Week 12: Do You See What I See? Stereoscopes and Satellite Images

This week in "Eyes in the Sky" we all tried our luck at satellite image interpretation.  By looking at two photographs of the same area (one for each eye), a two dimensional image can appear three dimensional. In order to only see the picture, Dr. Suresh brought in pocket stereoscopes used by the army back in the 1940s.  These allow the eye to focus only on the pictures, just like how horse eye flaps keep them going on the right path.  Dr. Suresh also brought along a ton of different double printed black and white aerial photographs of areas all around the United States taken around the 1960s. Our job was to look at the image in 3-D using the glasses and identify different signifying features from the photo. Since my computer is acting up and not allowing me to post pictures to blogger, I'll just describe the 5 aerial images I decided to look at:

Diamond Head, Hawaii

In this photo, there is a large crater in the top right hand connected by a ridge to a more eroded
mountain in the lower left hand corner.  The mountain is heavily built up with houses all the way up
to the top. The rest of the landscape is taken up by rolling hills that go down to the ocean edge.  I've actually climbed to the top of the diamond head crater, so it was interesting to see it from the sky.

Manhattan, New York

The largest buildings dominating the landscape from the time of this photograph are the Empire State Building and the Chrysler Building.  Although it's hard to see how high a building is from above, I could still tell how high the buildings are by the length of the shadow they cast. There is a definite grid pattern made by the streets of the city.  In the upper right hand corner, there is a harbor filled with shipping liners.

Black Dragon Canyon, Utah

The area is filled with deep gullies.  The jagged rocks forming the canyon are stratified in different layers.  A river runs from the upper left hand side of the image downward through through the large gulley on the left side.

Mt. Rainier

There is snow on most of the mountain, and vegetation starts at the base of the mountain.  A road winds along the mountain at the top of the image.  The peak pictured in the image is circular, meaning the mountain may have been a volcano.  I've been to Mt. Rainier as well, and when I went in June, there were almost 20 feet of snow still on the ground.

Longs Peak, Colorado

The peaks are very steep, carved by glaciers. There are three peaks and two valleys. The valley at the bottom of the photo is filled with debris. There is no large sign of vegetation in the entire image.  This may be because the mountains are at too high an elevation to grow many plants.   

Though I found these pictures fascinating, I don't think I could hold a candle to those who did this for a living — I felt like I was going blind after only about 30 minutes!

Week 11: Fun with Movies

This is the finished product of an experimental video made with Adobe Premiere Pro CS6.  I made this video with fellow classmate Emily Toupin.  We put together a compilation of satellite images, briefly explaining both their scientific and artistic significance.  Though I've made my fair share of iMovie projects, I have never worked with this software before, so it was a good learning experience. I now feel prepared to create a 10 minute video as my final project for the class, investigating how satellite imagery can aid in social justice and war crimes.  Enjoy the video!

Week 10: Drones and Big Brother- Who's Watching You?

Most likely, you’ve gone on Facebook, Twitter, Instagram, or some type of social media today.  Think of all the information you put out into cyberspace: credit cards for shopping, personal information for online banking, and loads of information from email and other messaging.  Since the dawn of the personal computer, society has gotten more and more connected.  Most people share their day-to-day activities with more people online than those they interact with in reality.  As our lives and personal information become more and more intertwined with the Internet, questions start to arise over privacy rights.  The capability to find any information in cyberspace is out there, but who should be allowed access this information and at what times?  This Wednesday during class, we watched Enemy of the State, where these privacy questions are explored.   

 

http://pixshark.com/enemy-of-the-state-dvd.htm

In the movie, the leader of the National Security Agency (NSA) Thomas Brian Reynolds wants to pass a bill, and he kills a politician who has the ability to stop the bill from passing.  In order to cover up his wrongdoing, Reynolds uses all his powers, from satellites and trackers to online hacking in order to cover up his tracks, killing numerous people and smearing the name of a prominent lawyer.  In the end, the truth is exposed, but the question of personal security remains, summed up in the movie quote by Larry King: “How do we draw the line—draw the line between protection of national security, obviously the government's need to obtain intelligence data, and the protection of civil liberties, particularly the sanctity of my home? You've got no right to come into my home!”  In the movie there is dispute over the use of satellites to spy on individuals, but in current events drones have started to raise alarm over privacy issues.  Unlike satellites that have to continually be in one orbit, drones are able to hover over one spot and travel any way the controller wishes, making them a potentially much more efficient and useful tool for spying.   

 

A commercial drone and a drone used by the US Army

http://jurist.org/feature/featured/drones/ 

http://dronesafetycouncil.com/

The United States has placed strict rules on drone use, but other countries of the world are much more relaxed.  Are drones a hazard to public safety, or has the danger been over-dramatized?  The opinions on this matter run the gambit, but I believe it’s important to know the regulations concerning drones before deciding if they pose a threat or not.  In order to fly a drone, the user must get a Certificate of Waiver or Authorization from the Federal Aviation Administration.  UAVs for recreational purposes are only allowed to fly below 400 feet and must remain within eyesight.  In the government, drones are only officially able to fly in a certain areas.  The question remains, how are these strictures enforced?  As history has shown, tremendous power can lead to tremendous corruption.  In order to keep protect personal privacy, we have to make sure we keep those that hold great power in the future in check.

Week Nine: Taking to the Skies

This week during lab on Wednesday our class put action to all we have learned about aerial photography, taking to the skies with balloons and cameras.  The seminar class split into different groups, and we each had separate research projects and aerial balloon camera designs.  For my group’s aerial photography project, we decided to study the use of footpaths on the Furman campus around South Housing and the Lakeside Judson dorm.  During our time at Furman, my group members and I have noticed that many of the walking paths at Furman are not used, and students decide to take the most efficient path instead.  By collecting aerial photograph data during a class change, we could identify student-made paths with heavy foot traffic and the paved paths that not many people use.   

The main areas where we planned to collect aerial data

When the day came to actually collect the data, most of the groups decided to lift their camera into the air with many, many party balloons.  My group partnered with another team and ordered an aerial photography balloon kit online, so we used a very large balloon almost 2 meters tall when inflated.  The balloon kit also came with zip ties, carabiners, rope, gloves, rubber bands, and a rubber ring; everything to help get the balloon in the sky.  Although the balloon came with everything we needed, we had to build our own housing for the camera.  To make it, we cut out the top of a 2-liter bottle, and using rubber bands, suspended the go pro camera inside it.  We used a large can of helium from Dr. Suresh to fill up the balloon.  We had to inflate the balloon separately three times because we underestimated the amount of helium it took to lift out camera in the air.  Finally, the balloon was strong enough to lift the go pro. 

The group we were sharing the balloon kit with needed to collect data on tree removal on the mall, so we took the balloon first to the large circular lawn in front of the PAC.  In order to avoid trees, we planned to release the balloon in the open lawn area until it reached above tree level then walk through the mall.  Everything was going as planned as we walked through the mall when SUDDENLY a gust of wind blew our balloon far to the left.  After that, the balloon sunk back below tree level, and the camera holder became stuck in a tree.  We tried to get the balloon back down to no avail, so we decided to call campus maintenance.  Seeing that the official induction of the new Furman president was the next day, the maintenance team was eager to remove a giant, red rubber balloon from the middle of campus.  After a long while of waiting and the use of a cherry picker, we were able bring down a popped balloon and an intact go pro.  Though my group was not able to do our research, the other team gathered an innumerable measure of data on tree branches.  

 Next week, Dr. Suresh is going to take my group out with a drone, so we can collect our data.  Although my group spent most of its time trying to get the balloon out of a tree, I learned valuable information about how to get a balloon in the air and how difficult taking aerial photography really is.

 

Week Eight: Viva la Resolution!

Over the weeks we've figured out different things about remote sensing with satellites: their precursors, their uses, how they orbit in Earth, and the electromagnetic radiation they pick up.  The question still remains, how does a satellite pick up this information?  How can one satellite see heat while another sees infrared light, or more broadly, what creates differences between satellites?  Some important distinctions between satellites are their resolutions. 

There are four different types of resolution concerning remote sensing: spatial resolution, spectral resolution, radiometric resolution, and temporal resolution.  All these factor in to the type of information a satellite is able to gather, and they are important to further understanding on how satellites really work.

Spatial resolution is one of the simplest distinguishers between satellites.  It is basically the smallest feature a satellite is able to distinguish.  This is also the pixel size of an object.  An example of spatial resolution that I’m sure almost everyone reading this has experienced is whenever we try to make a picture bigger, and it turns into a blur of squares.  An easy way to think of spatial resolution is that the bigger you can make a photo without it turning into squares, the higher the spatial resolution.

 

high spatial resolution → low spatial resolution

Source: http://coast.noaa.gov/geozone/you-say-you-want-high-resolution/

 

Next, spectral resolution determines what types of electromagnetic wavelengths a satellite can pick up.  The finer the spectral resolution, the smaller waves the satellite can distinguish.  This is the difference between black and white film and color film.  Black and white film lumps all the different colors together and sees them as either black or white.  Alternately, the finer resolution of color film allows the sensor to distinguish between different colors.

 

                                       

 Different spectral resolutions

Source: http://www.nrcan.gc.ca/earth-sciences/geomatics/satellite-imagery-air-photos/satellite-imagery-products/educational-resources/9407

Radiometric resolution relates to spectral resolution concerning the quality of a satellite image.  Spectral resolution determines the amount of pixels in an image, but the radiometric resolution affects how the satellite discerns differences in energy (think of shading in a photograph being either very gradual or very abrupt).

                                       

Examples of differences in radiometric resolution

Source: http://www.slideshare.net/merdevie/remote-sensing-10526190

Lastly, temporal resolution is the amount of time it takes a satellite to pass over the same place on Earth again.  This is important for what purpose the satellite has.  For a LANDSAT, the temporal resolution is 16 days.  If we want to see a real time event from the air, then we would want a satellite with faster temporal resolution.

Bibliography:

Intermap Technologies Ltd. Tutorial: Fundamentals of Remote Sensing. Ottawa: Canada Centre for Remote Sensing, 2013. Print.          

 

 

Week Seven: The Science behind Electromagnetic Waves, or How in the World Does the Radio Work?

You're driving in your car, and you turn on your radio.  Suddenly, Bruno Mars is belting out "Uptown Funk" while you dance along.  In this day and age, no one really questions if or how a radio emits the specific sounds that make up our most beloved Top 40 songs or favorite NPR talk shows, but when you think about it, the concept of radio waves, or any type of electromagnetic waves for that matter, are quite an abstract concept to think of.  Anything we see or hear relies on these strange waves that almost everyone is so familiar with but knows nothing about.  Remote sensing relies on these electromagnetic waves.  Actually, organs like our ears are really remote sensing tools that allow us to pick up sound waves.  This week, we delved into how electromagnetic waves work and allow remote sensing to be possible.

First, what is electromagnetic energy?  Also known as electromagnetic radiation, this is energy emitted in the form of waves that is released from anything over 0° Kelvin, or -273.15° C.  The sun is the main source of electromagnetic energy, but virtually everything around us emits some type of electromagnetic energy, including ourselves.  All the different types of electromagnetic energy lie on the electromagnetic spectrum, this includes the different waves we perceive, such as color and radio waves, as well as the "invisible" waves such as infrared and X-rays.

  

Source: http://butane.chem.uiuc.edu/pshapley/GenChem2/A3/3.html

 

So there are all these waves flying around us willy-nilly? No, there are rules to how these different waves act in nature.  First, each type of wave has a different period, or time it takes to go through one wave revolution (think of following the line up a hill and down a valley; that's one period).  These wavelengths are measured in nanometers.  The amount of nanometers a period tells us the frequency of a wave.  The shorter the wave, the higher the frequency.  The amplitude, or height of a wave is another defining characteristic that allows us to differentiate between types of waves. Using Planck's Radiation Law, we can find the wavelength (basically what kind of wave) emitted by a blackbody, or anything that absorbs all light that hits it then re-emits energy back (Photovoltaic Education Network).  I'm trying to keep this entry simple, so I won't explain the equation that let's us figure this out, but I'll still show it:

 

Source: http://csep10.phys.utk.edu/astr162/lect/light/radiation.html

Basically, Planck's Radiation Law (the above equation) proves that for every fixed temperature, there is a fixed wavelength (Radiation Laws).  Some other related laws that help to explain the behavior of electromagnetic radiation are the Stefan-Boltzman Law and Wein's Displacement Law.  The Stefan-Boltzman Law tells us the total energy emitted from a blackbody (Radiation Laws).  From Wein's Displacement Law, we learn that temperature and peak wavelength are proportional, because their product remains constant.  This allows us to find out the temperature of different blackbodies based on their wavelength (HyperPhysics).  

 

Source: http://csep10.phys.utk.edu/astr162/lect/light/radiation.html

 

Using all these laws, we can determine the behavior of different wavelengths across the electromagnetic spectrum.  This is important in remote sensing, because we are able to use this information to manipulate different waves.  One basic example of this manipulation is in FM and AM radio.  FM stands for "frequency manipulation" and AM stands for "amplitude manipulation."  This allows us to make certain sounds come over different channels on the radio.  Thanks to the science of electromagnetic waves, we are able to pinpoint and collect different types of data from satellites. So next time you're jamming out in your car, take a second to think about the amazing science we often take for granted in electromagnetic radiation.

Bibliography:

HyperPhysics. Ed. Carl R. Nave. Georgia State University, 2012. Web. 26 Feb. 2015. <http://hyperphysics.phy-astr.gsu.edu/hbase/wien.html>. 

Photovoltaic Education Network. Ed. Stuart Bowden and Christiana Honsberg. Arizona State University. Web. <http://pveducation.org/pvcdrom/properties-of-sunlight/blackbody-radiation>. 

"Radiation Laws." Astronomy 162. University of Tennessee, Knoxville. Web. <http://csep10.phys.utk.edu/astr162/lect/light/radiation.html>.