3D MAPPING OF THE NASCA LINES

University of Applied Sciences DresdenFaculty of Spatial InformationProf. Dr.-Ing. Bernd TeichertMSc (GIS) Christiane Richter

The basis for the photogrammetric survey are 179 aerial photos (B/W, scale 1:10.000) covering the main area of the Pampa of Nasca. The images, acquired in 1998, were provided by the University ETH Zurich/ Switzerland and scanned with a resolution of 20 microns.

After determining Ground Control Points (GCP) with GPS measurements the Aerotriangulation was computed by using the software ERDAS Imagine LPS. The accuracy of the Aerotriangulation is shown in Tab. 1. The number of GCP and Control Points (CP) respectively the number of ob-servations are added in parenthesis.

Fig. 3: Aerial image block incl. GCP and CP

One of the most fascinating mysteries of the world are the famous Nasca Lines (200 BC – 650 AC) in southern Peru. Today this unique artwork is threatened with destruction. Therefore the major aim of the Nasca project at the University of Applied Sciences Dresden is the preservation of this cultural heritage at least in digital form. For that reason a NascaGIS application was developed. The primary requirements of any GIS application are the data. This poster shows the photogrammetric approach as one of the most practical solutions to capture data.

Fig. 6: 3D view of the Pampa of Nasca and Ingenio valley (Anaglyph image)

Problems occurred while using the automated tie point extraction, because approx. 80% of the images are cove- ring low textured areas (desert). Therefore most of the tie points were measured manually.

Fig. 3 shows the result of the aerotriangulation including the GCP and CP’s measured with GPS.

Aerotriangulation

Ground [m] Image [Pixel]RMS(x) RMS(y) RMS(z) RMS (x) RMS(y)

GCP 0.103 (39) 0.091 (39) 0.131 (38) 0.658 (186) 0.662 (186)CP 0.302 (9) 0.155 (9) 0.267 (8) 0.463 (52) 0.520 (52)

Fig. 4: Manually corrected DTM

Fig. 5: Orthophoto mosaic

Fig. 7: 3D mapping of the Nasca Lines

DTM Generation

3D Mapping

After finishing the aerial triangulation a Digital Terrain Model (DTM) was generated (Fig. 4). All experiments of fully automatic DTM extraction failed because the surface of the desert is very homogeneous in texture and the con-trasts are too insignificant. That means the photogramme- tric DTM generation had to be corrected manually by using ERDAS Imagine LPS. Fig. 1 compares the automatically derived DTM with the manually corrected DTM.

Because the main objective of the Nasca project consists in the development of the NascaGIS, the most important task is the vector data capture of the ground drawings at the Pampa of Nasca. Therefore all the lines and figures of this region were completely mapped with high accuracy for the very first time (Fig. 2 and Fig. 7).

Fig. 1: Automatic derived DTM (left); manually corrected DTM (right)

Tab.1: Accuracy of Ground Control Points (GCP) and Check Points (CP)

Orthophoto mosaicBased on the Aerotriangulation and the DTM an ortho-

photo mosaic with a resolution of 25 cm was generated (see Fig. 5).

Now it’s possible to realize 3D views and virtual over-flights based on the DTM and the orthophoto mosaic. Two examples are shown in Fig. 6 and Fig. 7. The mosaic is also used for the production of orthophoto maps (Fig. 2).

0 150 30075 Meter

Fig. 2: Mapping of the Nasca Lines

Unfortunately the photogrammetric data are covering only the center area of the Pampa of Nasca. For this reason the use of very high resolution satellite data is an alterna-tive to capture data in the remaining region. Therefore satellite data (Ikonos, QuickBird, GeoEye-1 and Worldview-2) of the entire area were bought.

All the data and information about the lines and figures of the Pampa of Nasca and Palpa are stored in the Nasca-GIS. In order to provide an easy digital access to this famous cultural heritage, the NascaGIS is presented as an user friendly Internet (WebGIS) application for everybody. For further information see: www2.htw-dresden.de/nazca/

Hochschule für Technik und WirtschaftDresdenUniversity of Applied Sciences