![]() X-rays, ultraviolet rays, visible light, infrared light, heat, microwaves, and radio and television waves are all examples of electromagnetic energy.Ī portion of the electromagnetic spectrum, ranging from wavelengths of 0.1 micrometer (a micrometer is one millionth of a meter) to one meter, within which most remote sensing systems operate. Electromagnetic radiation is a form of energy emitted by all matter above absolute zero temperature (0 Kelvin or -273° Celsius). Most remote sensing instruments measure the same thing: electromagnetic radiation. You will see that digital remote sensing is a little like scanning a paper document with a desktop scanner, only a lot more complicated. The appeal of multispectral remote sensing is that objects that are indistinguishable at one energy wavelength may be easy to tell apart at other wavelengths. ![]() Many of the objects that make up the Earth’s surface reflect and emit electromagnetic energy in unique ways. Here we consider the nature of the phenomenon that many, though not all, remote sensing systems measure: electromagnetic energy. Nature of Remotely Sensed Image Dataĭata, as you know, consist of measurements. Add comments and questions of your own, if any.Ĭomments and questions may be posted on any page of the text, or in a Chapter-specific discussion forum in ANGEL.Ĩ.3. Read comments and questionsposted by fellow students. See the Calendar tab in ANGEL for due dates. Instructions are provided for each activity.ĪNGEL > Lessons tab > Chapter 8 folder > Chapter 8 Graded Quiz. Perform a simulated unsupervised classification of raster image data.Find, preview and acquire Landsat data at the USGS EarthExplorer site.View the global distribution of Landsat scenes at USGS’ Spacetracks site.Study remote sensing fundamentals and case studies at USGS’ Earthshots site.Go to ANGEL > Lessons tab > Chapter 8 folder > Practice quizzes are not graded and may be submitted more than once. You can also navigate the text via the links in the GEOG 482 menu on the left. Click on the links at the bottom of the page to continue or to return to the previous page, or to go to the top of the chapter. Chapter 8 Checklist (for registered students only) Step You may find it useful to print this page out first so that you can follow along with the directions. The following checklist is for Penn State students who are registered for classes in which this text, and associated quizzes and projects in the ANGEL course management system, have been assigned. Note: the first few words of each comment become its “title” in the thread. In addition, you will be able to reply to other posts at any time. Once your comment is posted, you will be able to edit or delete it as needed. When you are finished typing, click on either the “Preview” or “Save” button (Save will actually submit your comment). To post a comment, scroll down to the text box under “Post new comment” and begin typing in the text box, or you can choose to reply to an existing thread. ![]() In addition, there are discussion forums available in the ANGEL course management system for comments and questions about topics that you may not wish to share with the whole world. Particularly welcome are anecdotes that relate the chapter text to your personal or professional experience. ![]() Registered students are welcome to post comments, questions, and replies to questions about the text.
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