@ARTICLE{Vassilopoulou02,
  author = {S. Vassilopoulou and L. Hurni and V. Dietrich and E. Baltsavias and
	M. Pateraki and E. Lagios and I. Parcharidis},
  title = {Orthophoto generation using IKONOS imagery and high-resolution DEM:
	a case study on volcanic hazard monitoring of Nisyros Island (Greece)},
  journal = {ISPRS Journal of Photogrammetry and Remote Sensing},
  year = {2002},
  volume = {57},
  pages = {24 - 38},
  number = {1-2},
  doi = {DOI: 10.1016/S0924-2716(02)00126-0},
  abstract = {Georeferenced high-resolution satellite images can be used for acquisition
	of topographic information, navigation and visualisation for various
	environmental studies. The present study is part of the multidisciplinary
	EU project GEOWARN related to monitoring, warning and emergency planning
	for volcanic hazards in the island of Nisyros, Greece. Here, the
	main aim was the orthorectification of a 1-m resolution pan-sharpened
	IKONOS Geo image of Nisyros island. For the orthorectification, a
	digital elevation model (DEM) with a cell size of 2 m and an RMS
	accuracy of ca. 3.5 m was used, as well as 38 selected ground control
	points (GCPs) measured with differential GPS. An object-to-pixel
	space transformation using the ground control points was computed
	using two different models, a relief-corrected affine transformation
	and the polynomial mapping functions of Kratky. These transformations
	were used for orthorectification and the orthophoto accuracy was
	evaluated using GCPs as check points. Postprocessing for radiometric
	improvement of the orthophotos was applied. The orthophoto and the
	DEM served as basic tools for subsequent base mapping and visualisation.},
  issn = {0924-2716},
  keywords = {IKONOS},
  url = {http://www.sciencedirect.com/science/article/B6VF4-477FRDC-3/2/ffa34e31f10870c0b784d5abaca80178}
}