High Resolution Aerial Photos InformationIf you have used Google Earth, then you know that while the aerial photographs are good for the price (free!), they are often not exceedingly detailed, if there are aerial photographs available at all. Some applications of aerial photography require an exceptional level of detail. When this is the case, only very high resolution aerial photos will be useful, particularly, when the subject matter being examined or illustrated is especially small. An understanding of scale is helpful when comparing vertical aerial photography. Scales are usually expressed either as a ratio of part to part, such as 1:12,000 or a ratio of inches to feet, such as 1"=1000'. Note that both of these scales are, in fact, the same size. In general a film original of relatively recent vintage can withstand a 10x enlargement though sometimes they are enlarged to 20x, which results in a noticeable deterioration in quality. This means that a 1:20,000 scale image can be enlarged to roughly 1"=167' (20,000/12 x 10) at a 10x enlargement. Resolution in digital high resolution aerial photos is usually expressed in a scale of a certain unit of distance represented by one pixel or picture element. An example is a digital aerial product may be rated at a 1' pixel. A one foot pixel resolution will usually be suitable for showing, when printed, no less than 100' feet before the resolution begins to become useless. High resolution aerial photos will be expressed in inches per pixel of resolution. Aerial Archives of San Francisco provides high resolution aerial photos from archives and on assignment. For certain markets, Aerial Archives can provide very high resolution imagery. Some of the highest resolution imagery on a film scale was flown to a scale of 1"=200' or 1:2400, and some of the highest resolution digital photography was flown to a scale of one pixel equals 6" or 3". Aerial Archives will also fly custom aerial photography missions to capture very high resolution aerial photos when this is required for the particular application. These can be either from a vertical angle (straight down) or if more useful, an oblique angle. Aerial Archives serves the Unites States, Canada, and Mexico, but does not currently other service to European countries. Europeans in need of high resolution aerial photos will need to find a European company that offers these services. Good luck with your high resolution aerial photos project, and hopefully this article answered some of your questions. |
