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Heritage in Three-Dimensions
Heritage in Three-Dimensions
Heritage in Three-Dimensions
Heritage in Three-Dimensions
Heritage in Three-Dimensions
Heritage in Three-Dimensions
Heritage in Three-Dimensions
Heritage in Three-Dimensions
Heritage in Three-Dimensions
Heritage in Three-Dimensions
Heritage in Three-Dimensions
Heritage in Three-Dimensions
Heritage in Three-Dimensions
Heritage in Three-Dimensions
Heritage in Three-Dimensions
Heritage in Three-Dimensions
Heritage in Three-Dimensions
Heritage in Three-Dimensions
Heritage in Three-Dimensions
Heritage in Three-Dimensions
Heritage in Three-Dimensions
Heritage in Three-Dimensions
Heritage in Three-Dimensions
Heritage in Three-Dimensions
Heritage in Three-Dimensions
Heritage in Three-Dimensions
Heritage in Three-Dimensions
Heritage in Three-Dimensions
Heritage in Three-Dimensions
Heritage in Three-Dimensions
Heritage in Three-Dimensions
Heritage in Three-Dimensions
Heritage in Three-Dimensions
Heritage in Three-Dimensions
Heritage in Three-Dimensions
Heritage in Three-Dimensions
Heritage in Three-Dimensions
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Heritage in Three-Dimensions

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Presentation given at the Computer Applications in Archaeology UK Chapter Meeting, April 2011, held at the University of Birmingham. …

Presentation given at the Computer Applications in Archaeology UK Chapter Meeting, April 2011, held at the University of Birmingham.

The subject is the use of terrestrial and airborne laser scanners in heritage contexts.

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  • 1. Heritage in three-dimensions Terrestrial and Airborne Laser Scanning in heritage contexts <ul><li>Paul Cripps </li></ul><ul><li>Geomatics Manager, Wessex Archaeology </li></ul>
  • 2. Overview <ul><li>Why? </li></ul><ul><ul><li>Why do we use laser-scanners? </li></ul></ul><ul><ul><li>What are the benefits/problems? </li></ul></ul><ul><li>How? </li></ul><ul><ul><li>How do we use the tools available? </li></ul></ul><ul><ul><li>Advantages/disadvantages </li></ul></ul><ul><ul><li>Workflows </li></ul></ul><ul><li>Case studies </li></ul>
  • 3. An additional recording tool <ul><li>Terrestrial Laser Scanners (TLS), Close Range Laser Scanners &amp; Airborne Laser Scanners (ALS) provide additional survey/recording tools </li></ul><ul><ul><li>Not universal panacea </li></ul></ul><ul><ul><li>Ideal for capturing large amounts of 3D surface measurements </li></ul></ul><ul><ul><li>Part of an armoury which includes traditional measured drawing, photogrammetry, (rectified) photography, TST, GPS and laser scanners </li></ul></ul><ul><li>Complementary not replacement </li></ul><ul><ul><li>Typically used as part of an overall survey methodology </li></ul></ul><ul><ul><li>Typically used in conjunction with other equipment/techniques/methods </li></ul></ul>
  • 4. Right tools for the job <ul><li>Laser scanners record points across surfaces (ie indirect survey technique) </li></ul><ul><ul><li>cf traditional recording of points, lines and edges using TST/GNSS (ie direct survey technique) </li></ul></ul><ul><ul><li>Surface recording ideally suited to many heritage applications </li></ul></ul><ul><ul><li>eg buildings, earthworks, landscapes, objects </li></ul></ul><ul><li>Laser scanners are very fast </li></ul><ul><ul><li>Large volumes of high precision data captured </li></ul></ul><ul><ul><li>High speed data capture </li></ul></ul><ul><ul><li>Shorter fieldwork duration </li></ul></ul><ul><li>Variety of scanners suited to different purposes </li></ul><ul><li>Again, not universally applicable </li></ul>
  • 5. Practicalities (TLS) <ul><li>Costs of ownership </li></ul><ul><ul><li>Expensive hardware and software </li></ul></ul><ul><ul><li>Hire vs purchase </li></ul></ul><ul><ul><li>Partnerships </li></ul></ul><ul><li>Skills </li></ul><ul><ul><li>Survey design; how to structure a survey </li></ul></ul><ul><ul><li>Field survey; how to undertake a survey </li></ul></ul><ul><ul><li>Data processing; how to prepare &amp; handle the data </li></ul></ul><ul><ul><li>Visualisation, Analysis &amp; Interpretation; working with &amp; producing outputs from the data </li></ul></ul><ul><li>Data </li></ul><ul><ul><li>Massive datasets </li></ul></ul>
  • 6. Practicalities (ALS) <ul><li>Costs of data </li></ul><ul><ul><li>Relatively inexpensive to purchase off the shelf </li></ul></ul><ul><ul><li>Expensive to capture new data </li></ul></ul><ul><li>Skills </li></ul><ul><ul><li>Data processing; how to prepare &amp; handle the data </li></ul></ul><ul><ul><li>Visualisation, Analysis &amp; Interpretation; working with &amp; producing outputs from the data </li></ul></ul><ul><ul><li>Using the data as 3D data vs static imagery </li></ul></ul><ul><li>Data </li></ul><ul><ul><li>Massive datasets </li></ul></ul>
  • 7. Workflow (TLS) <ul><li>Careful survey design required </li></ul><ul><ul><li>Placement of scan stations </li></ul></ul><ul><ul><li>Shadows &amp; obstructions </li></ul></ul><ul><li>Field survey </li></ul><ul><ul><li>Reduced time vs TST/GNSS </li></ul></ul><ul><li>Post-fieldwork </li></ul><ul><ul><li>Takes the time! </li></ul></ul><ul><ul><li>Processing </li></ul></ul><ul><ul><ul><li>Registration </li></ul></ul></ul><ul><ul><ul><li>Decimation </li></ul></ul></ul><ul><ul><li>Analysis </li></ul></ul><ul><ul><ul><li>GIS or CAD </li></ul></ul></ul>
  • 8. Workflow (TLS) <ul><li>Different approach from direct survey techniques </li></ul><ul><li>Captures data regardless of product or purpose </li></ul><ul><ul><li>Determined by machine used and settings applied </li></ul></ul><ul><ul><li>Can of course be optimised for case in hand (survey design) </li></ul></ul><ul><li>Often no need for repeat surveys to produce alternative products </li></ul><ul><ul><li>reusable data </li></ul></ul><ul><li>Reduced time in the field vs increased time in the office </li></ul><ul><ul><li>Overall reduction in time…? </li></ul></ul>
  • 9. Workflow (TLS) <ul><li>Choice of survey points becomes office based </li></ul><ul><ul><li>Select/digitise/draw from point cloud </li></ul></ul><ul><ul><li>cf TST/GNSS choice of points field based </li></ul></ul><ul><li>Better access to supporting resources </li></ul><ul><ul><li>Historic drawings, photographs, plans </li></ul></ul><ul><ul><li>Documentation </li></ul></ul><ul><ul><li>Colleagues &amp; external specialists </li></ul></ul><ul><li>Visualisation tools </li></ul><ul><li>Indoors, more time to think in relative comfort! </li></ul>
  • 10. Products and outputs (TLS) <ul><li>Same old vs new and shiny </li></ul><ul><ul><li>Not necessarily the right course to produce same old </li></ul></ul><ul><ul><li>eg ortho-images vs drawn elevations </li></ul></ul><ul><li>Point cloud capable of supporting range of outputs </li></ul><ul><ul><li>Contour plots </li></ul></ul><ul><ul><li>CAD drawings and extracted vectors, including elevation drawings, at any scale </li></ul></ul><ul><ul><li>Solid modelling and fitting of primitives </li></ul></ul><ul><ul><li>Wireframe models </li></ul></ul><ul><ul><li>Digital Surface Models (DSMs) suitable for use in GIS </li></ul></ul><ul><li>Archival datasets </li></ul><ul><ul><li>ASCII text </li></ul></ul><ul><ul><li>Big Data! </li></ul></ul>
  • 11. Workflow, products and outputs (ALS) <ul><li>Acquire data </li></ul><ul><ul><li>Purchase or commission </li></ul></ul><ul><li>Process data </li></ul><ul><ul><li>DSM, DTM, derived products </li></ul></ul><ul><li>Workflow: </li></ul><ul><ul><li>Interpret and transcribe interpretations as needed </li></ul></ul><ul><ul><li>Visualisations + spatial analysis to assist interpretation </li></ul></ul><ul><li>Products &amp; Outputs: </li></ul><ul><ul><li>Maps &amp; plans </li></ul></ul><ul><ul><li>GIS data </li></ul></ul><ul><ul><li>Similar but different </li></ul></ul><ul><ul><ul><li>Larger scale possible vs eg GNSS/TST/TLS </li></ul></ul></ul><ul><ul><ul><li>Lower resolution &amp; precision vs eg GNSS/TST/TLS </li></ul></ul></ul>
  • 12. Archaeology is the key! <ul><li>Many survey companies now operate in this field </li></ul><ul><ul><li>Most technically competent; RICS, TSA </li></ul></ul><ul><li>Architectural drawings vs archaeological drawings </li></ul><ul><ul><li>Very different focus </li></ul></ul><ul><ul><li>Level of detail </li></ul></ul><ul><ul><li>Interpretation </li></ul></ul><ul><li>Topographic survey vs Archaeological topographic survey </li></ul><ul><ul><li>Different emphasis </li></ul></ul><ul><ul><li>Interpretation </li></ul></ul><ul><li>Fitness for purpose; Appropriate use of techniques depends on </li></ul><ul><ul><li>Understanding of technology </li></ul></ul><ul><ul><li>Understanding of archaeology </li></ul></ul>
  • 13. Developments <ul><li>Technology advances apace </li></ul><ul><li>Computer hardware </li></ul><ul><ul><li>More capable of working with more data </li></ul></ul><ul><ul><li>64-bit OS, SSDs, 12Gb RAM, etc </li></ul></ul><ul><li>Software </li></ul><ul><ul><li>Better, improved tools for working with data </li></ul></ul><ul><ul><li>Pointools, PointCloud, PhoToPlan, Cyclone, Cloudworx, ArcGIS, meshlab, etc </li></ul></ul><ul><li>Scanners </li></ul><ul><ul><li>Latest generation phase scanners down to sub-millimetre (ish), smaller, battery powered </li></ul></ul><ul><ul><li>Colour capture via onboard cameras (or external DSLR) </li></ul></ul>
  • 14. Developments <ul><li>Exciting stuff! </li></ul><ul><li>Integration of photography &amp; scan data </li></ul><ul><ul><li>Register photo(s) to point cloud </li></ul></ul><ul><ul><li>Draw onto photos, vector snaps to point cloud </li></ul></ul><ul><ul><li>Draw same line on two photos, 3D vector </li></ul></ul><ul><li>Like photogrammetry but with any photographs or other imagery </li></ul><ul><ul><li>Uncontrolled, historic, aerial, etc </li></ul></ul><ul><ul><li>Maps, plans, etc </li></ul></ul>
  • 15. Developments <ul><li>Reflectance Transformance Imaging (RTI) and Polynomial Texture Mapping (PTM) </li></ul><ul><ul><li>Image based technique for looking at surfaces </li></ul></ul><ul><ul><li>Works with virtual surfaces too </li></ul></ul><ul><ul><li>eg Laser scan data including close range, ALS and TLS </li></ul></ul><ul><li>Potential for integration within GIS </li></ul><ul><ul><li>Bit like super interactive hillshades </li></ul></ul>
  • 16. Developments
  • 17. Developments <ul><li>Lidar techniques </li></ul><ul><ul><li>Working with LiDAR over and above basic image based techniques </li></ul></ul><ul><ul><li>Statistical approaches to display enhancement </li></ul></ul><ul><ul><li>Lighting models &amp; PTM </li></ul></ul><ul><ul><li>‘ Normalisation’ </li></ul></ul><ul><li>Composite views </li></ul><ul><ul><li>Multivariate: CASI, LiDAR elevation, LiDAR intensity, geophysics, etc </li></ul></ul>
  • 18. Case studies
  • 19. Orcheston church <ul><li>Evaluation of technology back in 2001 </li></ul><ul><li>Tested range of outputs and automated extraction of vectors &amp; surfaces </li></ul>Point cloud Vector model Surface model
  • 20. Tamworth Castle <ul><li>Existing laser scan dataset </li></ul><ul><ul><li>1.4 billion measurements </li></ul></ul><ul><ul><li>Phase, no colour </li></ul></ul><ul><li>New photographic survey </li></ul><ul><ul><li>Ground &amp; aerial </li></ul></ul><ul><li>Combined to produce stone by stone elevation drawings </li></ul><ul><ul><li>3D wireframe  2D drawings </li></ul></ul><ul><li>No need for resurvey </li></ul><ul><ul><li>Cost effective </li></ul></ul><ul><li>High quality product </li></ul><ul><ul><li>Prepared to EH Metric Survey specifications </li></ul></ul>
  • 21. Tamworth Castle
  • 22. Tamworth Castle
  • 23. Sandsfoot Castle <ul><li>Requirements: </li></ul><ul><ul><li>topographic survey of interior &amp; immediate environs including earthworks </li></ul></ul><ul><ul><li>Stone by stone elevation drawings as record </li></ul></ul><ul><ul><li>Panoramic photography </li></ul></ul><ul><li>TLS  CAD+GIS </li></ul><ul><ul><li>Drawn elevations </li></ul></ul><ul><ul><li>DSM &amp; contours </li></ul></ul>
  • 24. Sandsfoot Castle <ul><li>Products: </li></ul><ul><ul><li>Elevation drawings </li></ul></ul><ul><ul><li>Orthographic images </li></ul></ul>
  • 25. Sandsfoot Castle
  • 26. Wakehurst Place <ul><li>National Trust property </li></ul><ul><li>Complex external elevations </li></ul><ul><li>Drawn elevations, floor plans, etc </li></ul><ul><ul><li>Traditional products </li></ul></ul><ul><li>Combination approach </li></ul><ul><ul><li>Direct &amp; Indirect survey techniques + image based methods </li></ul></ul><ul><li>Survey control network </li></ul><ul><ul><li>Closed loop traverse </li></ul></ul><ul><li>Located using GNSS </li></ul><ul><ul><li>OS map a little out… </li></ul></ul>
  • 27. Wakehurst Place
  • 28. Salisbury Plain <ul><li>Monitoring of earthworks </li></ul><ul><ul><li>Topographic survey using TLS </li></ul></ul><ul><li>Restricted access </li></ul><ul><ul><li>Short fieldwork duration required </li></ul></ul><ul><ul><li>Weeks for GNSS vs days for TLS </li></ul></ul><ul><li>GIS based analysis </li></ul><ul><ul><li>DSMs </li></ul></ul><ul><ul><li>Derived products; slope </li></ul></ul><ul><ul><li>Models of change </li></ul></ul>
  • 29. Hillfort <ul><li>Topographic survey of earthworks </li></ul><ul><li>Combination approach: Laser scanner + GPS </li></ul>
  • 30. South Wales <ul><li>19 airborne LiDAR datasets </li></ul><ul><li>40km 2 </li></ul><ul><li>133.5 million data points </li></ul><ul><li>2 surface models </li></ul><ul><ul><li>Unfiltered elevation </li></ul></ul><ul><ul><li>Intensity </li></ul></ul><ul><li>Hillshades, histogram enhancement, slope </li></ul><ul><li>Transcription of hillshaded views </li></ul>Elevation component Intensity component
  • 31. Garrison complex <ul><li>Record garrison in advance of redevelopment </li></ul><ul><li>Visualisation of existing buildings and their context </li></ul><ul><li>Used to target further recording works </li></ul><ul><ul><li>Direct Survey using TST </li></ul></ul><ul><li>0.75 km 2 surveyed </li></ul><ul><li>37 buildings </li></ul><ul><li>25 billion measurements </li></ul><ul><li>18Gb data file </li></ul><ul><li>10-25mm effective resolution </li></ul>
  • 32. Salisbury Plain <ul><li>R&amp;D in collaboration with Leica </li></ul><ul><li>Effectiveness as topographic survey tool where vegetation is present </li></ul><ul><ul><li>Automated vegetation removal </li></ul></ul><ul><ul><li>Manual workflows </li></ul></ul>
  • 33. Tree graffiti <ul><li>Record and enhance tree graffiti </li></ul><ul><ul><li>Historical WWI and WWII graffiti warped by tree growth </li></ul></ul><ul><li>Unwrapping &amp; regression </li></ul><ul><ul><li>Challenging! </li></ul></ul>
  • 34. Amesbury Archer bones <ul><li>Morphological analysis of skull </li></ul><ul><ul><li>Cross-sections </li></ul></ul><ul><ul><li>Measurements </li></ul></ul><ul><ul><li>Profiles </li></ul></ul>
  • 35. Stonehenge carvings Left: (top to bottom) stone 3, stone 3 with ‘axes’ highlighted, stone 53 and stone 4 Above: stone 3 lit from below Right: accessibility shading
  • 36. Integration &amp; Analysis: GIS <ul><li>Integrate multiple sources </li></ul><ul><ul><li>Aerial photos, survey data, remote sensing, terrains, HER data, OS data, etc </li></ul></ul><ul><li>GIS-based analysis </li></ul><ul><ul><li>Viewshed &amp; visual sensitivity </li></ul></ul><ul><ul><li>Water flow &amp; hydrology </li></ul></ul><ul><ul><li>Erosion/Deposition models </li></ul></ul><ul><ul><li>Slope/Aspect/Elevation calculations </li></ul></ul><ul><ul><li>Cross-sections and profiles </li></ul></ul><ul><li>Environment Agency LiDAR DTMs </li></ul><ul><ul><li>Detailed terrain models ideally suited </li></ul></ul><ul><ul><li>Unfiltered data contains modern ‘clutter’ </li></ul></ul>
  • 37. fin <ul><li>Thanks to: </li></ul><ul><ul><li>English Heritage </li></ul></ul><ul><ul><li>Archaeoptics </li></ul></ul><ul><ul><li>3D Laser Mapping </li></ul></ul><ul><ul><li>Kubit </li></ul></ul><ul><ul><li>LatimerCAD </li></ul></ul><ul><ul><li>Environment Agency </li></ul></ul><ul><ul><li>Warner Land Surveys </li></ul></ul><ul><ul><li>Leica </li></ul></ul><ul><ul><li>Tamworth Borough Council </li></ul></ul><ul><ul><li>Weymouth &amp; Portland Borough Council </li></ul></ul><ul><ul><li>National Trust </li></ul></ul><ul><ul><li>Aspire Defence </li></ul></ul><ul><ul><li>Defence Estates </li></ul></ul>For more info: www.wessexarch.co.uk/geomatics www.archaeogeomancy.net

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