Izham Mohamad Yusoff

The hierarchical three-dimensional (3D) dynamic water infiltration on multi-layers of soil according to Voronoi sequence nodes based on the three-dimensional triangular irregular network (3D TIN)

Understanding soil water infiltration movement has been birthed from extensive interest and concern in the last few decades. The arrangement of particles (i.e. structures and sizes) and the interaction between both the soil and soil water have a profound effect on the soil water infiltration. The challenging task in the soil fluid modelling is the indeterminate spatial extent that has no specific boundaries and the fact that it is difficult to sense. Plenty of investigations and studies have been conducted to measure the water movement. However, less focus has been given on the movement of the dynamic soil water infiltration. This paper will focus on modelling the three-dimensional (3D) soil water infiltrations that flow downward due to the gravitational factor and gradient pressure. The 3D hierarchical soil water infiltration model proposes the integration of techniques which includes the Tree-map to isolate the depth of the soil that acts as a route of the soil water flow from the surface of the terrain to the subsurface flow. Moreover, the 3D Gosper curve is used to represent the soil water flow pattern that is based on the law of gravity and Horton equation, which control the flow of the soil water in the model. The curves that consist of a series of nodes adopt the Three-Dimensional Triangular Irregular Network (3D TIN) which creates a network of flow direction that allows the water to pass through the nodes according to a predetermined sequence. The study area has an average of 8.5 mm total rain and −5 m water level. The soil is divided into a few layers to represent the flow of the soil water according to the sequence of nodes. The soil depth (40, 80, 120, 160 and 200 cm) isolation in the form of Voronoi-shaped polygon nodes allows the soil water to flow down where the depth is chosen based on the soil wetting range of the subsurface soil.

Highly Efficient Computer Oriented Octree Data Structure and Neighbours Search in 3D GIS

Three-dimensional (3D) visualization has given a new perspective in various fields such as urban planning, hydrology, infrastructure modelling and geology. This is due to its capability of handling real world object in more realistic manners, rather than the two-dimensional (2D) approach. However, implementation of 3D spatial analysis in the real world situations has proven to be difficult to comprehend due to the complexity of the algorithm, computational process and time consuming. The existing Geographical Information Systems (GIS) enable 2D and two-and-a-half-dimensional (2.5D) spatial datasets, but less capable of supporting 3D data structures. Recent development in Octree showed that more effort was given to improve the weakness of Octree in finding neighbouring nodes by using various address encoding scheme with specific rule like matrix, lookup table and arithmetic to eliminate the need of tree traversal. Therefore, the purpose of this paper is to propose a new method to speed up the neighbouring search by eliminating the needs of complex operation to extract spatial information from Octree by preserving 3D spatial information directly from the Octree data structure. This new method will be able to achieve O(1) complexity and utilizing Bit Manipulation Instruction 2 (BMI2) to speed up address encoding, extraction and voxel search 1000x compared to generic implementation.

A comparative study of frequency ratio, statistical index and poisson method for landslide hazard mapping along East-West highway

The purpose of this study is to evaluate of the landslide hazard along East-west Highway (Gerik- Jeli) using frequency ratio, statistical index and poisson method. Historical data in this area were identified by field work in years 2007 until 2012. The factors chosen in producing of landslide hazard map were geology, rainfall, slope angle, soil texture, stream, profile curvature, plan curvature, NDVI, fault Line, elevation, age of rock and aspect. The results of the analysis for these three methods were verified using actual landslide location data. The validation results showed satisfactory agreement between the landslide hazard map and the existing data on landslide locations. The estimating of influencing factor also was carried out using sensitivity analysis.