Comments:
Two separate records of flight navigation were collected during the survey.
The first was a continuous ASCII text file from the PLGR that recorded only latitudes and longitudes for the entire flight at 30-sec intervals. No time values were recorded by the PLGR. The second navigation record was recorded in the subtitles of the video footage that was shot continuously during the survey. The video subtitles recorded latitude, longitude, and time in hours, minutes, and seconds. In order to produce a digital record of the navigation that included time, the latitude, longitude, and time were manually extracted from the video every 5 min and these values were matched to the latitude and longitude in the PLGR file. Then the time was interpolated between these 5-min fixes using Excel to produce a 1-sec time value record for the entire flight.
A Nikon MF-14 data back marks the time each photograph was acquired on the lower right corner of the image in day, hour, and minute format. These values were entered from the photographs into an Excel spreadsheet. It is assumed for the purposes of locating the images that the photographs were taken at a constant rate during any given minute of flight. To assign a time value in seconds to each photograph, the number of photographs taken during each minute was evenly distributed across that minute. For example, if 15 photographs were taken during minute 19:00:00, we assume that a picture was taken every 4 sec. The photographs are assigned the time values 19:00:00, 19:00:04, 19:00:08, and so on. As a result, it should be noted that the positions assigned to each photograph are an estimate of the aircraft position, not the location of the landmark photographed.
The time values were then cross-referenced to the interpreted latitude and longitude values discussed above to assign positions to each photograph.
