An enhanced approach for surface flow routing over drainage-constrained triangulated irregular networks

2017 ◽  
Vol 22 (1) ◽  
pp. 43-57 ◽  
Author(s):  
Fangli Zhang ◽  
Qiming Zhou ◽  
Qingquan Li ◽  
Guofeng Wu ◽  
Jun Liu
Keyword(s):  
Surface Flow ◽  
Flow Routing ◽  
Triangulated Irregular Networks ◽  
Irregular Networks

scholarly journals FAST ROBUST ARITHMETICS FOR GEOMETRIC ALGORITHMS AND APPLICATIONS TO GIS

2021 ◽  
Vol XLVI-4/W2-2021 ◽  
pp. 1-8
Author(s):  
T. Bartels ◽  
V. Fisikopoulos
Keyword(s):  
Code Generation ◽  
Computational Cost ◽  
Floating Point ◽  
Data Sets ◽  
Delaunay Triangulations ◽  
Triangulated Irregular Networks ◽  
Gis Data ◽  
Irregular Networks ◽  
Meta Programming ◽  
Point Arithmetic

Abstract. Geometric predicates are used in many GIS algorithms, such as the construction of Delaunay Triangulations for Triangulated Irregular Networks (TIN) or geospatial predicates. With floating-point arithmetic, these computations can incur roundoff errors that may lead to incorrect results and inconsistencies, causing computations to fail. This issue has been addressed using a combination of exact arithmetics for robustness and floating-point filters to mitigate the computational cost of exact computations. The implementation of exact computations and floating-point filters can be a difficult task, and code generation tools have been proposed to address this. We present a new C++ meta-programming framework for the generation of fast, robust predicates for arbitrary geometric predicates based on polynomial expressions. We show examples of how this approach produces correct results for GIS data sets that could lead to incorrect predicate results for naive implementations. We also show benchmark results that demonstrate that our implementation can compete with state-of-the-art solutions.

scholarly journals A Modified Methodology for Generating Indoor Navigation Models

2019 ◽  
Vol 8 (2) ◽  
pp. 60 ◽  
Author(s):  
Elżbieta Lewandowicz ◽  
Przemysław Lisowski ◽  
Paweł Flisek
Keyword(s):  
Spatial Data ◽  
Medial Axis ◽  
Indoor Navigation ◽  
Medial Axis Transformation ◽  
Triangulated Irregular Networks ◽  
Modeled Structure ◽  
Irregular Networks ◽  
Thiessen Polygons ◽  
Automatic Methods ◽  
Traditional Approaches

Automatic methods for constructing navigation routes do not fully meet all requirements. The aim of this study was to modify the methodology for generating indoor navigation models based on the Medial Axis Transformation (MAT) algorithm. The simplified method for generating corridor axes relies on the Node-Relation Structure (NRS) methodology. The axis of the modeled structure (corridor) is then determined based on the points of the middle lines intersecting the structure (polygon). The proposed solution involves a modified approach to the segmentation of corridor space. Traditional approaches rely on algorithms for generating Triangulated Irregular Networks (TINs) by Delaunay triangulation or algorithms for generating Thiessen polygons known as Voronoi diagrams (VDs). In this study, both algorithms were used in the segmentation process. The edges of TINs intersected structures. Selected midpoints on TIN edges, which were located in the central part of the structure, were used to generate VDs. Corridor structures were segmented by polygon VDs. The identifiers or structure nodes were the midpoints on the TIN edges rather than the calculated centroids. The generated routes were not zigzag lines, and they approximated natural paths. The main advantage of the proposed solution is its simplicity, which can be attributed to the use of standard tools for processing spatial data in a geographic information system.

An object-oriented framework for distributed hydrologic and geomorphic modeling using triangulated irregular networks

2001 ◽  
Vol 27 (8) ◽  
pp. 959-973 ◽  
Author(s):  
Gregory E. Tucker ◽  
Stephen T. Lancaster ◽  
Nicole M. Gasparini ◽  
Rafael L. Bras ◽  
Scott M. Rybarczyk
Keyword(s):  
Object Oriented ◽  
Triangulated Irregular Networks ◽  
Irregular Networks
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