Ralf Hesse, State Office for Cultural Heritage Baden-Württemberg

STATE OFFICE FOR CULTURAL HERITAGE

Visualising geomorphological traces of conflict

in high-resolution elevation models

Conflict archaeology, remote sensing and geomorphol ogy

Of all search results containing „conflict archaeology“...

• 47.7 % also contained „battlefield“

• 6.4 % also contained „remote sensing“

• 3.9 % also contained „geomorphology“

• 2.0 % also contained „remote sensing“ AND „geomorphology“

DEM visualisation techniques - why?

• What is a DEM?

DEM visualisation techniques - why?

• What is a DEM?

a (gridded) data set containing elevation values

���� has to be converted into a human-readable image

Shaded Relief• directional illumination from a point light source

• specified azimuth and elevation (Imhof, 2007)

Shaded Relief• directional illumination from a point light source

• specified azimuth and elevation (Imhof, 2007)

Exaggerated Relief• Rusinkiewicz et al., 2006

• based on simple Shaded Relief, but

• multi-scale approach

• locally adapted illumination elevation

• combined by weighted mean

Exaggerated Relief• pro:

• single illumination direction

• no overly dark or bright areas

• contra:

• loss of landscape forms

• apparent ridges

Trend Removal• subtraction of a smoothed (low-pass-filtered) version from the original DEM

• pro:

• highlights small topographic differences

• contra:

• loss of landscape forms

• apparent banks and ditches

Local Relief Model (LRM)• advanced trend removal method

1.6

0 m

-3.7

0 175 m0 175 m

1.6

0 m

-3.7

Extraction

0 175 m

440

70 m

Interpolation

0 175 m

440

0 m

Difference map

0 175 m

8.7

0 m

-8.6

Local Relief Model (LRM)• pro:

• highlight small topographic differences

• contra:

• complexity, computation time

• loss of landscape shapes

• apparent banks and ditches

Sky-View Factor (SVF)• diffuse illumination from a homogeneously bright hemisphere (Zakšek et al.,2011)

(Zakšek et al. 2011, Fig. 6)

Sky-View Factor (SVF)• pro:

• intuitively readable

• single illumination

• negative relief features and features on slopes very well visbile

• contra:

• not suitable for low positive relief features and low features on horizontalplanes

Openness• diffuse illumination from a homogeneously bright sphere centered on eachpixel (Yokoyama et al., 2002; Doneus, 2013)

(Yokoyama et al., 2002, Fig. 5)

Openness• pro:

• good depiction of relief details

• contra:

• loss of landscape forms

positive openness:

Openness• pro:

• good depiction of relief details

• contra:

• loss of landscape forms

negative openness:

Accessibility• What is the diameter of the largest sphere that can be placed on the surface?(Miller, 1994)

Accessibility• pro:

• intuitively readable

• relief detail as well as landscape forms

• contra:

• not suitable for horizontal planes

• difficult to establish suitabel contrast stretch

Local Dominance• How dominant is an observer with regards to the local surroundings?

Local Dominance• pro:

• good depiction of detail

• contra:

• different contrast stretch necessary for horizontal/sloping terrain

Cumulative Visibility

• What percentage of the area (within a given radius) is visible?

Cumulative Visibility

• pro:

• good depiction of detail (when choosing low radius)

• analytical tool for site and landscape interpretation• contra:

• level of detail depends on chosen radius

Multi-Scale Integral Invariants (MSII)• for n spheres with different diameters, centered on each DEM pixel, thepercentage of each sphere above and below the DEM surface is computed

• the resulting sets of n values for each pixel are interpreted as n-dimensionalvectors, and the distance to a reference vector can be computed (Mara et al.,2010)

Multi-Scale Integral Invariants (MSII)• pro:

• good depiction of detail

• contra:

• loss of landscape shapes

Laplacian-of-Gaussian

• Laplacian filter: edge detection filter (Mlsna & Rodríguez, 2005)

• pro:

• good depiction of detail

• fast algorithm

• contra

• loss of landscape shapes

LiVT – an Open Source toolbox for DEM visualisation

• stand-alone software that computes various visualisations

• spatial filters (incl. Laplacian of Gaussian)

• Shaded Relief

• Sky-View Factor

• Trend Removal

• Local Relief Model

• Exaggerated Relief

• Local Dominance

• Accessibility

• Openness

• MSII

• Cumulative Visibility

� downloadable from: http://sourceforge.net/projects/livt/

• alternative freeware for some visualisations: Relief Visualisation Toolbox

� downloadable from: http://iaps.zrc-sazu.si/en/svf

Geomorphological traces of conflict through the age s

• (violent) conflict has been present throughout history

• geomorphological impacts have changed over time

Prehistoric to early modern conflict

• mostly defensive structures/earthworks: ramparts, moats

• fortification = conflict?

• examples:

• Neolithic and Bronze Age hilltop fortifications

• Iron Age oppida

• Roman limes

• medieval fortifications

• early modern fortifications

Prehistoric to early modern conflict

• Inca fortress Sacsayhuaman (Cusco, Peru)

point density map (photogrammetric point cloud)

Prehistoric to early modern conflict

• Iron Age oppidum „Heidengraben“

Sky-View Factor

Shaded Relief

Prehistoric to early modern conflict

• Roman limes

Prehistoric to early modern conflict

• medieval

Prehistoric to early modern conflict

• early modern: Philippsburg (War of Polish Succession, 1733-1738)

Shaded Relief

ccLRM & Shaded Relief

Prehistoric to early modern conflict

• early modern: Philippsburg (War of Polish Succession, 1733-1738)

Shaded Relief

Local Dominance

Prehistoric to early modern conflict

• early modern: Philippsburg (War of Polish Succession, 1733-1738)

Shaded Relief

Primary traces of modern industrial warfare

• mass-produced, powerful explosives and delivery to the target

• bomb and mine warfare

• trenches, tank barriers

Clusters of bomb craters

Debris mounds

Bunker remains

Tank barriers and trenches

WW II in Baden-Württemberg: bunkers, trenches, bomb craters

„Westwall“ / „Siegfried Line“

• built 1936-1940

• c. 3500 structures

� >200 bunkers

� c. 60 km trenches

� c. 10 km tank barriers

Hinterland

• bomb craters

Primary traces of modern industrial warfare

• „Westwall“ near Hügelsheim

Orthophoto Shaded Relief Local Dominance LD & SR

Primary traces of modern industrial warfare

• „Westwall“ near Müllheim

Primary traces of modern industrial warfare

• „Westwall“ near Müllheim

Primary traces of modern industrial warfare

• „Westwall“ near Rheinstetten

Primary traces of modern industrial warfare

• bomb craters (Ulm)

Primary traces of modern industrial warfare

• bomb craters (Esslingen)

Secondary traces of modern industrial warfare

• debris mounds

• Birkenkopf (Stuttgart): 0,75 Mio. m3

• Grüner Heiner (Stuttgart): 4,7 Mio. m3

• Wallberg (Pforzheim): 0,55 Mio. m3

Birkenkopf

https://plus.google.com/photos/+DieterThau/albums/5658092771702917521/5677561241283865058?pid=5677561241283865058&oid=103585898976472612049

Grüner Heiner

Secondary traces of modern industrial warfare

• debris mounds

• Birkenkopf (Stuttgart): 0,75 Mio. m3

• Grüner Heiner (Stuttgart): 4,7 Mio. m3

• Wallberg (Pforzheim): 0,55 Mio. m3

Traces of warfare without war

• military training and weapons testing facilities

• conventional: Münsingen

Local Dominance & Shaded Relief

Traces of warfare without war

• military training and weapons testing facilities

• nuclear (Nevada test site)

SR

SVF

Traces of warfare without war

• military training and weapons testing facilities

• nuclear (Nevada test site)

SR

LOG

Traces of warfare without war

• military training and weapons testing facilities

• nuclear (Nevada test site)

SR

Traces of conflict sustenance

• production of weapons etc.

• war related mining

• weapons production

• infrastructure (railways etc.)

• related housing etc.

http://www.bergmannsverein-erfurt.de

Conclusions• geomorphological traces of past conflict are common

• from prehistory to modern

• DEM visualisation techniques are important tools

• variety of techniques with advantages and disadvantages

• understanding of algorithms necessary for correct interpretation

ReferencesDevereux, B.J., Amable, G.S., Crow, P., 2008. Visualisation of LiDAR terrain models for archaeological featuredetection. Antiquity 82, 470–479.

Doneus, M., 2013. Openness as visualization technique for interpretative mapping of airborne LiDAR deriveddigital terrain models. Remote Sensing 5(12), 6427-6442.

Hesse, R. 2010. LiDAR-derived Local Relief Models – a new tool for archaeological prospection.Archaeological Prospection 17, 67–72.

Imhof, E., 2007. Cartographic relief representation. English language edition edited by H.J. Steward. Redlands:ESRI Press.

Mara, H., Krömker, S., Jakob, S., Breuckmann, B., 2010. GigaMesh and Gilgamesh – 3D Multiscale IntegralInvariant Cuneiform Character Extraction, In: Artusi, A., Joly-Parvex, M., Lucet, G., Ribes, A., Pitzalis, D. (eds.),The 11th International Symposium on Virtual Reality, Archaeology and Cultural Heritage VAST (Paris, France,2010), pp. 131–138.

Miller, G., 1994. Efficient algorithm for local and global accessibility shading. Computer Graphics Proceedings,Annual Conference Series SIGGRAPH, 319–325.

Mlsna, P.A., Rodríguez, J.J., 2005. Gradient and Laplacian edge detection. In: Bovik, A.C. (ed.), Handbook ofimage and video processing. 2nd. edition. Elsevier, Amsterdam. pp. 535–553.

Rusinkiewicz, S., Burns, M., DeCarlo, D., 2006. Exaggerated Shading for depicting shape and detail. ACMTransactions on Graphics (Proceedings SIGGRAPH) 25(3), 1199–1205.

Yokoyama, R., Shirasawa, M., Pike, R.J., 2002. Visualizing topography by openness: a new application ofimage processing to digital elevation models. Photogrammetric Engineering & Remote Sensing 68(3),257–265.

Zakšek, K., Oštir, K., Kokalj, Z., 2011. Sky-View Factor as a relief visualisation technique. Remote Sensing 3,398–415.

LIDAR data: LGL/LAD Baden-Württemberg