Remote Sensing Tutorial Overview Answers

ANSWERS

` <>`__O-1: There is a formal definition given near the beginning of the Introduction Section. But try this for the moment: Remote sensing involves the use of instruments or sensors to “capture” the spectral and spatial relations of objects and materials observable at a distance - typically from above them. An aerial photograph is a common example of a remotely sensed (by camera and film) product. There are probably hundreds of applications - these are typical: 1) determining the status of a growing crop; 2) defining urban patterns; 3) delineating the extent of flooding; 4) recognizing rock types; 5) pinpointing areas of deforestation. `BACK <overview.html#O-1>`__

` <>`__O-2: The higher one goes, the more of the surface comes into view (i.e., area of coverage increases) but the size of the features that can be detected and separated (resolution) decreases. `BACK <overview.html#O-2>`__

` <>`__O-3: The camera was programmed to start snapping pictures at a certain time after pigeon release and continued to take more pictures automatically. But there was very little control over where the pigeon would fly or even whether the pigeon would be positioned to have the camera looking down. Most photos tended to be oblique (looking at an angle). `BACK <overview.html#O-3>`__

` <>`__O-4: During the Weather segment of local or network news. The moving cloud patterns, for example, are observables relayed to Earth from (usually geostationary) satellites orbiting 23000 miles above Earth); water vapor images also are common. The radar images of the region are usually obtained from ground radar stations. `BACK <overview.html#O-4>`__

` <>`__O-5: Of course, you as an individual may have seen a Landsat image any number of places - they now appear in a variety of practical uses (e.g., the book I have on the History of Ireland uses a cluster (mosaic) of Landsat images to picture the island on its front cover). But, a good place to look now and then is in certain TV ads or programs or in magazine ads (the classic example I’ve seen on TV shows the same subscene of the San Francisco Bay area as on the Coverpage of this Tutorial, but with the picture turned sideways [north on right side] which confirms my suspicions about the limitations of people at ad agencies). `BACK <overview.html#O-5>`__

` <>`__O-6: The fitting is subjective but as additional fix points, Ogden is near the top of the image and Provo is just to the upper right of the smaller Utah Lake. Deserts appear whitish; areas of cropland are a patchwork red and buff; the Wasatch mountains on the right side are rendered red because they are heavily vegetated with pines, aspen, etc. (red is the hallmark of vegetation in the so-called false color Landsat images. Kennecott Mining Company’s famout open pit mine, referred to as the Bingham Canyon mine is a bluish-white patch in the mountain range just west of Salt Lake City. This Landsat-1 image was taken in 1972. Since then, the Great Salt Lake’s surface elevation has been raised by several feet dry up) several feet. In my 1998 Rand-McNally atlas, the shoreline has changed shape notably, so that two islands now appear as water rises to a higher surface, and the large peninsula extending into the lake from the southeast has become once again Antelope Island. The Salt Lake City environs extend well beyond the central downtown area,which appears a dark bluish representing light reflected from buildings and streets - this central area has few trees, hence little vegetation to contribute their signature reds to this false color composite. Downtown as seen in the oblique aerial photo to contain many tall buildings. Look at the photo - you will notice that the residential areas have an abundance of trees, so many that, in the summer Landsat scene, their foliage shows up as the characteristic red signature of vegetation. `BACK <overview.html#O-6>`__