FIG Peer Review Journal


From Spot Heights to Cell Heights: the Processing and Dynamics of the Digital Elevation Model Data Structures (6916)

Akajiaku Chukwuocha and Ngozi Ac-Chukwuocha (Nigeria)
Dr. Akajiaku Chukwuocha
Federal University of Technology, Owerri, Nigeria
Department of Surveying and Geoinformatics,
Federal University of Technology, Owerri
Corresponding author Dr. Akajiaku Chukwuocha (email: achukwuocha[at], tel.: +2348033398505)

[ abstract ] [ paper ] [ handouts ]

Published on the web 2014-03-21
Received 2013-11-15 / Accepted 2014-02-06
This paper is one of selection of papers published for the FIG Congress 2014 in Kuala Lumpur, Malaysia and has undergone the FIG Peer Review Process.

FIG Congress 2014
ISBN 978-87-92853-21-9 ISSN 2308-3441


ABSTRACT Over the years the study and accurate determination of point elevations and topographic forms of land spaces and sea beds have been the exclusive preserve of Surveyors, Geodesists and Hydrographers and in a derivative sense, Cartographers. Research into diverse environmental phenomena is growing by the day as continuously improving credible results are obtained from computer based Digital Terrain Analysis (DTA), leading to fundamental shifts in engineering solutions and designs and social options in managing the environment. Digital Elevation Models (DEMs) are basic input for the development of Digital Terrain Models (DTMs) which seeks to classify terrain characteristics and behavior for prediction of future environmental phenomena. A continuous digital topographic data structure, the DEM, is foundational to efficient analysis of the landscape as is needed in line of sight determination and in the analysis of topographically influenced environmental phenomena such as, flooding, erosion, stream flow, sediment transportation, runoff distribution etc. The growing efforts today are to express topographic data in continuous digital data structures that either assign an elevation value to every unit of land space, usually in fixed cell sizes, or provide the basic data and algorithm for continuous computation of irregularly sized and sloping triangles across the landscape. These new efforts are purely computational. They are however extending the use of topographic analysis in other vastly expanding areas such as 3-D computer graphics for anatomy and surgery, 3-D movie creations, and 3-D computer printing. A basic fact that makes the involvement of Surveyors imperative in Digital Elevation Model research and development is the proficiency required for adaptation of different geoid models, issues of topo data source scales and accuracy and data geolocation. This paper reviews a few steps of processing different traditional topo data structures to Digital Elevation Models. It makes a few comparisons between the evolving DEM forms and discusses a some applications of the DEM in environmental phenomena analysis. The paper concludes with a call for Surveyor scientists to take their rightful place in the research efforts to move from topographic data structure of discrete spot heights or firm contour lines to dynamic forms of continuous digital topographic data structure, the DEM. A further imperative of this paper is the need to review topographic surveying training curricula to equip upcoming Surveyors with the required skills for DEM development.
Keywords: Curricula; Spot height; Contour; Digital Elevation Model (DEM; Digital Terrain Model (DTM); Digital Terrain Analysis (DTA); Triangulated Irregular Network (TIN); Surveyors; Environmental phenomena