sea floor mapping lab
adapted from CIPE's Planet in a Shoe
box
Introduction:
Remote sensing is a process used by scientists to learn about
regions they cannot directly explore, such as the sea floor or a
remote planet's surface. The images of these regions are created
using sound waves that are then interpreted using a computer and
translated into images our eyes and brain can understand through
false color. These images are helpful to scientists looking for
understanding of a region for many purposes including geology,
archeology and biology. In the following lab students will use NIH
image software to create a false image of the sea floor that has been
created for them in a shoe box.
The Monterey bay area, with its rich and diverse biology and
unusual geology has been mapped by the USGS. To see this work click
here, Monterey
Bay sea floor imagery. After reading this page that describes the
process for sea floor mapping go to this part of the site for further
amazing images, some in 3-D, by clicking here
The Monterey Bay area is important biologically here are two web
sites to show you why. Monterey
Bay National Marine Sanctuary and Monterey
Bay virtual tour at National Geographic's website. Take time to
tour these sites.
Purpose:
The purpose of this lab is for students to experience a simulated
version of sonar mapping and false color image creation in order that
they may better understand the techniques of remote sensing and sea
floor mapping. The software we will be using has been created by NIH
image.
Pre- lab Questions :
these questions should be answered by students BEFORE beginning
the lab, usually done as homework the night before the lab.
- How could you map your bedroom without using your eyes?
- Before scientists had remote sensing instruments how might
they have mapped the sea floor?
- What hazards prevent scientists from directly mapping the sea
floor?
- Look at the images on the Monterey
Bay sea floor imagery. site, describe your impression and how
accurate they seem.
- Color your sea floor map to highlight the different features
of the sea floor and create a key to accompany your map. You may
want to look at the sea floor maps on the classroom wall.
Discussion Questions (to be done after the lab):
- What are the similarities and differences between your plotted
surface and the actual surface?
- How could you increase the radiometric and spatial resolution
of your image?
- What have you learned about sea floor mapping?
Extension Activities: (may be done for extra credit or a
portfolio)
- work in a team and tape a mystery object to the bottom of a
shoe box. Trade boxes then create maps and try to guess the
identity of you objects.
- compare your map with maps of Venus made by the pioneer and
Magellan spacecraft. The images are in the Venus maps
folder included with the activity images.
- create an imaginary surface using the Grid image and process
it to see what the surface would look like in 3-D.
Other Activities that involve remote sensing: (may be done for
extra credit or a portfolio)
ocean
color viewed from space -this activity looks at false color image
of the ocean to determine plankton bloom. Fun and interactive web
site!!
want some software for digital image viewing? check here
http://terraweb.wr.usgs.gov/TRS/software/mips/
or here the center for image processing
in education www.cipe.com.
To see more digital images of our planet, like a cool one of
sunset crater from a satellite click here
http://terraweb.wr.usgs.gov/TRS/software/mips/
and learn how to make your own 3-D glasses.
Procedure:
|
Building a surface
- Use the materials provided to create your own sea
floor bottom. Create a surface with as much relief as
possible to make your image more interesting. You are
using a fairly crude instrument for sensing. See
examples of good sea floors on the front table.
- Tape a copy of the grid on the lid of your sealed
shoe box.
- using a ball point pen or other sharp instrument
punch a hole on the center of every grid square, be
careful not to damage your sea floor while you are
doing this.
|
probe diagram
|
|
Making a measuring probe
- starting at one end of a small stick mark off
eight two cm segments on the stick. As shown on the
right.
- Color each segment, using eight different colors,
as shown at the right. R-O-Y-dk G-ltG-B-V
|
|
Collecting Data
- Follow the instructions given in class to launch
NIH image on your computer.
- Measure and record the elevation at each point on
the grid:
- Insert your measuring probe GENTLY into the shoe
box until it touches the bottom of the box or sea
floor.
- Measure the distance to the surface by reading the
color that is showing on the stick / probe as it
enters the hole. Think of the color as the time
required for the radio waves to travel to the surface
and back
- Record the color on a copy of the grid. Continue
until you have measured and recorded an elevation for
each square of the grid. When you finish, you have a
color coded elevation map.
|
|
Creating a color coded map
- Open the Map grid Image in NIH image
- Use your paint can to fill each square of the grid
with the color you recorded on your map
|
choose your colors from the LUT window
|
|
Producing a 3-D view
- now that you have a color - coded image of the
surface of the sea floor, you can see what it looks
like in 3-D.
- Use the paint can to change the black border and
grid lines to white.
- Filter your image to remove the grid lines.
- Drag a line across the image in any direction
using the map tool. This will create a profile plot
that shows what your surface would look like if viewed
from the side of your box. Try this several times in
different areas of your map.
- close all of your plot windows
- select your entire colored grid image
- make a surface plot of the elevation data.
|
Process/rank filters/reduce noise
Analyze / Surface Plot
|
|
Resolution
Your 3-D surface looks blocky because the resolution,
or detail of your map is very low. There are two kinds of
resolution, spatial the spacing between your measurements
and radiometric, the steps between the highest and lowest
measurements. Your measuring device, the stick was very
crude only having 8 steps. You can't improve your
resolution without redesigning your stick and box but you
can improve the way your image looks.
- Using the Process / Smooth tools smooth
your image.
- Make a new surface plot
- compare and repeat this process until you are
satisfied with your results.
|
Process / Smooth
|
|
Comparing with the real thing...
- Take the lid of your shoe box.
- Describe the differences that you see
|
|
return to top for discussion questions and
extension activities.