Heinz Rüther - UCT

State-of-the-art-technologiesin

Heritage Documentation

The Giraffe Engravingsof Oued Djerat

a TARA project

Heinz RütherUniversity of Cape Town

Geomatics Division

Heinz Rüther - UCT

The field team:

David CoulsonAlec CampbellVictoria WaldockHeinz Rüther

Tuareg GuidesGiraffes

Tasili N’A

jjer

Heinz Rüther - UCT

Technologies employed

1. Aerial & close range digital photogrammetry

2. Satellite imagery, remote sensing and imageprocessing

3. (Laser scanning)

4. Airborne and close range SAR

5. Geographic Information Systems (GIS) and CAD

6. Computer visualisation

7. Data bases

8. Conventional surveying methods

Heinz Rüther - UCT

Heinz Rüther - UCT

Heinz Rüther - UCT

Heinz Rüther - UCT

Photogrammetry

DistortedOriginalImages

Camerastations

Scale discrepancies due to elevation differences

h2

h1

h1 h2

Scale 1 Scale 2

y z

x

Ortho Image Generation

Ortho-rectifiedImages

Camera position and orientation(x, y, z, )

Digital Terrain Model

Heinz Rüther - UCTladder = photo centreunused photo area

Four photos at each setup

• one vertical for final composite

• three oblique to tie images together

Heinz Rüther - UCT

7 * 7 = 49 camera setups with 60% overlap of the verticalimages

Total of about 200 images

Heinz Rüther - UCT

Heinz Rüther - UCT

Heinz Rüther - UCT

Heinz Rüther - UCT

Heinz Rüther - UCT

5000 by 5000 pixels 1 pixel 3 mm

Heinz Rüther - UCT

Linedrawings

in

GIS

format

Heinz Rüther - UCT

Heinz Rüther - UCT

Heinz Rüther - UCT

Heinz Rüther - UCT

Heinz Rüther - UCT

Heinz Rüther - UCT

Characteristics of terrestrial scanners

Range: 3 - 50 to 800 m

Accuracy: 5-10 mm depending on distance

Minimum point interval : 1 mm

Recent additions to scanners:

Camera with RGB capability

GPS

Heinz Rüther - UCT

15 m

15

m

Laser scan - Low resolution

at 1 mm point spacing

15 000 * 15 000

= 125 000 000 points

X Y Z intensity

= 500 000 000 stored values

or = 875 000 000 with RGB

??? DISPLAY ???

Laser Scan for the Giraffe site

High resolutionclose range

laser

0.4 by 0.4 mcover per

scan > 1000

Set ups

Laser scanning not suitable for giraffe site

Laser scanning not suitable for giraffe site

Heinz Rüther - UCT

Surface representation in laser scan software

Zoomed

out:

Gaps

Best fit Zoomed

in

Smeared

TIN

Heinz Rüther - UCT

Heinz Rüther - UCT

Heinz Rüther - UCT

Heinz Rüther - UCT

Heinz Rüther - UCT

Heinz Rüther - UCT

Heinz Rüther - UCT