia. Instead of going into a long dissertation on the ins and outs of G.I.S. and how it works, I usually ask if they use Google maps or if they have a GPS device in their car. They are the most obvious and most widely visible G.I.S. products, but there are so many things that we see and use every day that exist or occur because of G.I.S.

From the time you wake up in the morning through the long night when you are asleep, somewhere, there is a G.I.S. or a G.I.S. product at work. There is also probably someone, such as myself, creating the graphics and feeding in the data behind those graphics into a database that works in the G.I.S. As you wake up in the morning and watch TV or listen to your radio, the commercials you see and hear are products of a G.I.S. At some point in the process demographics were fed into a computer and a map was created showing the best market for a given product or service based on specific criteria that would be ideal for advertising and selling.

You get into your car to drive to work on streets that were planned out using a G.I.S. to map their placement and layout for highest efficiency and safety. Their maintenance—paving, repairing, snow plowing and sanding—are all monitored and scheduled using a G.I.S. As you pull up to the ATM, you may not realize that it was placed there based on findings from a G.I.S. business analysis. The same goes for the gas station, donut shop, and home improvement store that you pass by. The property taxes on the houses you pass, as well as the one you live in, are linked to the G.I.S. by your municipal tax assessor. The underground water pipes and manholes that you drive over are all recorded in the G.I.S. The roads and directions that show on the in-car navigation system or GPS device you may have were all created using G.I.S. software. The traffic lights on the street are cued to change based on information from a G.I.S. about travel speeds, street length, and the amount of traffic over a period of time. The cell phone you may use to tell your employer that you are running late this morning connects to a cell tower that was placed where it was based on a G.I.S. view-shed analysis.

The G.I.S. Iceberg

When you fly on a plane, the route it takes is based on a map of air traffic patterns created by a G.I.S. If you used any of the internet travel sites to book your trip, the hotel chosen by the web page to be closest to where you wanted to be was found based on G.I.S. information.  The weather map or report that you watch on the news or weather station was created or assisted from data in a G.I.S. This is all just the tip of the G.I.S. iceberg!

G.I.S. is an incredibly versatile tool. It is used in so many different professions and places. Everything from marketing and product distribution, to fire, police, and the post office. I’ve even known some people to use G.I.S. for furniture placement design and picture arrangement on a wall. The products of G.I.S. are used in things we see and use everyday in our homes and around where we live. 

The Fuss & O’Neill Technologies GIS technicians and analysts produce a wide variety of products and services for many different types of clients and projects. They range from simple maps, to analysis reports, charts, graphs, databases, virtual 3-D images, and much, much more!

By now I’m sure you have a good idea of how big a part G.I.S. plays in our every day lives. It helps us answer questions like, “where is the nearest coffee shop?” or “how many miles til the next gas station?” or “how do I get to my friend’s new house?” When you get these answers, think thank G.I.S.

Thad