uk area 
IDENTIFICATION OF DEVELOPABLE LAND USING TIN-BASED 
DIGITAL TERRAIN MODELLING 
Alias Abdul-Rahman and Ghazali Desa 
Department of Geoinformatics 
Faculty of Surveying and Real Estate 
Skudai, Johor Bahru, Johor, 
MALAYSIA. 
E-mail: alias@fu.utm.my 
ISPRS Commission IV, Working Group 4 
ABSTRACT 
Rapid physical development in most developing countries have created a number of problems to various related 
agencies. One of the problems is to identify the most suitable land for the development. This paper reports some 
preliminary results of research work using DTM for the identification. TIN data structure was selected to 
generate a DTM of a study area in Langkawi Island, Malaysia. The study shows that the identification of 
developable land can be achieved quite straight forward using TIN-based DTM and some overlay operation 
available in most GIS software. 
KEY WORDS: DTM, TIN, Digitization, Land, Use. 
INTRODUCTION 
Rapid physical development in most developing 
countries have created a number of problems to 
various related agencies especially to the local 
authorities. = Malaysia, still categorized as a 
developing nation, faces many problems in her effort 
to implement the developmental projects. One of the 
problems is to identify the most suitable land for 
physical development. This paper reports some 
preliminary results of a research works conducted 
for a local authority. Most local authority in 
Malaysia are still unaware of the potential of Digital 
Terrain Modelling (DTM) especially for the 
identification of developable land. In the project, 
Triangular Irregular Network (TIN)-based DTM was 
utilized. Map of land suitability are produced 
through the overlay function of GIS. This paper 
provides discussion on some of the prominent DTM 
data structures with a particular emphasis on TIN 
structure. Why TIN and not the other structure e.g. 
grid or random points DTM? One of the reasons is 
that the TIN structure offers more interesting 
features than the grid. For example, breaklines and 
important points can be easily accommodated. A 
combination of these points and breaklines with the 
original DTM data eventually produces more 
accurate and high fidelity earth surface 
representation. This paper also describes on the 
process of a generating the DTM and the land 
7 
suitability identification. Finally, some results and 
discussion are provided. 
DTM DATA STRUCTURES 
DTM may be generated from various forms of data 
structure, among the prominent structures are: grid, 
contour, random, and triangular irregular network 
(TIN). A brief description of each data structure is 
provided for in this section. 
Grid 
It is the most simplest structure. The points were 
arranged in a uniform (regular) or irregular pattern. 
The square grid is the most common structure. The 
separation in x (i.e. easting) and y (i.e. northing) are 
usually at equal distance. Intersection points or grid 
points indicated with x, y, and z (height) coordinates. 
The z (height) coordinate could be a measured or an 
interpolated point. This structure has several 
advantages, for instance the neighboring point is 
implicitly defined, meaning, the location of a 
particular height is simply defined by its x and y 
position, i.e. the topology of the point is implicitly 
defined. The disadvantage of this structure is that it 
is not tailored to the terrain roughness. 
Traditionally, most of the DTM data were stored in 
this form, this is mainly due to the way they were 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B4. Vienna 1996