The series consists of aerial photographic print mosaics for reference and map making purposes. The recording agency was responsible for geodesy; and, the medium and small scale topographical mapping of Australia for Commonwealth purposes. Geodesy is the branch of applied mathematics that determines the shape and area of large tracts of country, the exact position of geographical points, and the curvature, shape, and dimensions of the earth. Aerial survey prints (taken at vertical and to scale to minimise distortion), were combined to create print mosaics that provided an aerial overview of the surveyed regions. Photographic prints were laid one on top of the other, matching commonly imaged terrain. The prints were trimmed, with cuts made along a common feature to make edge joins as inconspicuous as possible. Photographs were carefully matched and stuck to a stiff board or plywood base. The print mosaic was annotated with relevant scales (scale in miles, scale for enlargement, etc) and significant features (e.g. rivers, railway lines, townships, etc). This produced a ‘photomap’ that could be used for reference, general planning, and mapping purposes. The mosaic (also known as a lay down) was a tool used to check whether any lateral gaps existed in the photography due to navigation failures during survey flights. The constructed mosaic could be photographed and, if gaps were found, prints of the lay down sent to the operator who produced the aerial survey to be used as reference guide to re-fly the gaps. This system allowed for more accurate identification of gaps in the photography and minimised the amount of flights required to obtain complete coverage. Other possible uses of print mosaics include: as a visual record of aerial survey projects, as an index of available photographs, as a reference to terrain e.g. borders, land cover, land use, planning or engineering projects, etc. Each item contains some or all of the follow: location, approximate scale in miles, approximate degree, scale for enlargement, date of creation, date of photography, name of agent that undertook the aerial survey (e.g. RAAF), and significant features. In mapping, ratios or representative fractions (RFs) are used to indicate how many units on the earth's surface are equal to one unit on the image. Prior to 1956 Australia used the British map scale series (based on the Imperial measurement system), where map units, depending on the scale, were measured in inches and miles e.g. one inch on the image was equivalent to four miles on the ground. The series was discontinued when the agency moved to the use of photographic negatives for photogrammetric restitution for map making purposes. Sources Series documentation Geoscience Australia, ‘Our History’, downloaded 5 May 2009 from http://www.ga.gov.au/about-us/history.jsp Geoscience Australia, ‘Aerial Photography’, downloaded 5 May 2009 from http://www.ga.gov.au/remote-sensing/aerial-photography/ Arctic Institute of North America's publications server, ‘Photographic Operations of the Royal Canadian Air force’, downloaded 29 June 2009 from http://pubs.aina.ucalgary.ca/arctic/Arctic3-3-150.pdf U. S. Army Corps of Engineers Staff, American Society of Civil Engineers, ‘Photogrammetric mapping’, downloaded 25 June 2009 from http://books.google.com.au/books Archivist notes The original series notes included two ‘unregistered links notes’ see below. The CRS manual (section 7.6.2) advises that unregistered notes links are no longer used. In accordance with the CRS the notes were removed and data place in the series notes or descriptive note.

Related series unregistered

International Index of Australia (Grid Map) Grid Index Cards to International Index of Australia

Subsequent series unregistered

Stuck-up mosaics are now discontinued - the Department now uses photographic negatives