OUR INDUSTRIAL LEGACY WHAT ARE WE LEAVING OUR CHILDREN REAAA Roadshow Taupo, August 2016 Young presenter s competition

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1 OUR INDUSTRIAL LEGACY WHAT ARE WE LEAVING OUR CHILDREN Preserving the country s aerial photography archive for future generations Abstract For over eighty years, aerial photography has captured the changing landscape and developing infrastructure across New Zealand. With the use of technology, Opus International Consultants Ltd in partnership with Land Information New Zealand is preserving the country s aerial photography archive for future generations. This paper covers the history of the archive, the author s involvement in managing the preservation of this valuable resource. It also highlights the opportunities available to roading engineers throughout the country to advance infrastructure management now and into the future. Author: Stephanie Orbell Company: Opus International Consultants Ltd Napier stephanie.orbell@opus.co.nz

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3 Introduction New Zealand has been photographed from the air since This photography has captured changing landscape and developing infrastructure including the roads that transport our people and goods between communities. New Zealand's largest and most comprehensive aerial photography archive is housed at Opus international Consultants (Opus), Napier. Eighty years of New Zealand history on large format film sit inside a vault and scanning room, purpose built in 2014 to store and reproduce products from the massive collection of historic aerial surveys. With the use of technology, Opus and Land Information New Zealand (LINZ) are preserving the country s aerial photographic archive for future generations. Archive History New Zealand's growth in infrastructure is well documented within the archive, including roads, dams, power projects and forestry during the 1950s and early 1960s. One example is the capture of all of NZ highways. By 1962 all of the North Island and two-thirds of the South Island had aerial photographic coverage. An aerial survey of Christchurch was of assistance to the Police security plan for the 1974 Royal visit to the Commonwealth Games in Christchurch also saw thermovision imagery captured over Taupo and Rotorua recording 2 degree ground temperature variations to locate geothermal hotspots assisting with road realignment projects. Fig1. Flight Charts: SH52 survey 1960, Rotorua thermovision survey

4 Archive Preservation The archive consists of over 745,000 images. Its preservation, estimated to take approximately ten years to complete, will result in historic aerial surveys being available digitally for future generations. One of our biggest challenges is ensuring correct handling and storage of the archive. Temperature and humidity are constantly being monitored and controlled. The Vault has been purpose built in accordance with Archives NZ Standards. Fig2. Large format film Scanners, advantage of a photogrammetric scan To digitise the historical aerial photography archive, we use large format film photogrammetric scanners. These scanners capture the image with 12 bit sensors working in a boustrophedonic path. Our scanners are quite different to a normal flatbed scanner, which are designed for high radiometric reproduction only i.e. colour, tone, etc. Photogrammetric scanners are designed for high radiometric and geometric accuracy. The high geometrically accurate images that are produced can then be used to create geometrically corrected products such as mosaic orthophotos. These are adjusted to match the surface of the earth and are a valuable resource for engineers, planners, surveyors, etc. to measure between points or features. They need to show interpretable details for ground control measurement and this is why the tonal balance of every individual scan is also carefully managed as part of our scanning process. Our scanners are calibrated monthly and immediately following an earthquake to ensure absolute accuracy. Fig3. Large format Photogrammetric Scanner 4

5 Opportunities available to roading engineers to advance infrastructure management now and into the future Scanned aerial photos are a great visual, but are unable to be used for measuring distances. This is because of distortions caused by the curvature of the earth, the angle of the camera and the topography of the land especially on rugged terrain, common in New Zealand. A geometrically corrected (orthorectified) survey, is adjusted to accurately represent the earth s surface, identical to a map. Created by georeferencing aerial photos, orthophotos can be easily loaded as a layer into GIS software applications where property boundary s and roading plans for example can be overlaid and referenced. This is a valuable resource, combining the visual information of a photograph with the detail of map data, allowing a user to determine exact locations of features and to measure distances accurately. Orthophotos are just one example of many modern GIS products that can be made from historic aerial surveys, particularly useful for large-scale engineering projects and urban planning. Fig4. Raw (unrectified) scanned image, Orthorectified image Today, digital technology allows the landscape to be captured, modelled and analysed quickly and inexpensively. Various outputs such as 3D point clouds, digital surface models, videos, contour models and mosaic orthophotos have a wide range of uses. Recent capture can be easily compared to a historical product (e.g. Orthophoto) of the same site to visualise and report land changes and/or uses over time. Technology is assisting us make this historical reference material readily accessible and easier than ever for you to use today and for future generations. It s important this resource is available to anyone who may need to utilise it. Opus take pride in administering the archive and providing the historic aerial surveys in multiple formats considerably more usable than scanned images alone. At completion of the project our children will be left with a valuable infrastructure management resource. 5

6 Opus International Consultants Ltd Opus House, 6 Ossian Street Private Bag 6019, Hawkes Bay Mail Centre, Napier 4142 New Zealand t: f: w: 6