GEOG 488
Acquiring and Integrating Geospatial Data

Assessing Sources for Remotely Sensed Data


A. Download the Lesson Data

My story:

Centre County has digital orthophotos that are available to the public, but they are becoming dated. I would like to investigate new sources of high resolution satellite imagery to see if these might be a good update for my current geodatabase of the county. I was interested in determining if current data has already been acquired for the county, it's type, format, and cost per square mile. I was also curious about remotely sensed data that could be acquired freely from the Web for my county.

I acquired aerial photography from the county, aerial photography from PASDA, and free satellite data (ETM+,GeoTIFFs) from the Global Land Cover Facility (GLCF) site. If you want to see these various products unzip lesson4files and open lesson4.mxd. As you can imagine, these data are large. I eliminated quite a few images that I wanted to show, but the .zip file is still about 344 mb. I included the images of Beaver Stadium (Penn State's football stadium) because it is a large feature that stands out. It's interesting to compare the different products. I also looked at the sources provided below to get information about acquiring high resolution satellite imagery.

Registered Students download from ANGEL the Lesson 4 data ( to a new folder (e.g., C:\MGIS\GEOG488\Lesson4).

I want to thank Doug Miller for his contributions to this lesson.

Doug's story:

In the introduction, you read about a scenario that Doug Miller is interested in. Doug teaches a remote sensing course in the Geography Department on campus and will probably be developing an online remote sensing course for the MGIS Program. The example was given to get you thinking about some scenarios in which remotely sensed data are used. I will be deferring to Doug for some of your more in-depth questions about remote sensing.

B. Get a Refresher on Remotely Sensed Data

Remote sensing is the art and science of acquiring information about an object without being in physical contact with the object. Remotely sensed imagery can be collected at scales ranging from hand-held devices to orbiting satellites. Remote sensors rely on the interaction of energy with the area of interest. Sensors mounted on aircraft or satellite can collect imagery in multiple portions of the spectrum for use in feature identification. A comprehensive discussion of remote sensing is beyond the bounds of this exercise. However, in the "Resources" section you'll find a list of several very good texts that can be consulted for detailed information concerning the remote sensing process.

Satellite remote sensing, as applied to natural resources management, has been around since the early 1970s when NASA launched the first of a series of satellites that was to eventually become the "Landsat" program. In the intervening 30+ years, the number of earth sensing satellites has grown rapidly, with increasing spectral and spatial resolution and opportunities to combine, synergistically, information from multiple sensors. Commercial vendors now vie with the government-sponsored sensor programs for the consumer audience. For a quick, self-guided overview of several current programs and sources of remotely sensed data, explore the following:

That's it for Part I!

You have just completed Part I of this module, which involved getting a refresher on remote sensing and browsing some sites that provide remotely sensed data. In Part II, you will assess remotely sensed data in your local area.