Of course, the crater is bowl-shaped, not flat, so you would want to get some extra foil. The area of the crater is about 1,080,000 square meters, or 1.08 square kilometers. It's small in these images, but stands out because of its round shape and the bright rocks exposed around the rim. Zoom and scroll around the image and look for Meteor Crater.Confirm that the dimensions of the image (width, height, and bit depth) match what you read in the metadata. Using any method you're comfortable with, open the Band 1 (B10) image in ImageJ.You don't always need to read through the metadata before opening an image, but it's useful to know it's there and what information it can tell you. Metadata files are important and useful, but they're not much fun to look at. A quick scan of this file shows that all of the pixels in the images are within about 6 meters of their true positions on the ground. The last text file is the GCP (ground control points) file, which describes how close the points in the image are to the corresponding points on the ground.The image is projected in UTM (Universal Transverse Mercator), Zone 12. Click the four direction arrows to choose adjacent scenes, and click the Prev Scene and Next Scene buttons and note the dates of the scenes.
The Scene Information field tells the scene ID, the percentage of cloud cover (ideally 0% if you can find one), and the date. GloVis allows you to preview the desired scene (and the eight surrounding scenes, in case you're off a little) by entering either its WRS path and row number or the latitude and longitude coordinates of the feature you're interested in. Landsat scenes are located by their path and row numbers, and are further identified by the date. This path and row coordinate system is called the Landsat Worldwide Reference System (WRS). For convenience, each path is divided into 248 smaller chunks called rows, each row corresponding to about 24 seconds of satellite time. The satellite images continuously along this path. Each orbit follows a roughly north-south path as Earth spins underneath the satellite. Landsat orbits are fascinating (you can read more about them here), but the key thing to remember is that the satellites' orbital tracks allow them to image the entire planet between 82 degrees north and south latitude every 16 days. One advantage of this site is that it provides data for all of the spectral bands produced by the satellite. The Global Visualization Viewer is a tool for previewing, selecting, and ordering data from a variety of USGS satellite image collections. You can close the login window, but don't log out until you are finished downloading data.ĭownload Landsat Data Using the USGS Global Visualization Viewer (GloVis) After registering, log in with your username and password.
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If not, complete the registration process before continuing.
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To download data files from certain USGS sites, you need to register for a free account. Fortunately, the USGS provides free tools and services to access minimally-processsed satellite data for research. Unfortunately, these images are of limited use for scientific research. Typically, the images you find on the Internet have been heavily processed to create pretty, press release quality images. Much of this data comes from Earth-orbiting satellites such as Landsat, Terra, and Aqua.
The USGS is responsible for managing and disseminating data to other government agencies, the research community, and the public.
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The United States Geological Survey (USGS) is a goldmine for free geospatial science data.
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