Digital Photography Replacing Film - 23/02/2006
In a recent interview on the Australian Broadcasting Corporation (ABC) Science Show, Steve Sasson described his development of the first digital camera thirty years ago, based on small CCD sensors of 100x100 pixels. From those early beginnings it took another twenty to twenty-five years for digital cameras to be developed to the stage where they would have adequate resolution and size to match the quality of film cameras and hence replace them for general photography. Sasson remarked that while film would continue to be used for photography for some niche areas, digital imaging would largely replace film for almost all applications. He also stated his belief that future developments in photography were hard to predict but almost limitless. There were more uses for images, and more images being taken, than ever before.
Competing with Film
The development of digital aerial cameras is following a similar but slower path, but they have advanced significantly over the past four to five years. Worldwide sales are growing rapidly, with a number of companies entering the market. In order for digital aerial cameras to compete with film aerial cameras they need to be able to acquire high-resolution images with similar or better accuracy, have comparable coverage, be suitable for mapping and orthophoto production, and take advantage of the particular characteristics of digital-image acquisition. While the majority of these aims have been largely achieved, the long-term storage of digital information is still an open issue.
Most large-format digital aerial cameras have 12-bit dynamic range for the panchromatic images with ground-pixel sizes as small as 5cm, acquire multi-spectral images, have comparable or better geometric accuracies than film cameras, and record terrabytes of data. Many examples have emerged of practical applications for these cameras. Map production is said to be faster and more economical than with film photogrammetry. Digital aerial photography can cost as little as half that of film-based camera missions and many more images can be taken over a year.
Digital Aerial Future
As with amateur photography, the emergence of the new generation of digital aerial cameras is a consequence of the new technologies that have become available for digital imaging. It has been stated that a ‘paradigm shift’ is occurring in photogrammetric operations due to the availability of highly redundant images that lead to more reliable and accurate information extraction. Multi-spectral images should also lead to more effective automated extraction of thematic information. While aerial film photography will not be completely replaced in the near future, improvements in the quality and capabilities of digital aerial cameras and reductions in costs will occur, leading to greater acceptance by users and a decline in the use of film images. Developments in digital aerial cameras are likely to reflect developments in amateur digital cameras, but with some time lag. The coming decade is likely to bring rapid transformation to digital imaging. Hopefully, increases in the numbers and applications of digital aerial images will also be a consequence of these new developments.