Historical aerial photographs and digital photogrammetry for

249 Pages·2016·9.79 MB·English

Loughborough University
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Historical aerial photographs
and digital photogrammetry
for landslide assessment
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• Submitted in partial ful(cid:28)lment of the requirements for the award of the
degree of Doctor of Philosophy of Loughborough University.
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Historical Aerial Photographs and
Digital Photogrammetry for
Landslide Assessment

by
Jan Walstra

A Doctoral Thesis
Submitted in partial fulfilment of the requirements
for the award of
Doctor of Philosophy of Loughborough University

November 2006

© Jan Walstra 2006
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Key words: Digital photogrammetry, Historical aerial photographs, Landslide
monitoring, Landform change, Digital Elevation Model (DEM), Orthophoto,
Displacement vector, Data quality.

This study demonstrates the value of historical aerial photographs as a source for
monitoring long-term landslide evolution, which can be unlocked by using appropriate
photogrammetric methods.
The understanding of landslide mechanisms requires extensive data records; a
literature review identified quantitative data on surface movements as a key element
for their analysis. It is generally acknowledged that, owing to the flexibility and high
degree of automation of modern digital photogrammetric techniques, it is possible to
derive detailed quantitative data from aerial photographs. In spite of the relative ease
of such techniques, there is only scarce research available on data quality that can be
achieved using commonly available material, hence the motivation of this study.
In two landslide case-studies (the Mam Tor and East Pentwyn landslides) the
different types of products were explored, that can be derived from historical aerial
photographs. These products comprised geomorphological maps, automatically
derived elevation models (DEMs) and displacement vectors. They proved to be useful
and sufficiently accurate for monitoring landslide evolution. Comparison with
independent survey data showed good consistency, hence validating the techniques
used.
A wide range of imagery was used in terms of quality, media and format.
Analysis of the combined datasets resulted in improvements to the stochastic model
and establishment of a relationship between image ground resolution and data
accuracy. Undetected systematic effects provided a limiting constraint to the accuracy
of the derived data, but the datasets proved insufficient to quantify each factor
individually.
An important advancement in digital photogrammetry is image matching,
which allows automation of various stages of the working chain. However, it appeared
that the radiometric quality of historical images may not always assure good results,
both for extracting DEMs and vectors using automatic methods.
It can be concluded that the photographic archive can provide invaluable data
for landslide studies, when modern photogrammetric techniques are being used. As
ever, independent and appropriate checks should always be included in any
photogrammetric design.
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This thesis is the reward of three years of research at Loughborough University.
Although I have enjoyed these years very much, completion would not have been
possible without the support of so many people.
First of all, I am very grateful to my supervisors, Jim Chandler and Neil
Dixon, for their endless patience, constant encouragement and valuable advice
throughout my research. Also, I would like to thank Tom Dijkstra for sharing some
of his enthusiasm about landslides. I also appreciated the help by Alan Forster,
Kevin Northmore (both of BGS) and Howard Siddle (Halcrow), who provided me
with useful advice and reports on the landslides in South Wales. Special thanks go
to ‘ze dzjermans’, Uli and René (in chronological order), not only for their company
in and outside the office, but especially for resisting the ‘lovely’ British weather
during the field surveys. For the latter I also owe thanks to Patricia, although she
actually enjoyed it.
However, my time in Loughborough would have never been quite so
enjoyable without the special crews from ‘residence 114’ and ‘Middleton Place’ (no
need for names) – and the many, many great friends from every corner of the
world that I met in this little town (too many names). Sometimes I cannot help
wondering if I should say ‘in spite of’ them I managed to accomplish this work.
Anyway, thanks for the unforgettable time!
My final thanks are to my parents; without their undisputable support and
consideration I would not have got this far.

Loughborough, May/November 2006
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Abstract......................................................................................................ii
Acknowledgements ...................................................................................iii
Contents....................................................................................................iv
List of figures ............................................................................................ix
List of tables............................................................................................ xvi
1 Introduction.........................................................................................1
1.1 Background.....................................................................................1
1.2 Aim and objectives...........................................................................2
1.3 Contribution to knowledge.................................................................3
1.4 Structure of thesis............................................................................3
2 Landslides............................................................................................5
2.1 Definitions and terminology...............................................................5
2.2 Landslide classification......................................................................6
2.3 Landslide mechanisms.....................................................................12
2.3.1 Failure.....................................................................................12
2.3.1.1 Material............................................................................13
2.3.1.2 Geology............................................................................13
2.3.1.3 Water...............................................................................13
2.3.1.4 Vegetation........................................................................15
2.3.1.5 Time ................................................................................16
2.3.2 Movement ...............................................................................16
iv
Contents v
2.3.2.1 Translational slides.............................................................17
2.3.2.2 Rotational slides ................................................................17
2.3.2.3 Mudslides..........................................................................18
2.4 Aerial photographs in landslide studies...............................................19
2.4.1 Aerial Photograph Interpretation (API) ........................................20
2.4.1.1 Photographic parameters....................................................21
2.4.1.2 Natural factors...................................................................23
2.4.1.3 Experience of the interpreter & analysis techniques................23
2.4.2 Geomorphological mapping........................................................24
2.4.3 Recognition of landslides...........................................................26
2.4.4 Monitoring of landslides.............................................................27
2.4.5 Landslide hazard mapping .........................................................32
2.5 Summary.......................................................................................35
3 Digital photogrammetric techniques..................................................36
3.1 Development of photogrammetry......................................................36
3.2 Analytical restitution........................................................................38
3.2.1 The collinearity condition...........................................................38
3.2.1.1 Interior orientation.............................................................38
3.2.1.2 Exterior orientation............................................................40
3.2.1.3 Collinearity equations.........................................................40
3.2.2 Photogrammetric solutions.........................................................42
3.2.3 Stochastic models.....................................................................44
3.3 Image matching..............................................................................44
3.3.1 Cross-correlation matching........................................................45
3.3.2 Least-squares matching ............................................................46
3.4 Automated DEM extraction...............................................................47
3.5 Orthophoto generation.....................................................................48
3.6 Data quality – controls and evaluation...............................................49
3.6.1 Precision..................................................................................49
3.6.2 Accuracy .................................................................................51
3.6.3 Reliability ................................................................................52
3.7 Review of photogrammetry in landform change studies........................53
3.7.1 API-based monitoring................................................................53
3.7.2 DEM methods...........................................................................54
3.7.3 Displacement vectors................................................................55
Contents vi
3.8 Summary.......................................................................................58
4 Methodology......................................................................................62
4.1 Selection of field sites......................................................................62
4.2 Extracting morphological data from images........................................65
4.2.1 Acquiring photographs ..............................................................65
4.2.1.1 National Monuments Record (NMR)......................................65
4.2.1.2 Central Register of Air Photography for Wales (CRAPW)..........66
4.2.1.3 Cambridge Univ. Collection of Aerial Photographs (CUCAP)......66
4.2.1.4 Ordnance Survey (OS)........................................................66
4.2.1.5 Agricultural Development and Advisory Service (ADAS)..........66
4.2.1.6 Local authorities................................................................66
4.2.1.7 Commercial sector.............................................................67
4.2.2 Collecting ground control...........................................................68
4.2.3 Photogrammetric processing......................................................72
4.2.3.1 Restitution........................................................................72
4.2.3.2 DEM extraction..................................................................73
4.2.3.3 Orthophoto generation .......................................................74
4.2.4 Data quality assessment............................................................74
4.3 Quantify and visualise landslide dynamics..........................................75
4.3.1 Geomorphological maps............................................................76
4.3.2 ‘DEMs of difference’ ..................................................................76
4.3.3 Displacement vectors................................................................78
4.3.4 Animations ..............................................................................81
4.4 Use data for landslide mechanisms....................................................81
4.4.1 Landslide mechanisms...............................................................81
4.4.2 Compare with other work ..........................................................83
4.5 Summary.......................................................................................84
5 Case study Mam Tor...........................................................................85
5.1 Site description...............................................................................85
5.1.1 Geology...................................................................................86
5.1.2 Morphology..............................................................................87
5.1.3 Movement history.....................................................................89
5.1.4 Correlation with rainfall data......................................................92
5.2 Acquired photographs......................................................................93
5.3 Ground control collection..................................................................95
Contents vii
5.4 Photogrammetric processing.............................................................97
5.4.1 Restitution...............................................................................97
5.4.2 DEM extraction.......................................................................114
5.4.3 DEM quality...........................................................................114
5.4.4 Orthophoto generation............................................................119
5.5 Visualisation and analysis...............................................................119
5.5.1 Geomorphological map............................................................119
5.5.2 ‘DEMs of difference’ ................................................................121
5.5.3 Displacement vectors..............................................................127
5.5.4 Comparing with ground survey data..........................................133
5.5.5 Animations ............................................................................135
5.6 Landslide mechanisms...................................................................135
5.7 Summary.....................................................................................138
6 Case study East Pentwyn.................................................................139
6.1 Study area ...................................................................................139
6.1.1 Geology.................................................................................140
6.1.2 Morphology............................................................................141
6.1.3 Movement history...................................................................143
6.2 Acquired photographs....................................................................145
6.3 Ground control collection................................................................146
6.4 Photogrammetric processing...........................................................148
6.4.1 Restitution.............................................................................148
6.4.2 DEM extraction.......................................................................158
6.4.3 DEM Quality...........................................................................159
6.4.4 Orthophoto generation............................................................159
6.5 Visualisation and analysis...............................................................161
6.5.1 Geomorphological maps..........................................................161
6.5.2 ‘DEMs of difference’ ................................................................163
6.5.3 Displacement vectors..............................................................164
6.5.4 Comparing with ground survey data..........................................167
6.6 Summary.....................................................................................169
7 Discussion........................................................................................171
7.1 Restitution....................................................................................171
7.2 DEMs...........................................................................................181
7.3 Orthophotographs.........................................................................184
Contents viii
7.4 Displacement vectors.....................................................................187
7.5 Obliques.......................................................................................190
7.6 Implications for landslide studies.....................................................192
7.7 Summary.....................................................................................193
8 Conclusion .......................................................................................196
8.1 Literature review...........................................................................196
8.2 Case-studies.................................................................................197
8.3 Data quality issues........................................................................197
8.4 Relevance to landslide studies.........................................................198
8.5 Recommendations.........................................................................199
References..............................................................................................200
Appendix 1 – Publications ......................................................................216
Appendix 2 – Sources for aerial photographs.........................................217
Appendix 3 – Matlab scripts....................................................................220