Web Coverage Service Developer Guide Cloud Services | August 2013 Web Coverage Service Developer Guide | 2 Table of Contents List of Figures .................................................................................................................................. 3 List of Tables ................................................................................................................................... 4 1 Introduction ................................................................................................................................ 5 1.1 About This Document ............................................................................................................ 5 1.2 Targeted Audience ................................................................................................................ 5 1.3 What is WCS? ....................................................................................................................... 5 1.4 References ............................................................................................................................ 5 2 Open Geospatial Consortium (OGC) ......................................................................................... 6 2.1 About OGC ............................................................................................................................ 6 2.2 The OGC Process ................................................................................................................. 6 2.3 OGC Standards and Specification ......................................................................................... 6 2.4 OGC Standards ..................................................................................................................... 7 2.5 Abstract Specification ............................................................................................................ 7 2.6 OGC Reference Model (ORM) ............................................................................................... 7 3 Geography Markup Language (GML)......................................................................................... 8 3.1 Introduction to GML ............................................................................................................... 8 3.2 Overview of GML Schema ..................................................................................................... 8 3.3 GML Schema Features .......................................................................................................... 9 3.3.1 AbstractFeatureType ................................................................................................................ 9 3.3.2 AbstractFeature ........................................................................................................................ 9 3.4 Overview ............................................................................................................................. 10 3.4.1 Dictionary Schema .................................................................................................................. 10 3.5 GML-Based Request ........................................................................................................... 14 4 Web Coverage Service (WCS) .................................................................................................. 16 4.1 Introduction ......................................................................................................................... 16 4.2 Service Details .................................................................................................................... 16 4.3 WCS Client Server Architecture ........................................................................................... 17 4.4 WCS Service Details ........................................................................................................... 17 4.4.1 GetCapabilities Operation ....................................................................................................... 17 4.4.2 DescribeCoverage Operation .................................................................................................. 18 4.4.3 GetCoverage Operation .......................................................................................................... 18 4.5 Basic Service Elements ....................................................................................................... 20 4.5.1 HTTP Request ........................................................................................................................ 20 4.6 Output Formats ................................................................................................................... 22 4.7 Request Parameters ............................................................................................................ 22 4.7.1 Base URL ............................................................................................................................... 22 4.8 Integration Procedure .......................................................................................................... 24 4.9 Service Exceptions .............................................................................................................. 28 4.10 WCS Layers ........................................................................................................................ 29 4.11 API Reference ..................................................................................................................... 29 Glossary ......................................................................................................................................... 32 Index 33 WEB COVERAGE SERVICE – DEVELOPER GUIDE Copyright © 2013 DigitalGlobe Inc. Proprietary & Confidential Web Coverage Service Developer Guide | 3 List of Figures Figure 4.1 A Typical Structure of a DGCS-WCS Application .................................................................................. 16 Figure 4.2 Sample WCS Client Server Application ................................................................................................ 17 Figure 4.3 Sample HTTP Post Request ................................................................................................................ 21 Figure 4.4 Pictorial Representation of Bounding .................................................................................................... 24 WEB COVERAGE SERVICE – DEVELOPER GUIDE Copyright © 2013 DigitalGlobe Inc. Proprietary & Confidential Web Coverage Service Developer Guide | 4 List of Tables Table 2.1 OGC Document Types ............................................................................................................................ 6 Table 4.1 The Parameters of a DescribeCoverage Request .................................................................................. 18 Table 4.2 GetCoverage Request Parameters ........................................................................................................ 19 Table 4.3 A General Get Request ......................................................................................................................... 20 Table 4.4 Reserved Characters in HTTP GET Query ............................................................................................ 20 Table 4.5 Values for outputFormat Attribute .......................................................................................................... 22 Table 4.6 Understanding URL parameters for GetCapabilties request.................................................................... 25 Table 4.7 Understanding URL parameters for DescribeCoverage Request ............................................................ 28 Table 4.8 WCS Layers ......................................................................................................................................... 29 Table 4.9 WCS GetCapabilities Request Parameters ............................................................................................ 29 Table 4.10 GetCoverage Request Parameters ...................................................................................................... 30 Table 4.11 DescribeCoverage Request Parameters .............................................................................................. 30 WEB COVERAGE SERVICE – DEVELOPER GUIDE Copyright © 2013 DigitalGlobe Inc. Proprietary & Confidential Web Coverage Service Developer Guide | 5 1 Introduction 1.1 About This Document This document covers the concepts of Web Coverage Service (WCS), Open Geospatial Consortium (OGC) standards for WCS, capabilities of WCS and ways to integrate DigitalGlobe Cloud Services (DGCS)-WCS in GIS- based custom application development. 1.2 Targeted Audience This document is designed to help developers of GIS-based custom application development. Developers new to WCS can read about the DGCS-WCS framework, capabilities, integration procedures and development best- practices to design methods for creating innovative world-class GIS applications. 1.3 What is WCS? DigitalGlobe’s WCS provides an interface for users to access WCS via web browsers. The current implementation includes a license file that is coded into the imagery. OGC-compliant WCS-clients can strip the license file away and display the imagery correctly. However, images downloaded directly out of WCS via a web browser will not be displayed in GIS tools. The basic WCS allows