Indexing the Sphere with the Hierarchical Triangular Mesh
نویسندگان
چکیده
We describe a method to subdivide the surface of a sphere into spherical triangles of similar, but not identical, shapes and sizes. The Hierarchical Triangular Mesh (HTM) is a quad-tree that is particularly good at supporting searches at different resolutions, from arc seconds to hemispheres. The subdivision scheme is universal, providing the basis for addressing and for fast lookups. The HTM provides the basis for an efficient geospatial indexing scheme in relational databases where the data have an inherent location on either the celestial sphere or the Earth. The HTM index is superior to cartographical methods using coordinates with singularities at the poles. We also describe a way to specify surface regions that efficiently represent spherical query areas. This article presents the algorithms used to identify the HTM triangles covering such regions.
منابع مشابه
Planetary Modelling via Hierarchical
In encoding, simplifying, amalgamating and intersecting cartographic features, it is useful to know the precision of locational data being processed. It is suggested that representing spatial phenomena in a hierarchical tessellated framework can facilitate documenting the certainty of coordinates and in dealing with its consequences. Objects thus encoded can identify the precision with which th...
متن کاملمقایسه ساختار اصطلاح نامههای پایگاههای اطلاعاتی Pubmed و Embase با استاندارد اصطلاحنامه نویسی سازمان ملی استانداردهای اطلاعاتی آمریکا و بررسی شیوههای نمایه سازی دو پایگاه
Introduction: According to mortality rates in Iran, cardiovascular diseases, neoplasms, perinatal mortality, and respiratory tract diseases were top rate mortality in 2003(1382). To reduce mortality rate, Iranian medical community need to know more about recent therapeutic regimens. Two main medical databases are Pubmed and Embase. Researching Pubmed and Embase indexing methods and comparing Me...
متن کاملTessellation of a Unit Sphere Starting with an Inscribed Convex Triangular Mesh
3 Subdivision Algorithm 3 3.1 Centroid of Polyhedron . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3.2 Intersection of Ray with Sphere . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3.3 Memory Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3.4 Pseudocode for a Single Subdivision . . . . . ...
متن کاملA Mix Global Data Structure Based on Qtm and Voronoi
To efficiently store, retrieve and update the global spatial data, a hierarchical and dynamic data model on a global scale is urgently needed. The QTM (Quaternary Triangular Mesh) as a hierarchical quadtree data structure on sphere is one of the most efficient methods for managing the global spatial data in many applications. But QTM structure is based on fields instead of objects. So it is eff...
متن کامل3D Models Recognition in Fourier Domain Using Compression of the Spherical Mesh up to the Models Surface
Representing 3D models in diverse fields have automatically paved the way of storing, indexing, classifying, and retrieving 3D objects. Classification and retrieval of 3D models demand that the 3D models represent in a way to capture the local and global shape specifications of the object. This requires establishing a 3D descriptor or signature that summarizes the pivotal shape properties of th...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- CoRR
دوره abs/cs/0701164 شماره
صفحات -
تاریخ انتشار 2005