Grassroots Mapping

Yesterday we went aerial mapping a landscape that is just about to change radically : restoration of the oyster reef in Mobile Alabama, Dog river mouth – known as Helen Wood Park beach. In two hours from now (2011 January 22 6AM), hundreds of volunteers will come to install a massive oyster reef here. From 8AM today “Volunteers will be deploying approximately 23,000 bags of oyster shells to create new reefs and habitat at the mouth of Dog River” – see them in action here .

Aerial mapping Prof. Dawn McKinney & Prof. Leo Denton of the University of Mobile South Alabama. Thanks to Shannon Dosemagen for organizing the trip.

These are the different reefs and bags of oyster they are installing. 5 non-profit organizations are working together to accomplish this massive landscaping project.

We took about 5000 aerial pictures that I turned into 3 very large resolution maps to make one huge map (at the top of the post):

Download these full resolution maps to your computer as .zip file (27mb). If you want to learn how to make one of these map, check this post.

This time, in addition of aerial photography, I also took ground samples (~250x microscopy), sand, sediment, organic material taken at regular interval. The idea is : if we are able to say what is on the ground – sometimes we may find oil spilled still – we can qualify and quantify what we see on the aerial pictures. We will come back in a few weeks to map again and see the effects of installing an artificial oyster reef here : “before and after” 🙂

—
Original blog post : http://cesarharada.posterous.com/mapping-river-dog-mouth-mobile-alabama
date : 20110121@15:41, low-tide.
Location : 30.57562, -88.07847
Mapping for Grassroots Mapping & LA Bucket Brigade.
Photos : Prof. Leo Denton and Prof. Dawn McKinney
Stitching : Cesar Harada
Left at 10:45 – return 20:30
Milleage : start 761963 – end 764803

This post was written by Christopher Johnson, a student at South Alabama University that participated in the Grassroots Mapping project in Alabama.

Hello! My name is Christopher Johnson, and I was one of the University of South Alabama (USA) students to participate in the Grassroots Mapping project in Professor Dawn McKinney‘s Computer Science class. It was a bit weird to go outside and do a project, since our majors are all computer-related, but I think in the long run the class was better for it.

Basically we were broken into teams of around six, each team having at least two of each major: CS, IT, and IS (not our actual majors; we were assigned a major for each third of the course, which we rotated). We had to work in teams to stitch together parts of Dauphin Island using Cartagen, among a few other things essential to the Freshman course.

Most of the technical problems came with Cartagen being down for a short period and unusable pictures – the nice sea breeze can be a difficult adversary. Another difficulty was overcoming the challenges we created ourselves, such as arguments within the group and people not showing up for class.

Overall it was a very good learning experience; I was one of those who went to Dauphin Island (taking the pictures was optional), and we had a lot of fun. I’d definitely do it again, given the opportunity, and I recommend that everybody go out there and try to make a difference. It’s more fun than you think, and you can really make a difference in your community!

Mission

A group of students attending Western Carolina University, under the guidance of Adam Griffith, took on the project of mapping the campus using aerial photography in the fall of 2010. The project was initiated because there was concern about the Google Earth images that covered the campus and the surrounding Cullowhee area. Satellites for Google Earth images only pass by every couple weeks and our campus is experiencing lots of change through construction of new buildings and new facilities that Google Earth does not reflect. Also, the images are of extremely poor quality, and unless you are familiar with the campus it is difficult to discern cars and some buildings and small structures.. This is where we come in: our images taken only 1000 feet in the air are of much better quality and clarity than those in Google Earth, and when we complete the project we would love for Google to insert our images into their maps.

Process

The photographs were taken by suspending a camera inside the top of a 2 liter soda bottle and attaching this setup to a 250 gram balloon which was on 1000 feet of string (see materials picture d). We also used the same soda bottle-camera rigging attached to a kite to test which produced better photos (balloon). The balloon was pulled by hand by students on the ground and was navigated around campus, making sure to steer clear of tall buildings, trees, and other high objects that could snag the string. The camera was 14 megapixels and was set on continuous mode so it would take about a picture per second while up in the air. After several flights, we discovered what conditions were most suitable to our endeavor. The best photos were taken when the sun was out with no clouds in the sky. Lights winds were fine, but heavier winds caused the balloon to be jerked around, which would not allow the camera to focus. Advice for other mappers would be that no matter what equipment you use to take your aerial photos, make sure it is sturdy enough to withstand a fall! We experienced a malfunction where the balloon burst while we were pulling it in, and the camera struck pavement roughly. Luckily it survived with little to no damage.

Stitching

When first reviewing the outline of the project, stitching the photos together to form the map seemed like a simple enough task. We found out otherwise. The photos chosen had to be almost completely straight down and in focus on the area being photographed in order for them to be properly stitched together to fit Google Earth. Because the camera was in so much motion while in the air, there were very few pictures that turned out to be completely straight down. Due to this fact, we had to warp several photos when they were stitched and manually force them to mirror Google Earth. Stitching these photos turned out to be the most difficult and time consuming task for the whole project. However, our end product was such an improvement over Google Earth that the effort was worth it. Our photos had about 7cm resolution or 7 cm per pixel, which is a vast difference from Google Earth.

Over the last four months, the Gulf Coast contingency of Grassroots Mapping has been working with the University of South Alabama (USA) School of Computer and Information Sciences. Dauphin Island community member, Leo Denton, introduced us to USA Instructor, Dawn McKinney in September and she requested that we set up a project that would help her freshmen students learn about the process of aerial mapping, project management and using open source software to stitch maps.

During the first session, Jeff Warren and I gave an overview of the Grassroots Mapping project and Jeff taught the basics of map stitching via Skype from Boston. After this first session, with two volunteers, I accompanied a group of approximately fifteen students and three faculty members to Dauphin Island for a day of service learning where students were to map different portions of the island. Dauphin Island is a particularly difficult location to map as we had experienced over the course of the summer. On the ground there can be hardly a breeze, but upon letting a balloon up only a hundred feet, the wind currents change and you can end up with a balloon floating low to the ground, but half a mile from your standing point. Using the kite was equally difficult, two or three students would act as shadows, making sure that upon catching a rogue air current the kite and camera didn’t dive into the water. Despite the initial difficulties that students experienced, they mapped the island a total of three times, producing enough images to experiment with the stitching process.

From participating in the mapping and learning about Grassroots Mapping techniques, students commented that, “… it gives our communities a chance to fight back,” and, “We were basically able to make our own Google Earth. It made us realize that we don’t always have to rely on companies or what they say. This process gave us the confidence to do things that we might have thought were too complicated or troublesome- you can really do so much with relatively little.”

In the classroom, the students used the mapping process as a way to experiment with project management. In each team, students were required to break into the roles of IS, IT and CS, each with different responsibilities. You’ll be hearing from a student in the class on his experience with this project in the next week, but overwhelmingly when students were asked to reflect on what the most powerful take away from this project was, the response was that they not only learned mapping and computing techniques, but skills for working and communicating with a team.

Student teams tackled difficulties that they encountered along the way and even developed suggestions for the Grassroots Mapping team going forward. An initial difficulty that students learned to work around was that the shoreline of Dauphin Island had been completely altered after Katrina, the beach of Dauphin having expanded close to 200 feet. Although Google imagery documented a central pier as being underwater, students quickly identified from memory their local shoreline, noting that it was the same pier that today stands completely inland, out of the water and offers shade on the hot summer days to beach goers.

When the Cartagen site was down for a few weeks, students experimented with different programs that could help them stitch maps including Gimp, Photoshop and Windows Live Photo Gallery. Students favored alternative methods such as the automatic merge function in Photoshop, but were quick to point out the flaws with the different systems that they tried. Some suggested that ease of stitching did not equate to accurate maps, others cautioned their classmates that working in Photoshop was difficult because of the amount of memory that was used in the process. Others even made suggestions about the mapping process including:

– tie two (or even better, three) strings to the balloon to control the movement rather than letting the wind dictate balloon direction,

– When in auto shoot function, count how long it takes for the camera to snap 100 pictures and take GPS coordinates at each subsequent time interval so that there is a more accurate GPS reading (when logging and tracking devices are unavailable),

– Because it is difficult to geographically pinpoint photos where only beach shows, have someone shadow the balloon to take GPS coordinates while walking underneath.

After a positive experience with this project, which was interpreted into computing management practices, USA is interested in continuing this program next semester. From the teaching perspective, Dawn commented that, “…it was wonderful to get out of the classroom and have an experience with my students, it not only gave them a hands on opportunity away from their computers, but also allowed me, as an instructor, to get to know each of them better.” As this was a “pilot” program for teaching Gulf Coast students about the Grassroots Mapping process- from mapping their local areas, to completing final mapped images- over the next few months, we’ll be working on further developing the teaching process for computing students.

Thanks to everyone who helped with this project- all the students, Leo Denton, Dawn McKinney, Cesar Harada, Hunter Daniels and Mariko Toyoji

On October 20th, architecture students from Hong Kong university gathered at Studio X Beijing to assemble their own grassroots mapping kits and take them out in the city. The students were in Beijing on their site visit, studying the city’s 2nd ring road and envisioning it as a new urban public space in 2049.

We spent the morning in Studio X, constructing camera rigs, taping mylar emergency blankets into 4 pillow-shaped balloons and filling them with helium, and imagining other forms of active mapping. After a spicy lunch at the restaurant next door, we headed out and started marching from the little historic hutong where the studio is located, into Beijing’s infamous traffic.

We first gave our kites a try, but although they city has a great kite tradition, there was not enough wind and our kites refused to get off the ground – even with the help of some experienced kiters we met in the park. Turning back to our balloons we ran some test flights, and ended up connecting them into pairs (tying top and bottom and wrapping with tape in the center), and when that wasn’t enough we tied the whole thing together at the bottom.

The weather was almost perfect – chilly and calm with very little wind. We ended up not going very high, faced with an interesting dilemma – a narrow angle with sharper, more saturated images, vs. a wider angle with a foggier, smoggier image? (yes, there is always photoshop).
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A little map we made was on display at the Art Spill expo in New Orleans along the great pictures of LA Bucket Brigade volunteer Hunter Daniel. There were many visitors. Art Spill: Disaster, art, activism and recovery 6-7:45
Art Spill exhibit closing 7:40-10.

Update: I started to stitch the flight imagery together using the Cartagen Knitter — anyone who likes can help out by adjusting and uploading new images: cartagen.org/maps/gigapixel-cmu

We had a great time flying at the workshop I gave on Saturday (above photo courtesy of Andrew A. Wagner); Nathan Craig was there with some kites and I got to check out his very nice kite aerial photography kit. He uses the same electric cable winder I do!

The conference was centered around the GigaPan tool, and so I learned a lot about 3D reconstruction of a scene from image collections… I hope to duplicate some of their techniques to derive 3D terrain maps from our balloon photos!

Here is a link to the entire set of aerial images we shot: gigapixel-workshop.zip (1 Gb)

And here’s one of the aerial photos we shot:

The flights were typical of DIY Cessna imagery collection. The Camera is held in approximate “geodata position” by a rubberized cabinet clamp. The camera operator stays quite busy though by holding the rig to dampen vibrations, shooting images, and communicating with the pilot. All this is happening with the window wide open and the plane travelling around 130 MPH, making it quite noisy in the cabin.

Google Earth and imagery within the historical time slider was used concurrently with other existing imagery sources from the region to process the new data from the flight. The map contains oil pollution/dispersants.

-video of mapmaking

-imagery on Flickr -original TIFF file

* UMO = “unidentified mapping object”

On the morning of Friday October 8th, the Grassroots Mapping public workshop kicked off in the corner gallery on 5th avenue and W 13th Street. We began experimenting with a few types of mylar ranging from 55″ 1 mil rolls to 0.5 mil emergency survival sleep sacks, in shapes ranging from a tetrahedron to what some referred to as the “burrito.”  Seams were folded and taped, then pressed with a pen or ID card. We worked all day to assemble four rigs between the two dedicated Parsons/Eugene Lang classes and bring together materials for the exhibit and for Saturday’s workshop. Fun fact: New York taxis will not pick up a 5 foot tall tank of helium.

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This weekend in New York City, public workshops will be held at 2 West 13^th Street, in the corner gallery on 5^th Avenue. Come out and join us! The exhibit and events are sponsored by Urban Inclusions, a  collaboration between Urban Design at Parsons the New School for Design and Urban Studies at Eugene Lang College. Additional thanks to the students of Mapping the City and Street Life.

Friday October 8, 9am-12pm, or 2pm-5pm:

Hack a camera and assemble a rig (2 West 13th Street)
Saturday October 9, 1pm-5pm:
Collect imagery with balloons and kites (2 West 13^th Street, Union Square)

Email ebarry at gmail for further information.

(Image above is from a Spring 2010 balloon mapping workshop at RISD)