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The 5 Layers of GIS Mapping: What They Are and How They Work

June 14, 2019  //  BY Team DataTree


If you’ve ever looked up an address on Google Maps or a real estate software program, you’ve used a form of geographic information system, or GIS. A geographic information system is an application for collecting, organizing, storing, analyzing and distributing spatial data about geographical locations and features.

If you’re a real estate professional, using a GIS system can streamline many common tasks related to geographic data. For instance, a realtor showing a client the kind of school and shopping opportunities in a neighborhood can instantly call up a map with the relevant information by using GIS technology. Here’s a look at the underlying technology that makes this type of application possible.

1. Mapping Reality: Spatial Reference Frameworks

GIS systems consist of five layers, each performing a distinct – but related – function. The most fundamental layer involves creating spatial reference frameworks. This layer takes actual physical locations and objects and represents them using a coordinate system, known as a spatial reference system (SRS) or coordinate reference system (CRS). In a spatial reference framework, the three spatial dimensions of length, width and height are typically represented by X, Y, and Z coordinates. An additional M coordinate is used to represent additional information, which can include mileage between locations or other variables such as time or temperature. For example, a surveyor might want to use a custom coordinate to represent elevation.

2. Storing Mapped Data: Spatial Data Models

The second layer of a GIS system transforms spatial reference coordinates into a spatial data model. Two different types of geographical information can be represented through spatial data models. Discrete information about objects with definite locations (e.g. roads) is stored using vector data, which is the same type of data used to create images with sharp edges such as logos. For instance, the results of a DataTree Map Search might display an icon representing a specific property on a map. Continuous information about local areas, such as maps of surface features in a certain area, are stored using raster data, which is the type of data used for images constructed from pixels, including most web graphics and photos. On the same DataTree Map Search result, the icon representing the property might appear on a bird’s-eye view overhead map showing an image of several properties in a neighborhood.

3. Collecting Geographic Data: Spatial Data Acquisition Systems

Spatial reference frameworks and data models provide a framework for representing geographic data. The next layer of GIS, spatial data acquisition systems, deals with collecting data to plug into this framework. Spatial data can be collected from a wide variety of sources, ranging from conventional methods such as surveying to high-tech methods such as satellite photography. This data can also be combined with relevant property data from many sources.

4. Turning Geographic Data into Useful Information: Spatial Data Analysis

Spatial data analysis puts the collected data to use by querying it for relevant answers to practical questions. Basic spatial data analysis provides information such as the size of a property lot or the distance between two properties. More advanced analysis can provide specialized information, such as the distance between a property and the nearest bus line, parcel boundary data or vacant property flags. DataTree’s Advanced Search function can analyze data using 60 different filters, grouped into categories such as location information, property characteristics and transaction information about sales and financing.

5. Consuming Geographic Data: Geo-visualization and Information Delivery

The final level of GIS, geo-visualization and information delivery, packages information from previous levels into a form that can be consumed by human users and delivered digitally. For instance, this can involve scaling a map to show an area relevant to a query. In DataTree’s Map Search, you can see a list of properties and scroll to the one you want to view, and the relevant map will display on the screen.

The five layers of GIS systems together collect, organize and store spatial data in a form that real estate professionals can query for useful information and display for easy viewing by themselves or clients. DataTree’s suite of services integrates GIS spatial data with property data for a powerful combination that vastly enhances your search capability while simplifying the process of searching for information, as well as making it easy to view information through interactive maps. Sign up for a free trial to find out how DataTree services can work for you.

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