Heritage management and ALS - Progress and challenges in Baden-Württemberg

Ralf Hesse, State Office for Cultural Heritage Baden-Württemberg

STATE OFFICE FOR CULTURAL HERITAGE

Heritage management and ALS

Progress and challenges in Baden-Württemberg

ALS-based archaeological prospection

Scope of the project:

spatially complete prospection of Baden-Württemberg (35,751 km2)


Challenge 1: data management and data processing

• > 1 TB in ~160,000 files

• vegetation-filtered point cloud

• no suitable software

development of user surfaces and data management/processing tools


Challenge 2: data quality


Challenge 3: rapid mapping of large areas


Challenge 3: rapid mapping of large areas

Challenge 4: “finding hills in the mountains”

application and development of appropriate visualisation techniques

Shaded Relief

•pro:

• intuitively readable

• very adaptable

• contra:

• multiple illumination directions required

• optical illusions for illumination azimuths 90-270°

Exaggerated Relief

• pro:

• single illumination direction

• no overly dark or bright #areas

• contra:

• loss of landscape forms

• apparent ridges

Trend Removal

• pro:

• highlights small topographic differences

• contra:


• apparent banks and ditches

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)

• pro:


• single illumination

• negative relief features and features on slopes very well visbile

• contra:

• not suitable for low positive relief features and low features on horizontal planes

Openness

• pro:

• good depiction of relief details

• contra:


Accessibility

• pro:


• relief detail as well as landscape forms

• contra:

• not suitable for horizontal planes

• difficult to establish suitable contrast stretch

Local Dominance

• pro:

• good depiction of detail

• contra:

• different contrast stretch necessary for horizontal/sloping terrain

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)

• pro:


• contra:


Laplacian-of-Gaussian

• pro:


• fast algorithm

• contra:


Visualisation techniques used in the project

• Shaded Relief

• Local Relief Model

(usually in combination with Shaded Relief)

• Sky-View Factor

• Local Dominance

• Laplacian of Gaussian

(usually in combination with Sky-View Factor or Local Dominance)

Visualisation techniques NOT used in the project (and why):

• Exaggerated Relief (computation, readabilty)

• Trend Removal (visually similar to LRM and Local Domanance)

• Accessibility (readability)

• Cumulative Visibility (computation)

• MSII (computation)

• PCA (computation, readability)

Recent progress of the project

June 2013

March 2014


• 20,700 km2

(~60% of the state’s area)

• 580,000 features mapped

March 2014


Examples

• former field boundaries


Challenge 5: What is (archaeologically) worth mapping?

• “(potential) archaeological features” vs. “archaeological sites”

• most mapped features are

• former field boundaries

• sunken roads

• “pits”

• “mounds”

Challenge 6: Verification

• impossible for 1,000,000 features

• priorities (spatial/typological) / SRS

Challenge 7: Heritage management implications

• “sites” vs. “features”

• values worth protecting?

• validity of heritage management arguments

Heritage management and ALS - Progress and challenges in Baden-Württemberg

Documents

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