日志
GDF读书笔记
专业类日记 2009-07-28 22:16:30 阅读20 评论2 字号：大中小
本笔记是本人毕业进入导航业第一个月（2008年8月份），在我很敬仰的引导人吩咐下，苦读GDF4.0英文版写下的。现在共享出来，该笔记适用于刚进入导航业的人或是想入手学习GDF的人。该笔记能让大家对GDF有个整体上的了解，如还需深入学习，就得靠自己慢慢研究。参考资料：GDF 4.0-140201
一、GDF概述
GDF，全称Geographical Da
二、 GDF内容
GDF的主要内容如下图：
因此，根据GDF主旨和内容的编排，主要讲述了特征要素分类和定义、要素的属性及其值域、要素关系类型及定义和要素的表达规则。根据此特点和自己看文档的顺序，也将读书笔记整理为四个内容。
三、特征要素的分类和定义（Feature Catalogue）
纵观GDF的要素分类和定义，总共分了12个要素主题，然后以要素主题出发，每个要素主题分出若干要素类或要素。详细情况如下：
1. 道路与渡口（Roads and Ferries）
要素主题：
Roads and Ferries
根据应用需求其子类共12类按level 1和level 2进行表达。所以该要素主题的要素类如下：
Level 1描述的为简单要素：
Road Element
Junction
Ferry Connection
Enclosed Traffic Closed
Address Area Boundary Element
Address Area
Level 2描述的为复杂要素：
Road
Intersection
Ferry
Aggregated Way
Interchange
Roundabout
2. 行政区划（Administrative Areas）
要素主题：Administrative Areas
此要素主题包括的要素类或要素共39类，分别为：
Administrative Boundary Element
Administrative Boundary Junction
Administrative Place A to Z
Country
Order-1 to 7 Areas
Order-8 Area
Order-9 Area
Supra-National Area
3. 命名区域（Named Areas）
Named Areas是具有独立功能或作用的区域。
要素主题：Named Areas
此要素主题包括要素种类或要素共12种，如下：
Boundary Element
Boundary Junction
Built-up Area
Census District
Elective District
Emergency Medical Dispatch District
Fire Dispatch District
Named Area
Phone Disrtict
Police District
Postal District
School District
4. 土地覆盖和土地利用（Land Cover And Use）
要素主题：Land Cover And Use
Land Cover And Use类型在结构上是层次化的，其要素类可再深入划分子类。因此，其要素类和各个要素类的子类情况如下：
Building
Artificial Surface
Urban Fabric
Continuous Urban Fabric
Discontinuous Urban Fabric
Industrial, Commercial And Transport Unit
Industrial Or Commercial Unit
Road And Rail Networks and Associated Land
Port Area
Airport
Mine, Dump And Construction Site
Mineral Extraction Site
Dump Site
Construction Site
Artificial, Non-Agricultural Vegetated Area
Green Urban Area
Sport And Leisure Facility
Agricultural Areas
Arable Land（耕地）
Non-Irrigated Arable Land
Permanently Irrigated Land
Rice Field
Permanently Crop
Vineyard（葡萄园）
Fruit Trees And Berry Plantation
Olive Grove（油橄榄幼林）
Pasture And Rangeland
Pasture（牧草）
Rangeland（草地）
Heterogeneous Agricultural Area
Annual Crops Associated With Permanent Crop
Complex Cultivation Pattern
Land Principally Occupied By Agriculture, With Significant Area Of Natural Vegetation
Agro-Forestry Area（混合林业区）
Forest And Semi-Natural Area
Forest
Broad-Leaved Forest
Coniferous Forest（针叶林）
Mixed Forest
Shrub And/Or Herbaceous Vegetation Associations
Natural Grassland
Moore And Healthland
Sclerophyllous Vegetation（硬叶植被）
Traditional Woodland/Shrub
Open Space With Little Or No Vegetation
Beach, Dune And Sand Plain
Bare Rock
Sparsely Vegetated Area
Burnt Area
Glacier And Perpetual Snow
Wetlands
Inland Wetland
Inland Marsh
Peatbog（泥炭沼泽）
Forested Wetland
Coastal Wetland
Salt Marsh
Saline
Intertidal Flat
Island
5. 结构设施（Structure）
Structures是交通网络中的重要建筑物。
一个结构设施要素可以根据结构设施类型属性来分类。
6. 铁路（Railways）
Railways在网络构成方式上与道路相似。因此，Railways也是由Railway Element 和Railway Element Junction构成。
7.水系（Waterways）
要素主题：Waterways
此要素主题包括的要素类或要素共有13类，分别为：
Canal
Coastal Lagoon（海岸泻潮）
Estuary
Inland Water
Lake
Marine Water
Reservoir
Sea And Ocean
Water Body
Water Boundary Element
Water Boundary Junction
Water Course
8. 道路附属设施（Road Furniture）
要素主题：Road Furniture
此要素主题包括的要素类或要素共有9类，分别为：
Environmental Equipment
Signpost
Traffic Light
Traffic Sign
Lighting
Measurement Device
Road Markings
Safety Equipment
Pedestrain Crossing
9.服务（Services）
Service的定义和分类是对于现实的解释而不是对其的表达。
要素主题：Services
通用要素类：Entry Point Of Service
10.公共交通（Public Transport）
要素主题：Public Transport
该要素主题包括的要素子类有7个，如下：
Line
Public Transort Juction
Public Transport Point
Route
Route Link
Stop Area
Stop Point
11. 链参照要素（Chainage Referencing Features）
要素主题：Chainage Referenceing Features
此要素主题包括的要素有2个，如下：
Chainage Referencing Section
Reference Point
12. 通用要素（General Features）
General Features其性质、属性及关系适合于所有要素主题的要素。其数据模型中包括了两个要素：Centre Point Of Feature 和Traffic Location
四、要素的属性及其值域（Attribute Catalogue）
现实世界对象的性质表现是通过属性来表示的。其中属性的每一个属性类型都与对象的一个性质相对应。
GDF 中的属性数据模型图：
在GDF中除了General Feature与Railways没有定义属性数据模型外，其余10个要素主题都定义了相应的属性数据模型。分别如下：
The da
The da
The da
The da
The da
The da
The da
The da
The da
The da
The da
五、 要素关系类型及定义（Relationship Catalogue）
现实世界的对象不是独立的，对象与对象之间存在与之相对应的关系。因此，建立要素之间的联系就需要用关系这种形式来表达。
GDF中的关系数据模型图：
在GDF中总共说明了13个关系的数据模型，51个关系类型。
13个关系分别为：
Fork Relationship Da
Toll Route Relationship Da
Manoeuvre Relationship Da
Through Route Relationship Da
Grade-separated Crossing Relationship Da
Signpost Information Relationship Da
Exit At Interchange Relationship Da
Traffic Sign Along Road Element And Traffic Light Along Road Element Relationship Da
Relationship with arity 2 Involving The Feature Themes Roads And Ferries, Administrative Areas, Named Areas, Land Cover And Use, And Services Da
Public Transport Features Relationship Da
Relationship involving the Feature Themes Roads and Ferries and Chainage Referencing Features Da
Centre Point of Feature belonging to Feature Relationship Da
Place within Place Relationship
51个关系类型如下：
Building along Road Element
Building Associated with Administrative Area
Building Associated with Built-uo Area
Built-up Area Associated with Administrative Area
Centre Point of Feature belonging to Feature
Chainage Referencing
District Associated with Administrative Area
District Associated with Built-up Area
Divided Junction
Enclosed Traffic Area Associated with Administrative Area
Enclosed Traffic Area Associated with Built-up Area
Exit at Interchange
Ferry Connection Associated with Administrative Area
Ferry Connection Associated with Named Area
Ferry Connection Associated with Built-up Area
Fork
Grade-Separated Crossing
Junction Associated with Administrative Area
Junction Associated with Built-up Area
Place within Place
Priority Manoeuvre
Prohibited Manoeuvre
Public Transport Point along Route Link
Reference Point Location along Road Element
Restricted Manoeuvre
Road Element Associated with Administrative Area
< Associated Element>Built-up Area
Road Element Associated with District
Road Element Associated with Named Area
Road Element belonging to Service
Road Element leading to Enclosed Traffic Area
Road related Object related to Chainage Referencing Section
Road related Object related to Road Element
Route Link along Road Element
Service along Road
Service along Road Element
Service Associated with Administrative Area
Service Associiated with Built-up Area
Service Associated with Named Area
Service at Interchange
Service at Junction
Service related to Service
Signpost Information
Stop Point along Road Element
Stop Point along Route
Stop Point at Junction
Stop Point located near Service
Through Route
Toll Route
Traffic Light along Road Element
Traffic Sign along Road Element
六、要素表达规则（Feature Representation Rules）
Feature Representation Rules的目的是说明如何用不同的Feature categories来表示某一个要素，以及如何用cartographic primitives来表示简单要素。对于属于同一个要素类的要素其要素类型不一定相同。在GDF中，每一个要素类型可以用多种方式来表达，这就与可表达的拓扑关系有关。
GDF中的要素表达数据模型图：
Non-explicit topology
Connectivity topology
Full topology
在GDF中要素的表达层次也分为三层，分别为：
Level 0: The Geometry
Level 1: The Simple Features
Level 2: The Complex Features
根据特征要素表达成的12个要素主题，分别从其要素的表达层次进行了说明。
七、GDF总结（Summary）
通过本次的快速阅读，对GDF标准的总体结构有了一定的了解，大概如下：
1.GDF定义的特征要素很多，但不是所有的特征要素都能放在我们的以需求为驱动的导航产品中去，另外根据实际情况，还需要自定义一些特征要素。
2.GDF对要素属性的定义也非常全面，例如在对道路的属性编码中，就定义了高达20多项。
3.GDF对要素之间的关系通过关系模型定义得很清楚，如一个关系Service Associated with Buit-up Area，从关系中我们就可以得到此关系所涉及的要素为：Service和Built-up Area。
4. 在GDF附录中，提供了对数据质量的标准和依据，这有助于在数据生产过程中的质量控制有据可循。
有0人推荐
评论