GIS Application in Real Estate (Austin Area Study)

Austin is among one of the fastest growing cities in the nation. With the tremendous population growth, housing has been in very high demands for the past few years. With the powerful ability of GIS in combining data and showing it on the map, the project will try to develop a database system using GIS to assist in the real estate market in Austin area. The database system can assist realtors to locate a house for the customers and also can assist real estate developers to determine the best locations for housing development.

A fundamental activity of regional planning program is the development of long-range forecasts of activity¹. GIS techniques are very useful tools for regional planning in determining future growth of a metropolitan area like Austin. GIS has the ability to aggregate existing data and can overlay one type of data over another. And the most powerful contribution is that GIS can be used to display data for both presentation and analysis as well.

Weekends are busiest days of the week for realtors because that's the time when most people are available to search houses. However, a good deal of time is spent on traveling and the customers spend a lot of time looking around. With a GIS based information system, much of the information can be displayed on map and the customers can do the pre-selection at realtors' offices instead of driving around to see houses. After the pre-selection process, realtors and customers can narrow down potential candidates and make trip to only those chosen sites. Further more, if everything can be put on the web, realtors can let the customers do the pre-screening themselves and contact the realtors after they have chosen some sites they are interested in. GIS application in this area not only can save time but also costs as well.

Another area of real estate is housing development. Developers are looking for potential empty sites to develop residential houses. However, it is not an easy to find a suitable site location. As the three most important aspect in real estate business: "location, location, and location", developer can be too careful in choosing locations for future development. With the assistant of GIS technology, developers can combine information, perform analysis, display results in one database. It would be a useful tool for selecting potential site developments. Some of the factors involved in site selection are land cost, land usage, accessibility, neighborhood, school district, traffic to downtown, utility availability, and future neighborhood development, etc.

In summary, the project will contain two applications, one for realtors and the other for real estate developers.

There are two types of data involved in this project: GIS data and text data and they are explained in details in the following section.

First, Austin area jurisdiction shapefile is used to define the geographical scope of this project. Associate with the jurisdiction, Austin area lake shapefile, road shapefile and school district shape file are obtained from exercise 3 and Texas Natural Resource Information System. Next Texas land cover dataset was obtained from USGS National Land Cover Dataset. The downloaded file was a big 400 MB imagine file. In order to further use the image file in Arc/View 3, the Texas Land Cover Dataset image file was converted into raster data (grid file). In the grid file, we can display the different land cover classification in Arc/View 3. Figure 1 shows the raw image data for SE Texas Land Cover Dataset and Figure 2 shows the gird file for SE Texas Land Cover Dataset (Austin area in black).

GIS Data:
Data Type	Data Name	Source
Vector Data	Austin Jurisdiction	Exercise 3
	Austin Lake	Exercise 3
	Austin Road	Exercise 3
	Austin School District	TNRIS

Image Data	Texas Land Cover Dataset	NLCD

Raster Data	Austin NLCD Grid	Convert from Image File

The second type of data collected is real estate information from websites. The information includes housing prices, land costs, housing locations and so on.

The first step in data preparation if to display all the information in one map. The shape files are in two coordinate systems (NAD 27 and NAD 83). I converted all the shapefiles into NAD 83 using Arc/View 3 Map Projection Wizard and the projection parameters are summarized as follows:

Projection:	Albers Conical Equal Area
Datum:	NAD83
Spheroid:	GRS80
Standard Parallels:	29.5 degrees North Latitude 45.5 degrees North Latitude
Central Meridian:	96 degrees West Longitude
Origin of the Projection:	23 degrees North Latitude
False Easting:	0 meters
False Northing:	0 meters

The image data from NLCD is in ASCII format and in order for Arc/View 3 to read it, a header file has to be created. The directions for header file creation can be found in USGS. The header file I created can be summarized as follows:

BYTEORDER:	I
LAYOUT	BIL
NROWS	24577
NCOLS	20078
NBANDS	1
NBITS	8
SKIPBYTES	0
ULXMAP	-364860
ULYMAP	1047900
XDIM	30
YDIM	30

By using the Spatial Analyst in Arc/View 3, I successfully convert the image file into grid file (refer to Fig.2 above). However, the grid file contains the whole SE Texas and is 270 MB in size. The part I need is only the land cover data for Austin area. One of Dr. Maidment's graduate student Brad Hudgens, he did a project Wrap117.apr (which can be found in his web page) that can clip grid to polygon. With the help of Wrap117.apr, I clip the land cover data to Austin jurisdiction shapefile. Figure 3 shows the land cover dataset for Austin are only.

By converting the Austin area land cover data into shapefile, we can add field and add data we need into the dataset. This part was done by opening the database file in excel and input the data in excel. Then load up the updated data in Arc/View 3 and thus we can display our information in map. The data added includes land price, school district evaluation and land usage evaluation. Because the huge amount of points involved in Austin metro area, only Austin Independent School District is used in this data processing. By giving weights to different fields, the excel can calculate a final index score for our development site reference.

Scenario: A customer is looking for a house at Austin area and some of his criteria are:

By looking at the GIS information system for Austin area with all the information (road access, water body, school district, house availability, etc.) shown on the map, the realtor can quickly pick up some potential points of interest for that customer. Fig.4 shows one area that satisfies these particular needs.

After selecting the potential area of interest, the realtor can zoom in and take a detail look at that area to see if it fulfills the customer's needs. Also, more information such as house availability, house pictures, house locations and so on can be examined using Arc/View 3. Figure 5 shows the close up for the chosen area in Fig.4 and some basic information of the house available for sale. More detail information about this house can be found in this link (9.5 M house, worth a look).

By exploring the housing information in the GIS system before actually go out to look at the houses, both realtors and customers can benefit from it. This is not only a great tool for realtors but also for customers as well.

The information combined in GIS database system is an useful decision support tool for developers. On the map, the developer can check land cover and land use, residential housing intensities and further on to determine the trend of housing development. With the kelp of the database, the developer can input his own criteria for determining potential development sites. Figure 6 illustrates the potential areas (in light color) that are suitable for future housing development based on certain pre-set criteria. By taking this information as a reference for future project development, the developers can have better understanding of the areas and can have a bigger picture of the area. Also, values can be modified or changed based on updated information or different evaluation criteria. This GIS database system can provide most up-to-date information and serve as a basis for decision making process.

GIS is a very powerful in aggregating data and presenting data, especially its ability to present data in map (image) format. Image format is the most efficient way of presenting information that mankind can understand. GIS not only possesses the power in presenting data in very efficient way, but also the ability to process data (vector, raster, TINS and image data).

GIS has a great potential in real estate applications. The project only explores two simple but useful applications of GIS in real estate, one is for realtors and the other is for developers. In these two applications, GIS is proved to be informative, useful and "colorful". This project just serves as the beginning of the GIS application in real estate and it turns out to be a very good beginning. It shows that more efforts can be put into the development of GIS in real estate and the benefits are foreseeable. In short, not only did I find GIS has great potential in real estate but I also found myself having fun doing the project and I did learn a lot of things from this project.

Said Easa and Yupo Chan. "Urban Planning and Development Application of GIS", ASCE, 1999