Q & A's | Fun Facts | Cool Stuff to See |Cool Links |
San Francisco Bay: Change Detection and Mapping
Pictures Taken from Space Are Used to See Changes
in the San Francisco Bay Area!
The three images below are pictures taken from space of the San Francisco Bay area, California. Can you find San Francisco Bay on a map or globe? |
|
![]() What's a Change Picture?
The first picture (or image) was taken in 1984, the second in 1993. The third picture is called a Change Image Map. It was made by using the computer to compare the 1984 and 1993 pictures and mapping the changes that happened around San Francisco between 1984 and 1993!
What kinds of things can we learn from the change image map?
[TOP ] ![]() What do all the colors mean in the change map? The colors help scientists see the changes between 1984 and 1993!
Magenta - The magenta areas had more, bigger, or healthier plants and trees in 1984 than in 1993.
Green - This is the opposite of magenta. Green areas areas had more or bigger plants and trees in 1993 than in 1984. This shows up a lot in farming areas, where the crops are bigger, or the farmer has a different kind of plant growing in his/her field in 1993 than in 1984. Blue - Blue areas show where the city grew between 1984 and 1993. People built new houses, stores, factories, and other kinds of buildings. If you look closely in some areas, you can see the new building as a blue rectangle! White - These are areas where the Earth's surface is a lot brighter in 1993 than in 1984. For instance, the clouds in the 1993 satellite image show up white in the change image. Another thing that can cause areas of the change image to be white is ground which was burned in 1984 (so is very dark), but was recovering (growing new plants) by 1993. Black - This is the opposite of white. For example, areas that look black were burnt in 1993, or were new farmland that were natural areas (like fields and forests) in 1984. When farmers make new farmland, they dig up the dirt and turn it over. Dirt can be dark compared to plants, depending what color you are looking at. [TOP ] ![]() |
Show Me More! Here are somecloseupsof areas that changed a lot between 1984 and 1993. Each image shows an area in 1984, 1993, and the change image map.Zoomall the way in on the images, and pay special attention the the change image -
What changes do you see?
|
![]() South Bay Area | ![]() Carquinez Strait Area | ![]() Honker Bay Area |
U.S. Department of the Interior |
U.S. Geological Survey |
Jobs
Home | Search | Disclaimers & Privacy Web Rings Send comments to webman@TerraWeb.wr.usgs.gov URL: Last Modified: Thu Oct 31 15:08:18 MST 2002 | ![]() |