What is GIS? #
GIS stands for Geographic Information System. These systems are incredibly powerful; they allow you to store, manage, analyze, edit, visualize, compare and correlate different sets of data.
You are likely interacting with a form of GIS everyday! Google Maps, for example, is probably the most common for people. It has a base layer that includes street names and highways, then multiple different layers on top of that base layer that shows restaurants, businesses, house numbers and much more! Weather apps that utilize maps to show you radar, cold fronts, storm paths, and air quality are also using a form of GIS. If you use websites like Realtor.com or Zillow, they are using GIS to show you a visual database of homes and apartments in your area.
Outside of consumer use, GIS is utilized heavily in the business world. For example, your city likely utilizes a GIS system to track their roadways; tracking things like their age, condition, material and traffic density. Insurance companies will often utilize GIS systems to adjust your rates; Stacking data layers that show property crime, flood plains, and parcel information. New business owners will also often use GIS to determine the best place for their new liquor store; tracking existing liquor stores, nearby schools, and available commercial property to find an optimal space.
Elements of a GIS map #
Datasets #
Datasets are maps on their own, however, can be imported into a map to be used as layers. In government-use cases, they will typically have a dataset for each object type they are tracking but that isn’t always the case. Most municipalities will have a dataset containing their stormwater pipes, another dataset for their manhole lids, another dataset for interceptor junctions and so on. So ideally, when building a map in a GIS sense you would build a dataset for each location type: your mines, your drains, your bandos, but GIS allows a lot of avenues for your organization.
When imported into a map, you can treat a dataset just as you would a layer; adjusting transparency, visibility, styling, ect.
Features #
Features are your map pins, lines, and shapes. Each feature in a given dataset represents an object. There are three basic types of geometry you will encounter in GIS datasets:
Points
Points are your pins. Just a single point with coordinates on a map. On public maps, a GIS might utilize points to represent fire hydrant locations, street lights, or manholes.
Lines
Lines are segments that go from a Point A to a Point B. On public maps, these often represent pipes, roads, or directions.
Polygons
Polygons are your shapes; your circles, triangles, squares and all of that. On public maps, these often represent property boundaries, floodplains, building shapes, amongst other things.
Attributes #
Each feature in a dataset can have an endless list of what are called Attributes. Each line segment in a stormwater pipe map will often have its own set of attributes, such as an ID number, condition, length, height, material information, and more. These are organized into a spreadsheet of sorts; which allows you to filter based on the attribute fields you set up.
In your own maps, you might utilize attributes to keep your exploring map contained to a single dataset rather than having separate ones for mines, sewers, bandos, roofs and other things. In addition to having a column in your attribute table for “Name” and “Description”, you can also add a “Type” field in your attribute table and have a list of inputs to choose from. But its really up to you how you want to organize your maps.
Some maps you’ll come across might have extensively filled out attributes, and some might be very sparse; it just depends on who created the dataset.
