Name Stephanie F. Period 4
SATELLITE IMAGERY TEST # 2 PART A
Answer all questions as completely as possible. Remember you are demonstrating your understanding of these concepts.
REMOTE SENSING
We have seen many problems using remote sensing, so it has made us realize what we are doing to planet earth. It has also showed us a big picture of the entire Earth. We know realize how big and beautiful it really is. Since remote sensing is looking at things from a distance, we can look at our planet from space, a birds eye view, and not just from outside.
2. Based upon the video "Mission to Planet Earth" describe how remote sensing can be used to understand a problem facing humanity today.
Remote sensing has showed us many global problems that we are facing today, one of which is deforestation. Deforestation is the destruction of our forests. By using remote sensing, we can see a birds eye view of the entire forest, so we can see how much and how rapidly it is being destroyed. For instance, in the Amazon, farmers need to cut down trees, but they are slowly demolishing the forest. Also the annual rains didn't come to put out the fires this year, so they continued to burn. By using microwave sensors we can see through the clouds and smoke, to see how much forest we have lost, and how much we have left.
3. A. Interpret the following graph.
This is a spectral signature chart. It shows you the percentage of reflectance for different objects at different bandwidths. When assigning false colors, this chart is very helpful. It shows you what color to pick, so that the object will show up best, based on the percentage of reflectance.
In this graph, grasses have the highest percentage of reflectance in the infrared bandwidths, so it will show up the best. Asphalt does not really show up that well in any color. To contrast colors, you could pick infrared for grass, and green for concrete.
3. B. Describe how this graph could be used to select bandwidths to image different objects.
By using this graph we can see the objects at different percentages of reflectance at different bandwidths. It shows us at which bandwidths the object will stand out and be brightest or darkest, based on the percentage of reflectance.
It also makes it easy to contrast images, because you can pick two different colors, and still be sure they will show up because of the percentages of reflectance.
4. Explain the three steps in the process of creating a false color TM or MSS image.
You need to first sensor three images by using a Landsat satellite camera. Then assign each gray scale image a color, based on your results from your spectral signature. Such as picking green, red, and black, or purple, or yellow, or infrared, or gray.
When the three are superimposed or stacked on top of each other, they will create one false color image.
RADAR IMAGING
5. A. Explain what radar imaging is and why is it an active system.
Radar imaging is getting images by using microwave signals. You send a signal to the earth, and it hits the earth, then bounces off back at the satellite. This is an active system because the signals themselves are moving and bouncing back.
Digital radar images are created by taking a microwave signal image, and assigning the image dB or decibel values. They are just like brightness values assigned to pixels. In order to get those pixels you have to change the image into binary code, (1 and 0) and then decode it.
6. Describe THREE important reason radar imaging is used.
Radar imaging is used to show maps and places with clouds because microwave can see through clouds.
Also because you can tell how rough or smooth an image is because of the back scatter range.
Lastly because radar imaging also picks up water, snow, and ice very well. You get a lot of different colors to show the amount of water.
7. Explain how different polarizations can be used to generate a false color radar image.
Three different polarizations, HH, HV, and VV, can be used to generate a false color radar image. H stands for Horizontal and V for Vertical. Putting the three together is just like putting R, G, and B together instead its HH, HV, VV. This equals one complete polarized image.
8. A. Explain what back scatter is.
Back scatter is the reflectance or signal after it has touched the surface and is bouncing back to satellite. The amount of back scatter shows how smooth or how rough a surface is.
8. B. Using the handout, explain how back scatter can be used to differentiate between urban (city), agricultural and forested regions in order to study how the balance between the three has changed over a 10 year period.
Back scatter tells you how smooth or rough the surface is. Very high back scatter is very rough, bumpy, or wet surfaces. This can show you the change over 10 years. By radar imaging a forest, then checking it in 10 years. If the back scatter is higher, the forest is denser, if the back scatter is lower; the forest is less dense then it was before. The forest also could be drier than before, such as it could have been flooded at first.
Same with cites. You can see more or less buildings, by receiving more or less back scatter, and double bounce. Double bounce is when the signal bounces off one object, but before returning to the satellite it hits another object.