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Section 5: Mapping of Dataset, Theme, Surface Attributes

5. Mapping of Dataset, Theme, and Surface Attributes

This section addresses the mapping of the attributes for the DLG-E objects dataset, theme, and surface. Not all DLG-E attributes map to SDTS attributes. The definition of each attribute must be examined to decide how best to map it. The options to consider are:

1. encode the attribute in a standard subfield; or

2. encode the attribute as a user-defined attribute; or

3. do not encode the attribute.

The order of Section 5 is first an enumeration of the attributes, followed by a mapping of these attributes employing the options just listed. Lastly, attribute table designs are given for the set of attributes that are to be encoded as SDTS attributes.

5.1 List of Attributes

The current set of attributes for the dataset, theme, and surface-objects are listed in the following sections. Most of the attributes come from the Standards Database (version 0.12), with a few from the DLG-E Portable Data File (DPDF of 12/92). Elements from the DPDF have "dpdf' on the left and the other attributes have their 3-character code from the Standards Database. The list are arranged in a topical order. (The mapping tables that follow in the next section are arranged in alphabetical order by the codes.)

5.1.1 Attributes of DLG-E Dataset

Following is the current list of attributes for the DLG-E dataset object, in topical order. The codes preceding the terms can be used to look up the elements in the mapping table.

dpdf    Dataset ID
dpdf    DPDF Version Number
DMN     Domain Name 
STC     State Coverage
NTC     Nation Coverage
MLT     Geographic MBR SW Corner Latitude
MLG     Geographic MBR SW Corner Longitude
SLL     Geographic MBR Latitude Span
SLG     Geographic MBR Longitude Span
MFL     Geographic MBR Filled Indicator

HCS     Horizontal Coordinate System ID
UOM     Hor. Coord. System Units of Measure
HDM     Horizontal Datum
HSG     Horizontal Coordinate System Granularity
RHD     Resolution of Horizontal Data
dpdf    General Cartographic Trans. Package (GCTP) Parms
dpdf    Hor. Coord. System Projection Zone Number
dpdf    Hor. Coord. Integer to Float (HCIF) Factor

VSG     Vertical Coordinate System Granularity
VDM     Vertical Datum
PCI     Primary Contour Interval
SCI     Secondary Contour Interval
SPC     Supplemental Contour Interval
HYM     Hypsographic Units of Measure

dpdf    DLG-E Standards Content Version Number
dpdf    Number of Surfaces

5.1.2 Attributes of DLG-E Theme

Following is the current list of attributes for the DLG-E theme object, in topical order. The codes preceding the terms can be used to look up the elements in the mapping table.

dpdf    Theme ID
dpdf    Theme Type
dpdf    Containing Surface ID
THA     Theme Activity
dpdf    Number of Feature Instances
CDT     Completion Date

SUO     Submitting Organization
PRO     Processing Organization
PSS     Processing Software System
DCH     Data Collection Hardware ID
DEH     Data Editing Hardware ID
DPH     Data Processing Hardware ID

PST     Primary Source Type
SDC     Source Description
SRT     Source Revision Type
SOR     Source Origin
PEY     Primary Map Edit Year
PIY     Primary Initial Year
PFY     Primary Final Year
REY     Revision Map Edit Year
RIY     Revision Initial Year
RFY     Revision Final Year

LRS     Lowest Resolution
HRS     Highest Resolution
SSD     Smallest Scale Denominator
LSD     Largest Scale Denominator

BAD     Bathymetric Datum
EBD     Elevation of Bathymetric Datum
PBI     Primary Bathymetric Interval
SBI     Secondary Bathymetric Interval
SPB     Supplemental Bathymetric Interval
BAU     Bathymetric Units of Measure

5.1.3 Attributes of DLG-E Surface

Following is the current list of attributes for the DLG-E surface object, in topical order. The codes preceding the terms can be used to look up the elements in the mapping table.

dpdf    Surface ID
SIA     Surface Integration Activity
dpdf    Number of Themes
CDT     Completion Date

PRO     Processing Organization
PSS     Processing Software System
DEH     Data Editing Hardware ID
DPH     Data Processing Hardware ID

5.2 Attribute Mapping

This section will describe in detail how each of the attributes for the dataset, theme, and surface objects are mapped into the SDTS. The mapping is presented in tabular form with table end notes when a more detailed description is necessary.

The format of the tables have DLG-E elements on the left and the SDTS elements on the right. The first column contains the 3-character attribute code which is used as a shorthand in identifying the attributes. The second column contains the descriptive name of the attribute. The third column contains multiple lines describing the mapping into the SDTS. The first line in the third column contains the SDTS Module, field, and subfield that are affected (identified by their mnemonics.) The second line contains the descriptive subfield name. Any additional lines discuss Conversion of values or other additional processing that is needed (references to table end notes are in parenthesis.)

5.2.1 Dataset Attribute Mapping

The following tables list all of the attributes for a DLG-E object in the left column and how they are mapped into the SDTS in the right column.

 Code   Dataset Attribute      SDTS Mod/Fld/Sub
-----   -----------------      ----------------------------------
 DMN    Domain Name            IDEN/IDEN/TITL
                               Title of the transfer.

 HCS    Horizontal             XREF/XREF/RSNM
        Coordinate System Id   Reference System Name.
                               Convert value to SDTS enumerated
                               type (3)

 HDM    Horizontal Datum       XREF/XREF/HDAT
                               Horizontal Datum.
                               Convert value to SDTS enumerated
                               type (4)
 HSG    Hor. Coor. System      ATPR/ATTP/HSG
        Granularity            user-defined attribute.

 HYM    Hypsographic Units     DDSH/DDSH/UNIT
        of Measure             Unit of an attribute.
                               Use for all records
                               describing contour interval
                               attributes: PCI, SCI, SPC

 MFL    Geographic MBR         SPDM/SPDM/COMT
        Filled Indicator       Comment.
 MLG    Geographic MBR SW      SPDM/DMSA/X
        Corner Longitude       Domain Spatial Address.
                               Convert to External System (1)

 MLT    Geographic MBR SW      SPDM/DMSA/Y
        Corner Latitude        Domain Spatial Address.
                               Convert to External System (1)

 NTC    Nation Coverage        ATPR/ATTP/NTC
                               user-defined attribute.
 PCI    Primary Contour        ATPR/ATTP/PCI
        Interval               user-defined attribute.

 RHD    Resolution of          IREF/IREF/XHRS & YHRS
        Horizontal Data        X,Y Component of Hor. Res.

 SCI    Secondary Contour      ATPR/ATTP/SCI
        Interval               user-defined attribute.

 Code   Dataset Attribute      SDTS Mod/Fld/Sub
 SLG    Geographic MBR         SPDM/DMSA/X
        Longitude Span         Domain Spatial Address.
                               Use to calculate NE (1)

 SLL    Geographic MBR         SPDM/DMSA/Y
        Latitude Span          Domain Spatial Address..
                               Use to calculate NE (1)

 SPC    Supplemental Contour   ATPR/ATTP/SPC
        Interval               user-defined attribute.
 STC    State Coverage         ATPR/ATTP/STC
                               user-defined attribute.

 UOM    Hor. Coor. System      IREF/IREF/SFAX & SFAY
        Units of Measure       Scaling Factor X,Y.
                               Indirectly used to set (2)

 VDM    Vertical Datum         ATPR/ATTP/VDM
                               user-defined attribute.

 VSG    Vert. Coor. System     ATPR/ATTP/VSG
        Granularity            user-defined attribute.
 dpdf   Dataset ID             IDEN/IDEN/DAID
                               Dataset Identifier.

 dpdf   DPDF Version Number    IDEN/IDEN/DAID
                               Dataset Identifier.
                               Concatenate this value to
                               Dataset ID with a "v" for
                               version. "1 v1.0"

 dpdf   GCTP Parms: Lat &      Not Encoded.
        Long of any point in   (derivable)
        zone
 dpdf   Horiz. Coord. System   XREF/XREF/ZONE
        Projection Zone        Projection Zone Number.
        Number^M

 dpdf   Hor. Coord. Integer    IREF/IREF/SFAX & SFAY
        to Float (HCIF)        Scaling Factor X, Y.
        Factor                 Used to set conversion from
                               internal coords to external (2)

 dpdf   DLG-E Standards        ATPR/ATTP/CONTENT_VERSION
        Content Version        user-defined attribute.
        Number

 Code   Dataset Attribute      SDTS Mod/Fld/Sub
 dpdf   Number of Surfaces     Not Encoded.
                               (derivable)

NOTES:

• (1) - Encoding Spatial Domain. SDTS supports a ring of coordinates or the SW and NE corners of the Minimum Bounding Rectangle. The coordinates must be in the internal system or external system. Geographic coordinates must be in decimal degrees.

  DLG-E has the SW corner of the MBR and the span of each side of the MBR. It also has values in Geographic coordinates, which is different from the external system (UTM) and the internal. Longitude values are negative for east of the prime meridian. Latitude values are positive north of the equator. Geographic values are in decimal degrees.

  Processing: To calculate the NE corner from the SW, add the span values. Then convert the SW and NE corner values to the external coordinate system.

• (2) - The Internal Spatial Reference Module specifies the scaling and translation factors to convert internal coordinates to an external coordinate system. The DLG-E coordinate values are actual external coordinate values, but with the decimal point moved so as to treat them as integers. To convert the DLG-E coordinates to external coordinates, divide by the HCIF Factor. To encode this scaling parameter in the IREF module, use its inverse in the SFAX and SFAY subfields.

  All X,Y coordinates must be in meters for UTM and State Plane. Internal coordinates can be left in feet, if the feet to meters conversion factor is specified in the Internal Spatial Reference as a scaling factor.

  • If "feet", then use feet to meter conversion factor of "0.3048" for X and Y scaling factor
  • If "meters", then use "1.0" for the scaling factor.

• (3) - The Horizontal Coordinate System ID value will need to be converted to an SDTS enumerated type.
  • If "Geographic" use "GEO";
  • If "State Plane" use "SPCS";
  • If "Universal Transverse Mercator" use "UTM";

  • Otherwise, error (the dataset will need to be converted to one of the above before being encoded to be compliant with the Topological Vector Profile of the SDTS. )

• (4) - The Horizontal Datum value will need to be converted to an SDTS enumerated type.
  • If "North American Datum 1927" use "NAS";
  • If "North American Datum 1983" use "NAX";
  • Otherwise, use value as is.

5.2.2 Theme Attribute Mapping

The following table lists all of the attributes of the theme object in the left column and how they are mapped into the SDTS in the right column. (The issue of whether certain attributes provide useful lineage information is still under review.)

5.2.3 Surface Attribute Mapping

The following table lists all of the attributes of the surface object in the left column and how they are mapped into the SDTS in the right column.

5.3 Attribute Table Design

Only those elements that are encoded as SDTS attributes will be placed in SDTS attribute tables. For each object, these can be located by inspecting the third column of the mapping tables in Section 5.2. Generally, each object would have one attribute table. The occurrence of multi-valued attributes or large numbers of attributes that break down by subject have caused additional attribute tables to be used.

The attribute tables used for each object are described. The table is listed as its column headings will appear. Following each table the more descriptive attribute terms are repeated for easier reference.

5.3.1 Dataset Attribute Tables

There are three attribute tables for the dataset object. The additional tables are needed because the attributes may be multi-valued.

• DLG-E Standards Content Version Number
• Horizontal Coordinate System Granularity
• Vertical Coordinate System Granularity
• Vertical Datum
• Primary Contour Interval
• Secondary Contour Interval
• Supplemental Contour Interval
• State Coverage (multi-valued)
• Nation Coverage (multi-valued)

5.3.2 Theme Attribute Tables

There are four attribute tables for the theme object. The attributes for a theme are partitioned into tables by topic.

• Theme Type
• Theme Activity
• Completion Date

• Primary Source Type
• Source Description
• Source Revision Type
• Source Origin
• Primary Map Edit Year
• Primary Initial Year
• Primary Final Year
• Revision Map Edit Year
• Revision Initial Year
• Revision Final Year

• Lowest Resolution
• Highest Resolution
• Smallest Scale Denominator
• Largest Scale Denominator

• Bathymetric Datum
• Elevation of Bathymetric Datum
• Primary Bathymetric Interval
• Secondary Bathymetric Interval
• Supplemental Bathymetric Interval

5.3.3 Surface Attribute Tables

There is one attribute table for the surface object.

• Completion Date
• Surface Integration Activity

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