History of Cartography

Historical Topographic Maps

4109.3 - Assessing a potential solution for spatially referencing of historical aerial photography in South Africa

Tuesday, July 4
9:10 AM - 9:30 AM
Location: Harding

Assessing a potential solution for spatially referencing of historical aerial photography in South Africa

Michele Denner,1 Jacobus H. Raubenheimer,2

1. Department of Rural Development and Land Reform, Chief Directorate: National Geospatial Information, Mowbray, Western Cape, South Africa; michelle.denner@drdlr.gov.za,
2. Cape Peninsula University of Technology, Bellville, Western Cape, South Africa; RaubenheimerJ@cput.ac.za

1. Introduction

Historical aerial photography is a valuable resource for any country as it provides an exact visual record of land use at a specific moment in time. South Africa is a country plagued by various discriminatory past practises of land administration, and thus, the availability of historical data will give context to previous land administration and become a fundamental aid in addressing past injustices. The national mapping organisation has a vast repository of such historical analogue aerial photography, dating back to the early 1900’s. In order to effectively utilise these datasets in a digital environment requires that it be georeferenced to an accuracy that suits the purpose for which it is to be used.

2. Research methodology

This research sought to explore the accuracies achievable, against the national standard for ortho-rectification of historical aerial photography in South Africa given the type of scanning equipment and epoch range between the historical photography and the reference image. The research involved using the currently available methods of scanning historical aerial photography and a technique of image-to-image georeferencing.

The research was delineated to historical aerial photography flown at a nominal scale of 1:30 000. The study site comprised of a largely developed area of approximately 25 kilometres long by 15 kilometres wide. It comprised of mixed land uses such as urban, farming, recreational, nature reserves, retail and various types of transport. The epoch range of the historical aerial photography ranged over a period of sixty years, from 1953 to 2014. The research was conducted by doing four tests using aerial photography from different time epochs over the sixty year period. The process of ortho-rectification through image-to-image alignment matched each test to an existing ortho-rectified mosaic from 2014 epoch of the test area. Digital elevation models were included into the processing. The historical aerial photography was scanned using two different types of scanning equipment.

3. Results

Each epoch of photography was ortho-rectified using the PCI Geomatics Ortho-Engine software with the Historical Aerial Photography (HAP) functionality. Each set of results was assessed in terms of visual accuracy of any apparent shifts in the mosaiced epochs, spatial accuracy utilising both the cadastral overlay and random geographically distributed points over the study site. The results showed a decrease in the overall accuracy of the image as the time range between the reference image and the historical aerial photography epoch increased. Results were also affected by the type of scanning equipment used to scan the historical aerial photography. The paper will show the different accuracies obtained and the applications possible with the different epochs.

4. Recommendation

Only photography scanned with a high resolution photogrammetric scanner produced an ortho-rectified image that conformed to the national standard. It was recommended that a “second order orthophoto” product be developed that could provide a historical perspective to disciplines such as change detection and the identification of land use as an aid to addressing past injustices of land administration in South Africa.


Michele Denner

Senior Geomatics Manager
Department of Rural Development and Land Reform, South Africa

Michele Denner is employed within the Department of Rural Development and Land Reform, South Africa, based at the Chief Directorate: National Geospatial Information. She holds a Masters in Business Administration, a Higher National Diploma in Surveying and has recently completed her BTech Degree in Surveying. She has managed the national aerial photography program for over 20 years and was involved in the implementation of the migration from analogue aerial photography to digital imagery.

Presentation(s):

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Elri C. Liebenberg

Professor
University of South Africa

Elri Liebenberg was Professor and Head of the Department of Geography and Environmental Studies of the University of South Africa. She has published widely on the history of cartography of Southern Africa, is the Regional Editor of the Cartographic Journal for Africa and an Assistant-Editor for the ICA International Journal of Cartography . She has been a member of the South African National Committee for the ICA since 1987, was a Vice-President of the ICA from 1999 to 2003, and was Chairperson of the ICA Commission on the History of Cartography from 2007 until 2015.



Presentation(s):

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