Specifically, the objective of this case study was to answer the following questions:
I) What is the accuracy of the DEM created from archive aerial photos in comparison
with two other DEMs generated with different methodologies?
II) How do slope and aspect influence DEM accuracy?
Material and methods
Study area
The study area is located about 30 km south of Cagliari, in southern Sardinia, Italy, around
38º 59’ north latitude and 8º 54’ west longitude, and covers an area of 10 km x 5 km. The
elevations range from 4 m up to over 860 m a.s.l., the average slope is 22° and most of
the reliefs are facing south-east. Land cover consists mainly of a mixture of coniferous
forest and mediterranean maquis, with patches of pastures and agricultural areas. The site
is dominated by Quercus ilex L., Quercus suber L., Arbutus unedo L. and Phillyrea L. sp.
with a maximum height of 3 m. Paleozoic Granites (Complesso Granitoide del SulcisArburese)
constitute the bedrock. They are deeply altered and friable, showing the typical
arenization at the surface. Limited Pleistocene and Holocene sediment covers are present
in the lower valley areas. This region is characterized by hilly and undulating terrain which
extends to the coastline, and represent a specific landscape characterized by steep ridges,
high peaks, deep valleys and gorges. Figure 1 depicts the study area and the locations of the
CPs collected from a topographic map with a scale of 1:10.000.