McDonald Institute for Archaeological Research, University of Cambridge, May 2005




            Of Henges, Rock Art & La...
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




Presentation Outline
    Background...
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




Background
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




Introduction
   Project initiated t...
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




      The Project Team and those inv...
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




Aims & Objectives


1.   To assess u...
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




Equipment used

   Riegl Z360 ‘Time...
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




    Related Work at Stonehenge
   E...
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




Historical Context
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




Stonehenge
   Located on Salisbury ...
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




Stonehenge

   Part of a complex
  ...
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




The Prehistoric Carvings
   First o...
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




    Previous work on the carvings
 ...
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




Methodology; Data Capture & Processi...
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




Scanning Technologies
   Two system...
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




Time-of-Flight scanners
   Fire a l...
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




Triangulating Scanners
   Fire a la...
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




Airborne scanners
   Time-of-flight...
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




Laser-scan datasets - points
   Raw...
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




Laser-scan datasets - processing
  ...
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




Registration
   Multiple datasets m...
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




Decimation
   Sheer volume of data ...
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




Decimation – surfaced model
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




Decimation - wireframe
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




The Real World
   Data can be place...
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




Methodology; Analysis
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




From Points to Digital Surface Model...
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




Lighting techniques; oblique lightni...
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




Lighting techniques; dynamic lightin...
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




Lighting techniques; dynamic lighting
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




Geometric techniques; exaggeration
...
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




Geometric techniques; accessibility
...
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




Geometric techniques; range colourin...
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




Results
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




The Henge; time-of-flight scan
   S...
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




    The Henge; increasing resolution...
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




Stone 3 carvings
   The lower left ...
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




Stone 4 carvings
   The greatest nu...
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




Stone 53 carvings
   The famous dag...
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




Stone 53 carvings
   A comparison
 ...
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




Stone 53 carvings
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




    LiDAR
   Possible to
    identi...
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




LiDAR - animation
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




Conclusions
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




Laser-scanning

 A very useful surv...
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




The prehistoric carvings

 Current ...
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




Future work

 Evaluation successful...
McDonald Institute for Archaeological Research, University of Cambridge, May 2005




fin

              For more informat...
Upcoming SlideShare
Loading in …5
×

Of Henges, Rock Art & Lasers; An application of Laser-Scanning techniques at Stonehenge

1,809 views
1,617 views

Published on

A presentation given in May 2005 at the McDonald Institute for Archaeological Research, University of Cambridge, on behalf of the Stonehenge Laser Scan project team. The presentation was aimed at highlighting some of the results and well as the technologies used.

Published in: Education, Technology, Business
0 Comments
3 Likes
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total views
1,809
On SlideShare
0
From Embeds
0
Number of Embeds
8
Actions
Shares
0
Downloads
0
Comments
0
Likes
3
Embeds 0
No embeds

No notes for slide

Of Henges, Rock Art & Lasers; An application of Laser-Scanning techniques at Stonehenge

  1. 1. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 Of Henges, Rock Art & Lasers… An application of Laser-Scanning techniques at Stonehenge, Wilts. Paul Cripps GIS Specialist, Archaeological Projects, English Heritage Postgraduate Research Student, Archaeological Computing Research Group (ACRG), University of Southampton On behalf of the Project Team
  2. 2. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 Presentation Outline  Background  Project Team  Aims & Objectives  Equipment used  Related projects  Methodology 1; Data Capture & Processing  Terrestrial Laser-Scanners and Airborne LiDAR  Large datasets!  Registration  Decimation  Methodology 2; Analysis of Results  Three-dimensional digital surface models (DSM)  Geometric transformation & analysis  Lighting & Shading  Animation  Results  The Henge  Stone 53 carvings  Stone 3 carvings  Stone 4 carvings  LiDAR  Conclusions  Review of aims & objectives  Potential for Rock Art research
  3. 3. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 Background
  4. 4. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 Introduction  Project initiated to assess usefulness of commercial laser-scanning techniques to an archaeological unit  Brought together an archaeological unit and commercial laser-scanning companies  Used a range of techniques on nearby sites for evaluation purposes
  5. 5. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 The Project Team and those involved  Wessex Archaeology:  Chris Brayne (IT Manager)  Thomas Goskar (Multimedia Development Officer)  Paul Cripps (Systems Development Officer)  Archaeoptics:  Alistair Carty (Director)  Dave Vickers (Technician)  3D Laser Mapping  Dr. Graham Hunter (Managing Director)  English Heritage:  Paul Cripps (GIS Specialist, Stonehenge & Avebury World Heritage Site GIS) With special access to the stones granted by English Heritage
  6. 6. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 Aims & Objectives 1. To assess usefulness of terrestrial (& airborne) laser- scanning techniques as survey tools 2. To record the known inscribed rock art at Stonehenge 3. To assess the potential for future work at Stonehenge
  7. 7. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 Equipment used  Riegl Z360 ‘Time-of-Flight’ scanner  Basically a super-TST  360° horizontal scanning range  90° vertical scanning range  Relatively low resolution  Minolta VI-900 ‘Triangulating’ scanner  Behaves more like a camera, recording position of an emitted stripe of laser light  Very high 170µ resolution (0.17mm)
  8. 8. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 Related Work at Stonehenge  English Heritage Aerial Survey Team  Looked at the Environment Agency LiDAR dataset in collaboration with Cambridge University (Colin Shell)  Mini-project to assess use of LiDAR as a prospection tool for archaeological features, similar to aerial photograph transcription  English Heritage’s Stonehenge 3D  Collaboration with Intel & IBM  Used photogrammetric model of the stones as 3D source data (English Heritage Metric Survey Team)  Terrain model derived from OS LandForm data
  9. 9. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 Historical Context
  10. 10. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 Stonehenge  Located on Salisbury Plain  Part of the Stonehenge & Avebury World Heritage Site  Multi-phase henge  Earliest phase Middle Neolithic: bank and ditch with wooden posts inserted into bank in the Aubrey Holes  Second phase Late Neolithic: remodelling of ditches, wooden posts within henge, Aubrey Holes partially silted up  Third phase Late Neolithic/ Early Bronze Age: Bluestone and Sarsen megaliths added
  11. 11. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 Stonehenge  Part of a complex archaeological landscape  Surrounded by approx. 700 individual monuments; barrows, cursuses, enclosures, henges, field systems, etc  Archaeology from all periods from prehistory to modern airfield
  12. 12. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 The Prehistoric Carvings  First observed in 1953 (Atkinson, 1953; Crawford, 1954; Atkinson, 1979 pp43-4)  Found on the Sarsen stones  Sarsens thought to have been brought from Marlborough Downs, nr. Avebury  Likely to have been carved after erection of the stones based on distribution  Thought to represent Bronze Age axes and daggers  Axe almost identical to carvings found in nearby Bush Barrow, deposited wrapped in cloth  Other sarsens near Avebury show axe grinding marks
  13. 13. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 Previous work on the carvings  Robert Newall took casts and rubbings of carvings on stones 3 & 4  43 casts (mainly by Newall) stored in Salisbury Museum  1967 Atkinson took latex mould of part of Stone 53, subsequently stereo-photographed and used to produce a 0.5mm contour plot (Atkinson, 1968)  Photogrammetric survey (Bryan & Clowes, 1997) led to renewed interest in carvings, with a project outline (1999) by Burton, Pitts & Wheatley (never initiated)
  14. 14. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 Methodology; Data Capture & Processing
  15. 15. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 Scanning Technologies  Two systems used on site:  Time-of-flight scanner  Triangulating scanner  Data from a third system incorporated  Airborne LiDAR, produced by the Environment Agency, provided by English Heritage
  16. 16. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 Time-of-Flight scanners  Fire a laser beam, measure time taken for beam to return  Records bearing from scanner  Uses speed of light constant c to calculate range  Also records other properties of reflected laser beam (eg intensity) http://www.i3mainz.fh-mainz.de/publicat/cipa2001/cipa2001.pdf
  17. 17. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 Triangulating Scanners  Fire a laser beam from a known point  Observe laser beam from a known displacement  Use triangulation principles to calculate x,y,z location on target relative to scanner  Much higher resolutions  Digital camera can also be used to capture photographic information http://www.i3mainz.fh-mainz.de/publicat/cipa2001/cipa2001.pdf
  18. 18. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 Airborne scanners  Time-of-flight systems attached to an aircraft  Incorporates dGPS for location and uses onboard sensors to detect orientation and aspect  Calculate x,y,z location on target  Transform data to any coordinate system (eg British National Grid)
  19. 19. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 Laser-scan datasets - points  Raw data made up of thousands of recorded points (a ‘point cloud’)  Each point has x,y,z locations (plus other attributes)  Very large filesizes (100,000 points captured per second on some systems!)  Difficult to visualise complex datasets http://www.archaeoptics.co.uk/downloads/presentations/m3/6.html
  20. 20. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 Laser-scan datasets - processing  Point clouds require processing  Can be seen as a statistical distribution representing probability of a surface occupying a particular space  Possible to fit a surface to the point cloud using best-fit algorithms…  …or force a geometric primitive to fit (makes assumptions)  Surfaces much easier to manipulate; hardware acceleration on graphics cards aimed at gaming is ideally suited to manipulating surface data  Better representation of the real-world situation
  21. 21. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 Registration  Multiple datasets must be ‘stitched’ together  Can be accomplished using control points http://www.pobonline.com/CDA/ArticleIn placed in each scan… formation/Article/1,9169,83255,00.html  …or by matching the surfaces within controlled parameters…  … or a combination http://www.research.ibm.com/vgc/pdf/te xalign_TVCG.pdf
  22. 22. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 Decimation  Sheer volume of data can be unusable  Many millions of polygons  Process called decimation reduces level-of-detail according to usage requirements  Different levels of detail required for different purposes eg rock art analysis, web dissemination, desktop visualisation, etc
  23. 23. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 Decimation – surfaced model
  24. 24. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 Decimation - wireframe
  25. 25. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 The Real World  Data can be placed in real-world coordinates (eg British National Grid)  Allows multiple datasets to be placed in a common coordinate system (eg airborne LiDAR, close range scans, time-of-flight scans, other DTMs, photogrammetric surveys, geophysical survey data, etc)  Facilitates integration with GIS
  26. 26. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 Methodology; Analysis
  27. 27. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 From Points to Digital Surface Model  Triangle mesh produced from point cloud  This digital surface model can be manipulated in a virtual 3D world  Ideally suited to rock art analysis:  Oblique lighting techniques  Dynamic lighting techniques  Geometric analysis http://www.polygon-technology.com
  28. 28. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 Lighting techniques; oblique lightning  Low angle light source emphasises carvings  Easy to control, unlike in the real- world; not dependent on external factors
  29. 29. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 Lighting techniques; dynamic lighting  A moving light source can highlight otherwise imperceptible surface features  Our eyes highly attuned to detecting subtle changes in light and shadow
  30. 30. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 Lighting techniques; dynamic lighting
  31. 31. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 Geometric techniques; exaggeration  A digital surface model can be manipulated in 3D space  Vector based transformations X1  Including stretch along z- axis or vertical exaggeration X 10
  32. 32. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 Geometric techniques; accessibility shading  Possible to code surface according to accessibility  Use balls of varying sizes to probe surface  More accessible locations receive greater score
  33. 33. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 Geometric techniques; range colouring  Possible to code surface according to range from viewpoint…  … or specified plane or point  Range in this image from black to white: 5mm
  34. 34. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 Results
  35. 35. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 The Henge; time-of-flight scan  Single 360° scan undertaken from central location within Henge  Provides spatial framework for detailed scans
  36. 36. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 The Henge; increasing resolution Animation  Gives the impression of a ‘complete’ henge when viewed from scanner location  Animation shows transition between datasets in the same coordinate system
  37. 37. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 Stone 3 carvings  The lower left part of the outer face of Stone 3 contains the carvings of three axe heads.  These can be seen with the naked eye when close to the stone, and were easily picked up by the scanner.
  38. 38. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 Stone 4 carvings  The greatest number of carvings on any one stone at Stonehenge is on the outer face of Stone 4  The annotations indicate the locations of carvings
  39. 39. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 Stone 53 carvings  The famous dagger and axe are clearly visible in the centre of the scan  As is the historical graffiti  And two seams in the sandstone
  40. 40. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 Stone 53 carvings  A comparison with Newall’s recording shows two previously undiscovered carvings  Very shallow and indistinct compared to known carvings
  41. 41. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 Stone 53 carvings
  42. 42. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 LiDAR  Possible to identify and quantify extant archaeology  Some new features identified  Require validation
  43. 43. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 LiDAR - animation
  44. 44. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 Conclusions
  45. 45. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 Laser-scanning  A very useful survey tool, complements tools already in use  Rapid data acquisition  Ideal for recording surfaces  High resolution, suitable for recording ephemeral carvings  True 3D data ideal for analysis  Erosion monitoring & volumetric analysis
  46. 46. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 The prehistoric carvings  Current records are incomplete; many more carvings than are currently known  The carvings have been considerably eroded since first carved, arguably since recorded in 1950’s  Accurate recordings of morphology of axe & dagger carvings
  47. 47. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 Future work  Evaluation successfully highlighted potential of technique  Systematic survey of all stone surfaces at sub-millimetre accuracy (new scanners capable of 80µ resolution)  Aim: to provide a 3D baseline dataset for management and research purposes
  48. 48. McDonald Institute for Archaeological Research, University of Cambridge, May 2005 fin For more information: www.stonehengelaserscan.org With thanks to Tom Goskar and Alistair Carty for their assistance with this presentation

×