Antarctic Air Photography
Introduction to TMA Air Photos
The PGC now maintains all trimetrogon aerial (TMA) photography* and flight indices of photos taken in the Antarctic from 1946-present. The collection is comprised of more than 330,000 air photos, which were collected and scanned by the USGS EROS Data Center. All image positives were scanned at 400 dots per inch (medium resolution), but resolution varies per image due to differing flightline altitudes. The photos are currently being rescanned at 1000 dots per inch (high resolution) – nearly a 1:1 ratio for digital pixels to the original grain of the film. Photos taken from higher altitude will have a lower resolution and pixels will represent a larger area than photos taken from lower altitudes.
* Trimetrogon photography is a method of taking three photos at one time: one vertical (in this collection, designated by a “V” in the filename), along with left and right obliques (at a 45° angle off nadir; designated by either “L” or “R”) taken along a single TMA flight line. Not all flights were equipped with oblique cameras, and camera malfunctions sometimes limited the availability of a complete set of photos.
PGC has compiled digitized flightline index maps and approximate photo centers in the TMA flightline viewer. The application allows users to browse and download Antarctic air photos digitally rather than having to search through rolls of film in the USGS archives. We even have camera calibration information here for those who need it.
TMA Flightline Viewer
Use the map below or view the full map on PGC's ArcGIS Online portal.
TMA Flightline & Photocenters Raw Data
The PGC provides TMA flightline and photocenters data in two GIS formats:
- ESRI shapefile (.shp)
- Google Earth KMZ files, separated by Antarctic regions:
To view the KMZ files, you'll need Google Earth, a free download.
Looking Up Photos
To look up a photo manually, you will need to understand the naming convention the USGS uses.
- TMA flight line number is identified by the first 4 numbers in the file/folder name, regardless of the letters that precede them (ABCA, ABC, or CA).
- V, R, and L in a file/folder name designate the orientation of the camera used to take the picture: vertical, right, or left.
- The last 4 numbers in the file name of a photo designates the frame number along the flight line.
- The higher-numbered flight lines are typically the most recent.
As an example, if you are looking for TMA flight line 3112, you would begin your search by clicking the folder below labeled "ABCA31". Clicking ABCA31 will then bring you to a set of folders designating all flight lines that begin with "31". The first 4 digits in the name of the folder (e.g., ABCA3112) designates the TMA flight line number. The letter at the end of the folder name will designate vertical (V), right (R) or left (L) photos. The photos themselves are contained within each flight line folder. The 4-digit photo number is appended to the end of the file name (e.g., vertical (V) photo number 0063, [photo number 63] along TMA flight line 3112, has this file name: CA311200V0063).
Thus, if you are looking for vertical photo number 63 along TMA flight line 3112, you would click on ABCA31 below, navigate to the folder titled, "ABCA3112000000V", then navigate to the photo titled, "CA311200V0063.tif".
Please contact Spencer Niebuhr for further details or if you are having difficulty locating the photos.