JEFF

1. By looking at the small changes in the sea level, you can tell what the seafloor looks like because the differences in land mass causes differences in gravity, which pushes or pulls the water at sea level. This was called pwer series expansion.

2. Seasat would send off microwaves which would bounce off the sea level back to Seasat. By sending out many waves and mesuring the time it takes for each wave to return, Seasat could scan the entire sea leavel and make a map.

1. The dimetions of the image at 100% magnification will be 3 inches by 3 inches. There will be 144*144=20736 pixels in the image.
2. 20736(pixles)*8(bits)=165(KB)
3. 20736(pixles)/9=2304Pixles=48 pixels per inch -- image will be 9 times as large, but same size--density must be one nineth as large

JUSTIN

1.the shape of the ocean (sea surface) is determined by gravity. Changes in the gravity feild will alter the height of the sea suface. Mountains or volcanos on the ocean floor create strong gravity fields. thus causing the sea surface to rise. Vallys or rifts in create waek gravit fields, thus creating similar but smallre "vallys" on the surface. Measuirng these differences give us an accurate map of the sea floor.

2.Seasat sent thousands of pulses of microwave radar to the sea surface every second.Those pulses were timed upon returning to the satellite and the information was processed into altimeter readings. The readings were precice to about 5 centimeters and thus Seasat was able to form a toporaphic map of the surface of the ocean.

3.the image has a total of 55,24 pixels. Depending on the bit value for each color, each pixel can have as much as 16.8 million colors.

4. I don't understand how to calculate the image size.

5. The image size is proprtional to the number of pixels per inch. Therefore the total number of pixels would have to stay the same so there would be 48 pixels per inch.

MIKE

1) It is possible to "get a picture of the seafloor by measuring small change in the level of the sea suface" by seeing "gravity anomalies." Gravity's influence on the sea surface height is not what we would expect. Instead of pulling the water down, when there is a ridge, there is a bulge in the water. When there is a rift in the seafloor, there is a slight drop in the water. So these changes are plotted on a computer a map can then be seen.

2) Seasat measures small changes in the level of the sea suface by "firing off a thousand pulses of radar at the sea below, generating 25-to-30 million measurements of the ocean surface." The radar altimeter would fire one thousand radar pulses at the sea surface every second and send the signal back to the tracking system.

I had trouble with the computer graphic problems. I wasn't too sure about what they were asking or how to figure them out. This is my interpetations of them.
1)A image 3 inches by 3 inches in size, with 144 pixels/inch would have 1296 pixels. It is a color image 3 inches by 3 inches.

2)1296 pixels, don't know how many bit color

3)I'm not sure because if you compressed the file, it would depend on how many repeating numbers there are. I don't know if the the same holds true for making the image larger. If the amount of pixels stays the same, there would be 16 pixels/inch.

DAEMIAN

I Q: 'How is it . . .? ' A: The reason that small changes in the surface of the sea make a map of the seafloor possible is related to Earth's gravity field. It is not a uniform field of gravity which extends up from the seafloor. The rises and dips of underwater geography ramify variant gravitational effects, respectively, upon the surface of the oceans: as if the undulating gravitational field projects a miniturized contour model of the seafloor on the surface of the oceans. One might expect that an underwater mountain, for example, would simply have a stronger field and that a corresponding dip would occur above it on the surface of the ocean; in actual fact, the top of the mountain has a relatively weaker gravitational influence than the *sides of the mountain, which have much more mass and gravitational pull; all in all, an underwater moutain will cause a *dip above it on the surface of the sea, due to the gravitational differencial between its top and its sides (a phenomenon that Hall called 'counter-intuitive').

Q: 'How did Seasat . . .?' A: Seasat, using five sensors including a microwave altimeter twice as sensitive as that of *Geos 3, bounced radar pulses of the oceans's surfaces which reveals water levels to within 1 or 2 inches. 'Every second [in the summer of '78], Seasat fired off a thousand pulses of radar at the sea below, generating 25-to30 million measurements of the ocean surface' (Hall 79).

II Q: 'What does it . . .?' A: Without some idea of *which considerations are important in this question: the meaning of a 3"X3" image with 144 pixels/inch is that the image is a (432 pixels) X (432 pixels) square. This seems like a rather low resolution image.

Q: 'How big is . . .?' A: Without some standard for comparision in this question: the uncompressed file above is going to be quite large. Its size will depend however, upon how many bits are used to describe the colors of its pixels, wherein a higher bit scheme will mean a larger file than a lower bit scheme.

Q: 'If the file . . .?' A: Since the file's size is the same, and the image's dimensions have increased X3, the original 144 pixels/inch will be redistributed over 3X the area, and therefore there will be a third less pixels per inch, or 48 pixels/inch.

BRIAN

1. A. It's possible to get a picture of the seafloor measuring small change in the level of the sea surface because you can infer entire mountain ranges, valleys, and subtle seafloor undulations. There is a mathematical relationship between the height of the sea surface and the gravity pull of the sea surface below.

B. Seasat measured small changes in levels of the sea surface by using five-ocean monitoring sensors, including a state-of-the-art microwave altimeter. The sensitive equipment fired off a thousand pulses of radar at the sea below, generating 25-to-30 million measurements of the ocean surface.

2. A. It means that there are a total of 1296 pixels in the image.

B. The uncompressed image file with the above specifications is 547k.

C. There will be 48 pixels/inch. Assuming that the file size stays the same, and you are increasing the dimensions (and reducing the resolution) by a factor of 3, 144/3 = 48 pixels

JOSE

1. It is possible to get a picture of the seafloor by measuring small change in the level of the sea surface by using a microwave altimeter, which fired radar pulses at the sear surface then detected a variation in the sea surface.

2. Seasat's altimeter sent a radar pulse at the sea surface every second and detected varitations of 1 to 2 inches. Seasat could measure varitations with a sensitivity down to five centimeters.

3. For an image to be 3" by 3" with 144 pixels/inch would mean that its file size would equal 547k (RGB).

4. An uncompressed image with the same specifications would be 729k (CMYK).

5. In order to keep the same file size of 547k for the new dimensions of 9" by 9" then the resolution is going to change to a much lower number-48 pixels/inch.

DENNY

1. a) How is it possible to "get a picture of the seafloor by measuring small change in the level of the sea surface"? It start with an instrument known as radar altimeter that was equipped in a satellite called GEOS 3. THe altimeter measures microwaves that was bounced off the surface of the sea. The data from this measurement is in a form of electrocardiogram lines with latitude and longitude. By doing a calculation, called power series expansion, on the data, Haxby was able to create ocean floor topography. This was done by identifying the variations in the sea surface given by the data. Measuring these variations also enable us to locate valleys on the ocean and seafloor waves.

b) How did Seasat measure small changes in the level of the sea surface? The same way that GEOS 3 does it, by using microwaves altimeter. Except it was twice as sensitive for Seasat. The seasat could measure variation with a sensitivity down to 5 cm from altitude of 500 miles. It shots off thousand pulses of radar/ second, creating 20 to 30 million measurement of sea surface. Haxby however, still had to translate the data to map because Seasat failed its mission. From Seasat data, Haxby determined that gravity field is the cause of small changes in sea surface.

2. I really had trouble in finding the answer for these questions below. The notes did not really explain how to get the answer. I am going to answer it just based on my understanding...which I do not think is correct.

a) What does it mean for an image to be of 3" X 3" in size, with 144 pixel/inch? Each inch of an image can display 144 different combination of red, blue, and green phosphors brightness. So the whole 3" by 3" image can display (144 X 9) a max of 1296 different colors at one time.

b) How big is the uncompressed image file with the above specs? Since it takes 7 bits to specify a color, an uncompressed file with 1296 different colors will take 10,368 bits of memory.

C) If the file size is kept the same, but the image is now made 9" by 9" how many pixels will there be per inch? Explain? With the same memory, the whole 9" by 9" can only take the same amount of pixels as the 3" by 3" which is 1296. So the whole 9" by 9" resolution has to change to (1296 / 81) 16 pixels/inch. So the resolution of the image is lowered if memories allowed is decreased.

ROB

1. It is possible to get a picture of the seafloor by measuring the sea surface levels because of the gravitational forces that ridges and depressions create. These gravitational changes create bulges or depressions in the water levels at the surface.

2. Seasat measures the changes in the sea surface by using an altimeter that sends radar pulses 1000 times per second to the ocean surface. These radar pulses can detect a change in the surface to as little as 1 to 2 inches.

When an image is 3x3 and 144 pixels per inch, it is physically 3x3 inches and the resolution is 144 squared. In this image you would have 186624 pixels. (144 squared times 9)

The uncompressed image file above is 1306368 bits. There are 7 bits per color times 186624 pixels.

If the file is kept the same size , but the image is made to 9x9, there will be 48 pixels per inch. The overall number of pixels in the 3x3 was 186624. 186624/81 inches = 2304 pixels. Take the square of that for pixles per inch which is 48.

CASEY

1. a)It is possible to get a picture of the seafloor by measuring the gravitational pull of the sea surface; we can derive a relationship with the height of the ocean floor and the gravity at the surface. By measuring surface changes of a foot or two, we can infer mountain ranges, velleys, etc. through a "power series expansion".

b)Seasat measures small changes in the surface of the sea with a microwave altimeter that fires off 1,000 pulses of radar per second at the surface of the ocean which then bounce back up to the satallite; the time it takes to reach the satallite is collected as data and can then be read as distances. These radar pulses detect fluctuations in the height of the ocean and variations in the gravity field which can then be used to infer variations in the height of the sea floor.

2. a)An image of this size will have 186,624 pixels

b)It is approximately five times the size of the uncompressed image file;

so it will have 933,100 pixels.

c)????

ALISON

1. It is possible to "get pictures of the sea floor by measuring small changes in the level of the of the sea surface" due to gravity fields. Smooth dips and valleys have a low gravity field, whereas peaks and ridges have high density fields. The level of the ocean is reflected from the gravity fields below. By measuring the heights of the sea surface, scientists can get a good idea of what is below. For example, a large underwater volcano would have a high density field and cause a depression in the sea level, whereas an underwater valley or canyon would have a low density field and cause a rise in the sea surface level.

2. During the summer of 1978, Seasat sent down a thousand radar pulses per second onto the sea surface that could detect changes on the surface from one to two inches, and then reported it back to a tracking system here on Earth.

3. If an image were to have 144 pixels/inch, and it was a 3x3 image, it would be (3x144)x(3x1440) or 432x432 pixels in the entire image. Or 186624 pixels in the entire image. A pixel is a dot, or spec, that makes up an entire image. The more pixels, the finer resolution there is in an image. The fewer the pixels, the less clear the image is going to be.

4. I have no idea how big the uncompressed image file with the above specifications would be. But I'll take a shot in the dark with 186,624 pixels!?

5. If the file size is kept the same, but the image is now 9x9 inches, there would be 1/3 as many pixels per inch, so there would be 48 pixels per inch and a very fuzzy image. I would expect it to be 1/3 the size because 3 is 1/3 of 9.

RYAN

1.it's possible to use the measurments of the changes in the surface of the ocean to predict the shape of the ocean floor. By knowing small changes in the surface one can ifer the gravitational pull inthis area which allows us to predict the height and density if the ocean floor in this area.

Seasat used a microwave altimeter to bounce pulses of radar of the surface of the ocean. In measuring the time that it takes for the pulse to return to the satellite it could calculate the distance from the satellite to the surface of the ocean. By comparing a graoup of these measurments it could show small changes in trhe height of the surface of the ocean.

2. 3*3 is the size of the image as it appears on the screen and 144 pixels per inch tells how many pixels are in one inch by one pixel high section of the image.

An image of the proportions stated above would be a total of 432*432= 186624 pixels

The same 186624 pixels shown 9in*9in would be 9x*9x=186624 x being the pixels per inch.

SHAYLA

you can get the image of the sea floor by bouncing microwaves off the surface of the ocean and then use the power serise expansion to calculate the effect of density and gravity pull on the ocean floor.

seasat used a radar altimeter which measures variations in the gravity field and thus the icean floor.

if an image is 3 in by 3 in and 144 pixels/in that means that if it was printed out it would be 3 inces but the computer recognizes it as being 864 pixels.

Im guessing like .5MB or 500k

it would probably be about 50 pixels per inch because it is just like stretching the image not adding more to it.

AMY

1. Haxby's map was basically created by using "Geosat 3" (a satellite) that generated pulses to map the small changes of the earth, and generate them into a picture of the ocean floor. It is basically plate-tectonics in motion.

2.Seasat fired off a thousand pulses of radar, generating 25-30 million measurements of the oceans surface.

As far as the next three questions go, I am not so sure of how to go about answering them... but I will try my best 1. If a 3x3 inch image has 144 pixels, there aren't enough pixels to make it a complete image because a typical inch consists of 72 pixels.

2. I am really unsure how to answer this question

3. There will be 432 pixels per inch because in a 3x3 inch image there are 48 pixels per inch, thus if there are 48 pixels per inch in a 9x9 inch image then there is a total of 432 pixels.

JON

1) It is possible to obtain pictures of the sea floor by bouncing radar pulses off of the bottom of the ocean, and then measure the differences in time that it took for the radar to return. By doing so repeatedly and recording the differences, we are able to arrange the changes so that a picture of the floor is produced. This method is similar to that of the voyager which bounced radio waves off the earth's surface.

The Seasat measured small changes in the sea surface by firing several radar pulses at the sea surface. The Seasat was able to send one thousand pulses at the sea surface every second. This allowed for the sea surface to be mapped with fine detail in a short amount of time.

2) If an object is 3x3 with 144 pixels per inch, than each inch of the 3x3 object would consist of 144 pixels

The image above consists of 1296 pixels

If the image were 9x9 with 144 pixels per inch, than it would consist of 11664 pixels.