Interpreting Airphotos in the Field

Yesterday, students in the Aerial Photo Interpretation class (FORT 230) visited selected sites on the aerial photos they are studying. Using the principles of interpretation: shape, shadow, pattern, association, texture, tone/color, and relative size, they compared the scene on the photo with what is actually on the ground today.

Given that the sets of photos we are using were taken in 1977, the element of time must also be included in the interpretation. Some areas have been harvested and others have grow in from previous harvests. Little of the area has changed through human use, however.

Here is a Google map of the sites the class visited:


View Larger Map

Digital pictures were taken at each stop and then geotagged with the location coordinates. Follow this link to see the geotagged images on a Yahoo Map in Flickr. Picasa albums also offers geotagging on a Google map as shown in this link. Each provider and format has its own advantages. There is probably a universal tool out there to combine these into one view.

Russian GPS: GLONASS

Business / World Business

Russia Challenges the U.S. Monopoly on Satellite Navigation

By ANDREW E. KRAMER

Published: April 4, 2007

Russia plans to launch eight navigation satellites to compete with the Global Positioning System operated by the U.S.

This New York Times article describes the Russian effort to complete its own GPS system, called GLONASS, by launching eight more satellites. This would make it operational over the Russian land mass and nearby countries. The network is seen as a competitor to the US system and an effort to bolster Russia's prestige. Many countries fear reliance on an American system in case of problems in international relations. The article says that the European system, Galileo, is stalled over fears of unprofitability. The Chinese are also planning a system.

Conceivably a GPS receiver that could use multiple systems would be more accurate. It could also work even when one system or the other was unavailable. Even at the best of times the US system may work intermittently, although it is much better now than previously.

It would be great if the countries working on GPS could develop a universal system. Since that seems unlikely, they should at least cooperate on standards to benefit all users.

For now the systems we have work well in the forest, but every improvement is welcome.

Google vs. Yahoo! Imagery

The image above is a screen capture from an amazing map hack by Sergey Chernyshev that puts Google (left) and Yahoo! maps side by side. To get the above comparison of the Waynesboro Reservoir in the Waynesboro Watershed (where we hold many labs in the Penn State Mont Alto forest technology program) first go to this web address: http://www.sergeychernyshev.com/maps.html . Then enter these search coordinates: 39.818300 -77.455734 (latitude and longitude). Make sure to choose satellite imagery to see just the images or hybrid to see the images and roads.

Both images are high resolution, high quality. Online mapping services tend to have spotty coverage of the best imagery around the US. Google shows a winter scene, where the reservoir is frozen. Yahoo! shows a slightly color enhanced summer scene. The road networks use the same data from Navteq. It' great to be able to see them together side by side.

Online mapping is a trend. It's likely that foresters and other natural resource managers will be using these tools in the future to improve their understanding of the forests and to make field work more efficient. Thanks, Sergey, for this new tool.