### Answers

4-1: The parts of a city dedicated to office and government buildings, industrial areas, and transportation infrastructure generally are a bluish to blackish in a false color composite, owing to the dominance of asphalt and concrete and customarily to a sparsity of vegetation (mainly trees). The suburbs tend to be residential with some shopping centers, etc or industrial parks. These show as spotty or blotchy patterns of red mixed with blue, sometimes with well-defined main streets and hints of street patterns associated with homes. While it is not always the case, many suburban outer limits grade into farms and/or forests. BACK

.

4-2: Again, a subjective situation. One observation: there are few other metropolitan locales on Earth that have as large an area as seen around Los Angeles. It is truly a sprawling metropolis. BACK

4-3: The Santa Monica Mountains are in the left upper third of the image and Long Beach is near bottom center. It is a major seaport, as evidenced by the white patterns jutting into the ocean. On the map you probably observed that there seem to be more major roads than show up in the radar image. In general, roads will be dark in radar imagery because, being smooth, they scatter most of the radar beam away from the radar instrument, so that with little return signal, they appear blackish. (Of course, if they are choked with traffic, the autos act as reflectors so that a stronger return can result.). BACK

4-4: Two changes are conspicuous at the Naval Air Station: first, the six elongate white buildings; second a rectangular black feature that is probably a very large pool of water. Within the grayish area above the feature there may be two new large buildings. Across the strait of water north of the Station is the U.S. Marines Recruit Depot (west of San Diego International Airport), with apparently some new buildings. BACK

4-5: Tucson was built on a series of alluvial fans consisting of debris washed into the valley from the Santa Catalina and other nearby mountains. In its natural state, this appears as tan to light brown rocky soil with desert vegetation; in this false color image, the light yellow-brown is the color signature of this alluvial surface. Although many homes in Tucson have lawns, much of the city still retains some of this surface - hence the brownish tones. BACK

4-6: Most are easy to find. The Keys (a rewording of the Spanish "cayo" for a small island or reef) are near the bottom of the image, with Key West on the western (leftmost) tip, just at the image bottom. BACK

4-7: These are easy to pin down using a Miami map. Hollywood (a Florida town) is just at the top, with Fort Lauderdale next up, but off this image. BACK

4-8: Easy to do. Just use the bends in the river as fixing points. BACK

4-9: Again, subjective action on your part. BACK

4-10: Any good "Sherlock" could deduce this. Look at the Washington Monument (555 ft high). Its shadow is obvious. The Monument acts much like a huge sundial. The shadow's direction is about at 1:00 P.M. But, since the date of this Kosmos image is not available (to the writer), it's hard to say whether it was acquired in summer or winter but from the seeming presence of foliage on trees, the date must be sometime between April and October. If so, Daylight Savings Time applies, and the time shifts to 2:00 P.M. EDT. The monument not in the picture, but of great fame, is the Lincoln Memorial (to the west [left]). BACK

4-11:The SPOT image extends into much of the lower left quadrant of the ASTER scene. The large loop of the Seine is distinctive and should help you to locate the SPOT coverage. BACK

4-12: I think so. I believe that the Seine in the photo is the east (right) limb of the meander that courses through the SPOT scene. The bridges fit and the circular feature in the SPOT image may be the large apartment (?) building in the foreground. But, if I had had any notion that the picture I took in 1968 would be used in this Tutorial, I would have turned more to the west. BACK

4-13: This proved initially quite a puzzlement. The Quickbird image supplied over the Internet proved to be reversed relative to the SPOT image, appearing such that top would be towards the south. Here it is reversed so that, as is the usual convention, north is now on the top.

The rotation causes the Arc de Triomphe itself to seemingly lean the "wrong way". But once this was done, then the wide street called the Avenue de la Grande Armee (Napoleon's finest) was on the left in both images. The SPOT image has been rotated roughly 90° clockwise relative to the Quickbird image. Two checks seem to confirm this: 1) a cluster of 6 large buildings on the immediate circle now are on the same side, and 2)a small street that crosses Avenue Hochs to Rue Washington seems to be properly positioned as a reference; it shows up as a short black line in the Quickbird image. BACK

4-14: The reason for this is not clear as most metropolitan areas tend to have lighter tones owing to building corner reflections and other factors (parts of the city here display this characteristic). A hallmark of Florence - and many of the dwellings in Tuscany - is the red tile roofing evident in the ground photo. Perhaps the properties of the tile give rise to efficient specular dispersion (minimal backscatter) of the radar signal. BACK