M. Shahbazi; A. Mansourian
Abstract
Geological data are used in a variety of applications. These data have three dimensional (3D) nature and hence 3D modeling, storage, dissemination and presentation of the data not only provide a better understanding of the current situation and the relationship between different features and data layers, ...
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Geological data are used in a variety of applications. These data have three dimensional (3D) nature and hence 3D modeling, storage, dissemination and presentation of the data not only provide a better understanding of the current situation and the relationship between different features and data layers, but also increase the reliability of decisions. 3D Web Geographical Information Systems (3D Web GIS) are proper tools for managing and sharing geological data. However, current activities on developing geological Web GISs have paid less attention on 3D nature of geological data. In other words, most of the existing geological Web GISs are studied or established based on two dimensional data.
One of the important challenges for dissemination of 3D geological data in Web relates to utilization of a proper format for rendering 3D data in Web browsers. Such a format should have the capability of: 1- Conveying geological data, three dimensionally, in Web environment, 2- being displayed by Web browsers, 3- being standard and the standard to be clear for data producers in such a way data conversion to the desired format being possible, 4- conveying attribute data, and 5- providing users with the possibility of querying and analyzing data. Up to the knowledge of the authors, there is not currently any software which can disseminate 3D geological data in Web by employing a proper format respecting all of the above criteria. This paper proposes utilizing X3D, developed by Web 3D Consortium, as a standard text-based format for dissemination and rendering 3D data in Web. Although the format has not been developed for GIS purposes, in this research the applicability of that for modeling and presenting 3D geological data in 3D Web GIS is investigated.
A. Mansourian; M. Zareinejad; E. Moghimi; S. Omidian
Abstract
Damavand volcano is one of the most important geological features in Iran. Although a variety of studies are available about this volcano, there are different problems associated with existing data from Damavand including: they are not stored in a consistent and organized way, they are not directly ...
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Damavand volcano is one of the most important geological features in Iran. Although a variety of studies are available about this volcano, there are different problems associated with existing data from Damavand including: they are not stored in a consistent and organized way, they are not directly applicable in users' information systems (such as GIS), and they are not easily accessible and sometimes not accessible to users. In addition, clear and accurate studies about geomorphological-environmental specifications of Damavand are not still available. Considering these facts, this paper aims to describe design and implementation of Damavand geomorphological-environmental database and then disseminating it using WebGIS. In this research project, firstly, required spatial and attribute data were identified. Then, using available maps, satellite imageries, aerial imageries, and field works, required data were produced, completed and complemented. After that, the proposed database was designed and implemented and finally the mentioned data were stored in the database. By conducting these stages, the Damavand geomorphological-environmental database was established. At the next stage, an interactive WebGIS was designed and implemented in Geological Survey of Iran (GSI). At the last stage, the database was linked to the WebGIS and disseminated via that. At the time of writing this paper, the Damavand WebGIS and hence the geomorphological-environmental database is accessible via GSI intranet. The WebGIS can also be connected to internet in order to make the database accessible for public. Establishing such database for other geological-related datasets and its dissemination using WebGIS can significantly resolve current problems associated with these datasets from storage, accessibility and applicability perspectives.
M. Dehghani; M. J. Valadan Zouj; A. Mansourian
Abstract
study several 2D and 3D math models have been tested in order to correct slant range SAR data geometrically. Some of these models consider the imaging geometry at the time of imaging while the others relate the ground space to the image one by mathematical polynomials. The images used here are 3 ENVISAT ...
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study several 2D and 3D math models have been tested in order to correct slant range SAR data geometrically. Some of these models consider the imaging geometry at the time of imaging while the others relate the ground space to the image one by mathematical polynomials. The images used here are 3 ENVISAT ones of Bam area. In order to extract the 3D GCPs, a topographic map with a scale of 1:25000 and SRTM DEM were used. The 2D math models used in this study include Global polynomial, Point wise, Piece wise and Projective while the 3D models are DLT and Rigorous SAR model. Since the images used in this study were originally ordered for interferometry studies, their baseline is so small that the precision of 3D coordinates extraction is not satisfactory enough. However, the results of 2D models are much better.
