New three-dimensional radar and hi-resolution aerial images of Port-au-Prince and the surrounding areas released starting Friday could boost both recovery and research efforts in Haiti in the wake of the magnitude 7.0 earthquake that struck on Jan. 12.

Satellite images and aerial photos have been important resources, but the flatness of those images makes it hard for viewers to identify what they’re looking at.

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"We have dozens of points located along [a satellite image of] the fault with annotations after these points saying things like, 'I don’t know. This may be a footpath or maybe it is a fracture,'" said U.S. Geological Survey geophysicist Ken Hudnut, who's been trying to map the Enriquillo-Plantain Garden fault that caused the earthquake. "With the resolution of the [old] imagery … it's hard to be conclusive."

On Thursday, remote-sensing scientists from the Rochester Institute of Technology in New York began collecting new aerial images of the Port-au-Prince area. They're using a twin-engine Piper PA-31 Navajo that houses numerous sensors, including a light-detection and ranging, or LiDAR, instrument that generates the 3-D data. It has a camera that shoots with enough resolution to make out cars and occasionally people and multiple infrared instruments that sketch out details invisible to the naked eye, such as hidden sources of heat and water.

The preliminary 6-inch resolution data shows enormous refugee areas dotted with brightly colored red and blue tents. "You can’t miss them," said Stefi Baum, director of RIT's imaging-science center. It also shows rubble piled precariously along hillsides, which could amplify the threat of mudslides. "Everything is OK until the rainy season," Baum said. "But then all of that rubble will just flow down those structures."

The data they gather will also help identify access roads that have been cut off by debris, broken bridges and unstable buildings that remain standing, as well as provide much clearer images of the fault, said RIT remote-sensing specialist Jan van Aardt, one of the project’s coordinators.

Scientists studying Haiti are most excited about the LiDAR instrument, which emits a pulse of light and then measures how fast that light takes to return to the aircraft. Because data from taller points will arrive faster than data from lower points, the points stitch together to form a 3-dimensional snapshot of the scene.

"You can almost hold up your fist in the middle of the air and assign it an 'X' a 'Y' and a 'Z' [coordinate]," van Aardt said. "You can think of LiDAR data as millions of such positions … each with an X a Y and a Z coordinate." Those points will also be tied to geographic coordinates to help people pinpoint specific locations on the ground.

In the image below and the image at the top of the post, the first point hit by the LiDAR is shown. Blue represents lower surfaces, green is higher.

Sorting out the logistics of the $200,000 World Bank-funded project has been challenging, van Aardt said. Because of limited air space in Haiti, the team will be based in Puerto Rico and refuel every four hours in the Dominican Republic. Every night, researchers at the University of Puerto Rico will help the RIT team transfer the aerial images to Rochester and the huge LiDAR data files to Kucera International aerial imaging company in Ohio, where they will be processed. Then the images will be made public.

Companies, such as GoogleEarth, Microsoft and Yahoo, have all expressed interest in uploading this data, said Ron Eguchi, CEO of ImageCat, a California-based company that specializes in disaster management, and an RIT partner.

Because RIT's team plans to assess damage in Port-au-Prince first, Hudnut will likely have to wait a day or two to receive images of the Enriquillo fault, which lies just outside the city. The new data could reveal major ruptures along the fault. With no such ruptures currently visible, Hudnut and his colleagues are worried that the ground beneath Port-au-Prince remains under a great deal of stress that could potentially trigger another, even larger earthquake.

"Our dour view of the situation is that it looks like where the fault broke is pretty far to the west and we're now concerned that it didn't rupture in the eastern part," Hudnut said.

Because the possibility of another major earthquake of equal or greater magnitude remains low – around 3 percent over the next 30 days – even if no major ruptures are found, researchers hope to use these images primarily to create computer models that show how the fault has behaved in the past and how it might behave in the future.

For instance, about five years ago, researchers used LiDAR data to map the San Andreas fault in California. Scientists had previously concluded that an earthquake in 1857 caused the ground to shift 30 feet. But the LiDAR data made clear that the shift was caused not by one, but two, earthquakes.

"Past earthquakes … leave their imprint on the Earth," said Eric Calais, a geophysicist at Purdue University. LiDAR data records those imprints, such as distinctive fracture patterns in rock and furrows in the topography of the land. Scientists should be able to use the Enriquillo images to predict the strength of future earthquakes and calculate how often the fault has ruptured in the past. "Then this information can be used to prepare a city, prepare a country," Calais says.

The LiDAR images above, below and on the following page are of the National Palace, added on 01/24/10.

In this image, all features on the landscape have been removed, including the palace, fountain, and trees. This depicts variations in the bare earth.

This is a high-resolution aerial photo of Port-au-Prince showing a roof marked with an an appeal for help.

Images: Rochester Institute of Technology Chester F. Carlson Center for Imaging Science.

See more 3-D LiDAR image on the following page.



This overhead view of the presidential palace and fountain depicts the first point that the LiDAR hit. The blue represents the lowest point in the image. The greens, reds, and browns are all different heights.



This image depicts the same data as the image above, but the perspective is different. Instead of looking straight down at the palace, the viewer is observing the scene from an overhead angle. The points have not been connected to form a surface.

This map depicts variations in brightness of surfaces.

This image shows the bare earth beneath the palace viewed at an angle.

This is a high-resolution aerial photograph with 6-inch resolution.

Images: Rochester Institute of Technology Chester F. Carlson Center for Imaging Science.

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