# Presentation: 520202

## SDTS and CSDGM

**SDTS and CSDGM**

**Spatial Data Transfer Standard**
**CSDGM**** = ****(aka FGDC Metadata Standard)**

_**C**_**ontent**
**  **_**S**_**tandards for**
**       **_**D**_**igital**
**            **_**G**_**eospatial**
**                **_**M**_**etadata**

## Topics to be Covered

**Topics to be Covered**

**Intro to the CSDGM**
**What is metadata?**
**What kinds of metadata**
**Issues of using SDTS & CSDGM together**
**Implementaion Scenarios**

## What Are Metadata?

**What Are Metadata?**

**"Data about data"**
**Metadata describe the content, quality, condition, and other characteristics of data.**

**FGDC Metadata Standard**

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## What Good Are Metadata?

**What Good Are Metadata?**

**Organize and maintain an organization's internal investment in geospatial data.**
**(Do you know what you've got?)**
**Provide information about an organization's data to catalogues and clearinghouses.**
**(Can you describe to someone else what you've got?)**
**Provide information during a data transfer.**
**(Can they figure out what you've done?)**

**FGDC Metadata Standard**

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## Content Standards for Digital Geospatial Metadata

***Content Standards for Digital Geospatial Metadata***

**Identification**
**Information**

**Data**
**Quality**
**Information**

**Spatial**
**Data**
**Organization**
**Information**

**Spatial**
**Reference**
**Information**

**Entity**
**and**
**Attribute**
**Information**

**Metadata**
**Reference**
**Information**

**4**

**5**

**2**

**6**

**7**

**3**

**1**

**Distribution**
**Information**

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## Examples of Metadata

**Identification**
**Title? Area covered? Themes? Currentness? Restrictions?**
**Data Quality**
**Accuracy? Completeness? Logical Consistency? Lineage?**
**Spatial Data Organization**
**Indirect? Vector? Raster? Type of elements? Number?**
**Spatial Reference**
**Projection? Grid system? Datum? Coordinate system?**
**Entity and Attribute Information**
**Features? Attributes? Attribute values?**
**Distribution**
**Distributor? Formats? Media? Online? Price?**
**Metadata Reference**
**Metadata currentness? Responsible party?**

**FGDCMeta-##**

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Metadata describe different aspect of data, including:

Identification -- What is the name of the data set?  Who developed the data set?  What geographic area does it cover?  What themes of information does it include?  How current are the data?  Are there restrictions on accessing or using the data?
Data Quality -- How good are the data?  Is information available that allows a user to decide if the data are suitable for his or her purpose?  What is the positional and attribute accuracy?  Are the data complete?  Were the consistency of the data verified?  What data were used to create the data set, and what processes were applied to these sources?
Spatial Data Organization -- What  spatial data model was used to encode the spatial data?  How many spatial objects are there?  Are methods other than coordinates, such as street addresses, used to encode locations?
Spatial Reference -- Are coordinate locations encoded using longitude and latitude?  Is a map projection or grid system, such as the State Plane Coordinate System, used?  What horizontal and vertical datums are used?  What parameters should be used to convert the data to another coordinate system?
Entity and Attribute Information -- What geographic information (roads, houses, elevation, temperature, etc.) is included?  How is this information encoded?  Were codes used?  What do the codes mean?
Distribution -- From whom can I obtain the data?  What formats are available?  What media are available?  Are the data available online?  What is the price of the data?
Metadata Reference -- When were the metadata compiled?  By whom?

## CSDGM Document

**CSDGM Document**

**Standard uses a grammar to describe the elements**
**Elements are hierarchical and nested; compound elements**
**Definition and domain for each element**
**Mandatory; conditional mandatory; optional**

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## Example of a CSDGM Section

**Identification Information -- basic information about the data set.**
**Type:  compound**
**Identification_Information =**
**Citation +**
**Description+**
**Time_Period_of_Content +**
**Status + . . .**
**1.1  Citation -- information to be used to reference the data set.**
**Type:  compound**
**1.2  Description -- a characterization of the data set, including its intended use and limitations.**
**Type:  compound**

**Production Rule**

**Definition**

**FGDCMeta-##**

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In the standard, sections are organized in three parts:  section definition, production rules, and list of component elements.

The section definition includes the name and definition of the section.

The production rules describe the section in terms of lower-level component elements. Each production rule has an identifier (left side) and an expression (right side) connected by the symbol “=“, meaning that the term on the left side is replaced by or produces the term on the right side.  By making substitutions using matching terms in the production rules, one can explain higher-level concepts using data elements.  In addition to specifying the composition of higher-level elements, the production rules specify the elements that are mandatory and that can be repeated. 

The production rules are provided using the syntax developed by Yourdon.  The introduction to the standard describes the syntax and provides examples.

Each section is composed of data elements, either directly or through the use of intermediate elements.  The composition of intermediate elements also is provided in the production rules.

The list of component elements provides the name and definition of each component element in the section, and information about values to be provided for data elements.

## SDTS with CSDGM 

**SDTS with CSDGM **

**The CSDGM does not require any specific data set transfer format.**
**The SDTS is a way of transfering the actual data set along with its supporting metadata.**
**The CSDGM and SDTS can be used in conjunction.**

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## Comparison

**Comparison**

- ORIGINS
- CONTAINS
-           PURPOSE
- LEVELS
- NSDI
- STAND. ORG.
- USES

**SDTS**

- Ancestor of FGDC (1982)
- Defines min. content; allows user-defined
- Transfer of Data + Metadata
- Conceptual,Logical,Format
- Transfer Format
- FIPS, ANSI
- One possible format in which to receive a dataset

**CSDGM**

- FGDC (1993)
- Defines Content
-                                          Description
- Conceptual - Grammar, Elements
- Metadata Content
- ad-hoc (FGDC)
- Use the metadata to decide if you want  to obtain the dataset

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## Issues of Using CSDGM and SDTS

**Issues of Using CSDGM and SDTS**

**Which metadata elements belong in a transfer?**
**How much of the nesting and hierarchy of the metadata elements should be preserved?**
**What unit is a data set?**

## Mapping into SDTS

**Mapping into SDTS**

***Do all categories of metadata need to be preserved in a data transfer?***
**    ****No. The metadata serves different roles. The data elements serving availability and access roles, exclusively, do not belong in an SDTS data  transfer.  Some, however, are appropriate (for data quality assessment) in an SDTS lineage report.**

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## Mapping into SDTS

**Mapping into SDTS**

***The CSDGM has data elements and compound elements. Should we preserve the hierarchical nested relationships among elements?***
** ****Should preserve the information. When the structure is an inherent part of the information, then it should be preserved.  In SDTS there are many levels of aggregation---transfer, module, record, field, and subfield. The mapping needs to consider all these levels and how they relate to the CSDGM hierarchy of elements.**

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## CSDGM crosswalk to SDTS

**CSDGM crosswalk to SDTS**

**CSDGM**

- Identification
- Spatial Data Organization
- Entity&Attribute Information
- Data Quality Information
- Spatial Reference Information
- Distribution Information
- Metadata Reference Information

**SDTS**

- Identification & Other Global Modules
- Implied by use of SDTS Spatial objects
- Data Dictionary
- Data Quality Report
- Reference System Modules
- Not Applicable
- Lineage and Some Not Applicable

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## “Not a Perfect Fit”

**“****Not a Perfect Fit”**

**There are some disconnects between SDTS and the CSDGM concepts**
**However, ANSI draft of SDTS can be modified to fix these.**
**Spatial Reference Indirectly and Polar**
**SDTS uses rectangular,  spatial coordinates**
**Permits Attribute Hierarchies**
**need to convert to SDTS model**
**Altitude & Depth Encoding**
**changed ANSI draft SDTS to better support this**
**Requires Projection Parms**
**not needed for UTM/UPS and SPCS**

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## “Not a Perfect Fit”

**“****Not a Perfect Fit”**

**What is a Dataset?**
**A metadata entry could describe a series of products.**
**One entry may correspond to one, many, or part of an SDTS Transfers.**

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## Implementing Both: Case 1 

**Implementing Both: Case 1 **

**Encoding**
**Software**

**SDTS**
**Transfer**

**Produce Both Transfers and Metadata entries at same time**

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## Implementing Both: Case 2

**Implementing Both: Case 2**

**Encoding**
**Software**

**SDTS**
**Transfer**

**Produce Transfer first, then generate metadata entries later.**

**Software**

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## Implementing Both: Case 3

**Implementing Both: Case 3**

**Software**

**SDTS**
**Transfer**

**Produce Metadata entries first, then produce Transfers later.**

**Encoding**
**Software**

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## Using SDTS & CSDGM

**Using SDTS & CSDGM**

**Your SDTS Model Mapping Document should address how CSDGM elements will be mapped**
**A Standardized Way of doing this?**
**GIS Vendors are interested because both require software tools**

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