Standards and the US National Spatial Data Infrastructure

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Standards and the US National Spatial Data
Infrastructure

• Improving access to geospatial information

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Overview

• FGDC and GIS Standards
• Division of labor in standardization

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FGDC Objectives

• To promote access to and usage of digital
  geospatial information of national and local
  value
• To improve discovery of and public access to
  federal geospatial data resources
• To reduce duplication of effort among public
  sector organizations developing geospatial data

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FGDC and Standards

• FGDC provides a public forum for the development
  of content-based standards for general or
  information community use
• Examples
• Content standard for digital geospatial metadata
• Framework data standards

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Endorsement of External Standards

• In 2010, the FGDC endorsed a set of 64 external
  geospatial standards as a reference set for
  community use
• Derived from a much longer list of DoD IT
  Standards Registry (DISR)
• Point of collaboration with the
  Geospatial-Intelligence Standards Working Group
  (GWG)

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ISO Standards (TC 211)

• FGDC participates in ANSI/ISO standardization
  under ISO TC-211
• Some areas of participation
• Metadata content standard
• Services
• Encoding
• Data Quality

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FGDC and OGC

• FGDC participates in the Open Geospatial
  Consortium for the development of common
  implementation specifications to improve access
  to spatial information
• Users benefit from vendor support of information
  access specifications and integration of
  solutions into GIS workflow

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OGC Specifications

• Designing implementation solutions for discovery
  through Catalog Services
• Approved Simple Features SQL, KML, Web Map
  Server Specification, Geography Markup Language
  (GML), Catalog Services Specification, Web
  Coverage Services, Web Feature Services, Sensor
  Observation Service
• Going beyond Simple Features to raster (coverage)
  services and eventually distributed GIS

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GIS Standards Turf

• ISO TC-211 is focused on the abstract
  specifications, design framework and
  international political consensus (what)
• National standards support the development of
  community content standards (who, why)
• OGC specializes in extending the abstract model
  into implementation specifications (how)

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SDIs and Standards Advocacy
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stores service info
Metadata
UI
UI
UI
UI
managed through
managed through
are derived for each
managed through
Metadata DB/Index
Data Catalog Service
Service Registry/ Catalog
Metadata
enter/update
is exposed to the Internet through a
are loaded to or stored in
synchronize
API
queries
performs lookup to grab operation signatures
may reference instances
may be coupled to or integrated with
are derived from
API
is exposed to the Internet through a
Catalog Client
may send data to
GEOdata Access Service
feeds server info to
Spatial Data
Data/File Management System
makes maps from
stored in
distributes to and collates from multiple
Web Mapping Service
draws layers from
API
API
enhances query with
managed through
Gazetteer
API
Gateway
UI
enhances query with
Other Service
API
Thesaurus
provides application access through
1
2
3
Symbols
current
Software/Service
planned
1. builds query screens for 2. submits
queries/requests to 3. returns search responses
UI
API
Information
SDI Interaction Diagram revised
7-May-2003 ddnebert_at_fgdc.gov
interacts with
interacts with
Interface
UI
API
Web Client
Application Client
Function
now
planned.
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Standards are monolithic yet interdependent
WFS 1.0
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Framework Themes

• Themes providing the core, most commonly used set
  of base data are known as Framework Data
• Geodetic Control,
• Orthoimagery,
• Elevation and Bathymetry,
• Transportation,
• Hydrography,
• Cadastral, and
• Governmental Units.

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Additional Data

• Geographic names (toponymy) layer
• Land cover/vegetation/wetlands
• Cultural and Demographic Statistics
• Buildings and Facilities
• Natural hazards
• Soils and Geology
• Utility distribution networks

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Framework Standards

• In 2008, the FGDC published eleven Framework
  standards
• Included an abstract model (in UML) and had
  companion XML schema files

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Design Process
4. Comments
5. Refine
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Conceptual Model

• A conceptual or logical design of the information
  that preserves the native groupings of the data
• Is implementation- and software-independent to
  provide a stable base for current and future
  implementations
• Describes graphically and with narrative the
  design assumptions and conditions
• Currently expressed using the Unified Modeling
  Language (UML)

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What is UML?

• Unified Modeling Language
• UML is an industry standard language for
  visualizing, specifying, constructing, and
  documenting artifacts of a software-intensive
  system
• Platform-neutral environment for abstract
  modeling of data and processes
• Adopted as the Conceptual Schema Language for ISO
  TC 211

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UML Diagrams
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Class Diagram

• Captures the vocabulary of a system
• Built and refined throughout development
• Purpose
• Name and model concepts in the system
• Specify collaborations
• Specify logical database schemas
• Developed by analysts, designers, and implementers

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UML Class Diagram
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The UML

• Useful for diagramming systems, objects, and
  relationships
• Many diagrammatic conventions
• Many ways to diagram the same thing
• Can serialize the UML as XML (XMI)
• CASE tools or transforming programs can create
  implementation bindings
• FGDC is hosting a UML-to-GML transform program
  for convert UML into XML Schema

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UML per Rational Rose
Implementations
Oracle Table Schema
Conceptual Models
User Interface
content
Java Program Code
Integrated Development Environment
UML
procedures and structures
r u l e s
structures
XML Schema Document
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Start Modeling

• Review existing models from FGDC and The National
  Map efforts and adapt/adopt them if possible
• Identify theme experts who are either producers
  or users of digital geographic data
• Apply modeling expertise to work with the experts
  interactively to build model

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Framework Data Modeling

• Based on provider and consumer requirements for
  GIS and mapping, focus on a specific theme of
  information
• Convened a group of experts with modeling support
  and have them bring any relevant systems designs
  or requirements documents
• Built models that support a common, not
  universal, set of needs
• Publish model and narrative in a standard

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Common Modeling Baseline

• Feature types (classes) included
• Unique feature identifier system
• Basic attributes
• Controlled vocabulary, codes, authorities
• Valid at a range of scales and resolutions
• Multiple representations of same features possible

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Feature Catalog

• One first step toward developing a conceptual
  model of geographic information is to construct a
  Feature Catalog
• Feature Catalog includes
• Feature types, definitions
• Attributes, definitions, data types
• Domains, expected values and types

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Catalog as Abstract Model

• Feature Catalog describes what information is
  included in a given data theme and what
  properties and values are stored there
• A feature catalog is not an implementation model
  but can, with rules, be used to create one or
  more implementation models
• Implementation guidance supplements abstract or
  conceptual models

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Example UML Model(example excerpt from the hydro
model, prior to face-to-face session in November)
Dataset
describedBy
Metadata is at a
Metadata
collection level for
Time of sample
example it will apply t
POC
o ISO, FGDC etc.
etc.
HydroLine
HydroArea
HydroPoint
Reach ID
Elevation of area
ReachID
From position
Water surface basis height
Periodicity Periodicity Type Enumeration
To Position
Area of feature
Cartographic feature type code
Length
Region ID
Hydrographic feature code
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Example Tabular Description
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Going from the Abstract to Implementation

• Conceptual modeling yields the natural
  organization of the data but not a specific
  implementation
• For interoperability in the exchange of data, an
  agreement on encoding and format is required
• CASE tools and scripts can convert UML designs
  into specific implementation schemas

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Application Schema

• Name for the rules that define the content,
  relationships, attributes, domain values and
  constraints in a specific implementation
  environment
• UML may be converted into XMI to load the model
  design into a different modeling software
• UML may be converted to an XML/GML Schema
  Document

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Content Format
validation
Conceptual Data Model
Implementation model/schema for Format A
Format A
Data
encoding
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Creating a Standard
Data Content and Exchange Standard
Conceptual Data Model
Narrative with context, obligation, examples
Implementation Schemas

• A standard facilitates interoperability if it
  includes both the conceptual data model and one
  or more implementation annexes with specific
  guidance for content validation

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Framework Standard Outline

• Introduction
• Scope and Context
• Data Content Model in UML
• Descriptive table and narrative
• Annex Encoding using XML (GML 3.0)

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Geospatial Services

• Increasingly geospatial data can be accessed in
  real-time over local area networks and the
  Internet as if it were local data
• Multiple organizations can benefit from the data
  being staged and maintained once and used many
  times
• Desktop software and portals can use these
  services over the Web

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Flow of Standard Data
Conceptual Data Model
UML
Database creation script
Data conversion script
SQL
XSLT
Web Feature Server
request
Data
adapter
Client
XML
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Framework Interoperability Pilot for
Transportation

• OpenGIS Consortium (OGC) is assisting in modeling
  process to define proper UML that conforms to ISO
  rules and can be implemented as GML
• Contract with OGC members to implement Web
  Feature Services to extend multiple available
  data systems (U.S. and Canada)
• Implement a Web client that can display and query
  multiple Framework data sources based on the
  common data model
• Approach to be followed for other themes

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Establish WFS on agreed content nationwide
WFS
Mission System A
Web Feature Browser/ Client Application
translation utilities
GML (XML)
Native Format
Mission System B
WFS
B
private schema
P
public schema
transformation rules
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http//www.fgdc.gov

• Doug Nebert
• ddnebert_at_usgs.gov