ASTM D5714-95
(Specification)Standard Specification for Content of Digital Geospatial Metadata
Standard Specification for Content of Digital Geospatial Metadata
SCOPE
1.1 This specification covers the information content of metadata for a set of digital geospatial data. This specification provides a common set of terminology and definitions for concepts related to these metadata.
1.2 The use of the term "geographic information system" and its definition in this specification is not intended to introduce a standard definition.
1.3 This specification covers minimum content and processing requirements for geospatial metadata.
1.4 There are at least three categories of use for geospatial metadata: (1) to accompany data transfers as documentation, (2) internal, on-line documentation of processing steps and data lineage, and (3) as stand-alone data set synopses for use by spatial data catalogs, indexes, and referral services.
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Standards Content (Sample)
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Designation: D 5714 – 95
AMERICAN SOCIETY FOR TESTING AND MATERIALS
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Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Specification for
Content of Digital Geospatial Metadata
This standard is issued under the fixed designation D 5714; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope coordinate system obtained by measuring parallel to the x-axis
(“the 8x’ value”).
1.1 This specification covers the information content of
3.2 accuracy—the degree of conformity of a measured or
metadata for a set of digital geospatial data. This specification
calculated value to some recognized standard or specified
provides a common set of terminology and definitions for
value. This concept involves the systematic and random error
concepts related to these metadata.
of an operation.
1.2 The use of the term “geographic information system”
3.3 altitude—elevation above or below a reference datum,
and its definition in this specification is not intended to
as defined in Federal Information Processing Standard 70-1.
introduce a standard definition.
See also elevation.
1.3 This specification covers minimum content and process-
3.4 area—a generic term for a bounded, continuous, two-
ing requirements for geospatial metadata.
dimensional object that may or may not include its boundary.
1.4 There are at least three categories of use for geospatial
3.5 area chain—a chain that explicitly references left and
metadata: (1) to accompany data transfers as documentation,
right polygons and not start and end nodes. It is a component
(2) internal, on-line documentation of processing steps and
of a two-dimensional manifold.
data lineage, and (3) as stand-alone data set synopses for use by
3.6 area point—a representative point within an area usu-
spatial data catalogs, indexes, and referral services.
ally carrying attribute information about that area.
2. Referenced Documents
3.7 attribute—a defined characteristic of an entity type (for
example, composition).
2.1 ANSI Standards:
3.8 attribute value—a specific quality or quantity assigned
ANSI X3.51 Representations of Universal Time, Local
to an attribute (for example, steel), for a specific entity
Time Differentials, and United States Time Zone Refer-
instance.
ence for Information Interchange
3.9 chain—a directed non-branching sequence of non-
ANSI X3.30 Representation for Calendar Date and Ordinal
intersecting line segments or arcs bounded by nodes, or both,
Date for Information Interchange
not necessarily distinct, at each end. Area chain, complete
ANSI Z39.50 Information Retrieval Service Protocol for
chain, and network chain are special cases of chain, and share
Open Systems Interconnection
all characteristics of the general case as defined above.
2.2 SDTS Standard:
3.10 complete chain—a chain that explicitly references left
Federal Information Processing Standard 173 in SDTS
and right polygons and start and end nodes. It is a component
70-1
of a two-dimensional manifold.
2.3 Military Standards:
3.11 compound element—a group of data elements and
MIL-STD-600006 Vector Product Format
other compound elements. Compound elements represent
MIL-A-89007 Military Specification ARC Digitized Raster
higher-level concepts that cannot be represented by individual
Graphics (ADRG)
data elements.
3. Terminology
3.12 coordinates—pairs of numbers expressing horizontal
distances along orthogonal axes; alternatively, triplets of num-
3.1 abscissa—the coordinate of a point in a plane cartesian
bers measuring horizontal and vertical distances.
3.13 data element—a logically primitive item of data.
This specification is under the jurisdiction of ASTM Committee D-18 on Soil
3.14 data set—a file or files that contain related geometric
and Rock and is the direct responsibility of Subcommittee D18.01 on Surface and
Subsurface Characterization. and attribute information; a collection of related data.
Current edition approved April 15, 1995. Published January 1996.
3.15 depth—perpendicular distance of an interior point
Available from American National Standards Institute, 11 W. 42nd St., 13th
from the surface of an object.
Floor, New York, NY 10036.
3.16 developable surface—a surface that can be flattened to
Available from Spatial Data Transfer Standard, Washington Department of
Commerce NIST, 11 W. 42nd St., 13th Floor, New York, NY 10036. (Supportive
form a plane without compressing or stretching any part of it.
Terminology)
Examples include cones and cylinders.
Available from Standardization Documents Order Desk, Bldg. 4 Section D, 700
3.17 digital image—a two-dimensional array of regularly
Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.
D 5714
spaced picture elements (pixels) constituting a picture. 3.31 grid cell—a two-dimensional object that represents the
smallest non-divisible element of a grid.
3.18 digital volume—a three-dimensional array of regularly
spaced volume elements (voxels) constituting a volume. 3.32 GT-polygon—an area that is an atomic two-
dimensional component of one and only one two-dimensional
3.19 domain—in the definition of the elements in this
manifold. The boundary of a GT-polygon may be defined by
specification, the domain identifies valid values for a data
GT-rings created from its bounding chains. A GT-polygon may
element.
also be associated with its chains (either the bounding set, or
3.20 elevation—conforming to Federal Information Pro-
the complete set) by direct reference to these chains. The
cessing Standard 70-1, the term “altitude” is used in this
complete set of chains associated with a GT-polygon may also
specification, rather than the common term elevation.
be found by examining the polygon references on the chains.
3.21 entity instance—a spatial phenomenon of a defined
3.33 GT-ring—a ring created from complete or area chains,
type that is embedded in one or more phenomena of different
or both.
type, or that has at least one key attribute value different from
3.34 horizontal—tangent to the geoid or parallel to a plane
the corresponding attribute values of surrounding phenomena
that is tangent to the geoid.
(for example, the 10th Street Bridge).
3.35 implicit position—method of identifying positions by a
3.22 entity point—a point used for identifying the location
place in an array of values.
of point features (or areal features collapsed to a point), such as
3.36 interior area—an area not including its boundary.
towers, buoys, buildings, places, etc.
3.37 label point—a reference point used for displaying map
3.23 entity type—the definition and description of a set into
and chart text (for example, feature names) to assist in feature
which similar entity instances are classified (for example,
identification.
bridge).
3.38 layer—an integrated, areally distributed, set of spatial
3.24 explicit position—method of identifying positions di-
data usually representing entity instances within one theme, or
rectly by pairs (for horizontal positions) or triplets (for hori-
having one common attribute or attribute value in an associa-
zontal and vertical positions) of numbers.
tion of spatial objects. In the context of raster data, a layer is
3.25 G-polygon—an area consisting of an interior area, one
specifically a two-dimensional array of scaler values associated
outer G-ring and zero or more nonintersecting, non-nested
with all or part of a grid or image.
inner G-rings. No ring, inner or outer, shall be collinear with or
3.39 line segment—a direct line between two points.
intersect any other ring of the same G-polygon.
3.40 link—a topological connection between two nodes. A
3.26 G-ring—a ring created from strings or arcs, or both.
link may be directed by ordering its nodes.
3.27 geoid—a mathematical representation of the surface of
3.41 media—the physical devices used to record, store, or
the earth accounting for local geodetic and gravity measure-
transmit data, or combination thereof.
ments.
3.42 metadata—data about the content, quality, condition,
3.28 geospatial data—information that identifies the geo-
and other characteristics of data.
graphic location and characteristics of natural or constructed
3.43 network—a graph without two-dimensional objects. If
features and boundaries on the earth. This information may be
projected onto a two-dimensional surface, a network can have
derived from, among other things, remote sensing, mapping,
either more than one node at a point or intersecting links or
and surveying technologies.
chains, or both, without corresponding nodes.
3.29 graph—a set of topologically interrelated zero-
3.44 network chain—a chain that explicitly references start
dimensional (node), one-dimensional (link or chain), and
and end nodes and not left and right polygons. It is a
sometimes two-dimensional (GT-polygon) objects that con-
component of a network.
form to a set of defined constraint rules. Numerous rule sets
3.45 node—a zero-dimensional object that is a topological
can be used to distinguish different types of graphs. Three such
junction of two or more links or chains, or an end point of a
types, planar graph, network, and two-dimensional manifold,
link or chain.
are used in this specification. All three share the following
3.46 object—a digital representation of all or part of an
rules: each link or chain is bounded by an ordered pair of
entity instance.
nodes, not necessarily distinct; a node may bound one or more
3.47 ordinate—the coordinate of a point in a plane cartesian
links or chains; and links or chains may only intersect at nodes.
coordinate system obtained by measuring parallel to the y-axis
Planar graphs and networks are two specialized types of
(“the 8y’ value”).
graphs, and a two-dimensional manifold is an even more
specific type of planar graph. 3.48 phenomenon—a fact, occurrence, or circumstance.
Route 10, George Washington National Forest, and Chester-
3.30 grid—(1) a set of grid cells forming a regular, or nearly
field County are all phenomena.
regular, tessellation of a surface; (2) a set of points arrayed in
a pattern that forms a regular, or nearly regular, tesselation of 3.49 pixel—two-dimensional picture element that is the
smallest non-divisible element of a digital image.
a surface. The tessellation is regular if formed by repeating the
pattern of a regular polygon, such as a square, equilateral 3.50 planar graph—the node and link or chain objects of
triangle, or regular hexagon. The tessellation is nearly regular the graph occur or can be represented as though they occur
if formed by repeating the pattern of an“ almost” regular upon a planar surface. Not more than one node may exist at any
polygon such as a rectangle, non-square parallelogram, or given point on the surface. Links or chains may only intersect
non-equilateral triangle. at nodes.
D 5714
3.51 point—a zero-dimensional object that specifies geo- characters, “date” for day of the year, and “time” for time of the
metric location. One coordinate pair or triplet specifies the day.
location. Area point, entity point, and label point are special
3.66 universe polygon—defines the part of the universe that
implementations of the general case. is outside the perimeter of the area covered by other GT-
polygons (“covered area”) and completes the two-dimensional
3.52 primitive—the quality of not being subdivided; atomic.
manifold. This polygon completes the adjacency relationships
3.53 processing step—a discrete unit of processing that
of the perimeter links. The boundary of the universe polygon is
affects either the data or metadata in a data set.
represented by one or more inner rings and no outer ring.
3.53.1 Discussion—Different GISs may discretize processes
Attribution of the universe polygon may not exist, or may be
differently, and so the definition of processing step depends
substantially different from the attribution of the covered area.
somewhat on the particular GIS. Processing steps shall include
3.67 vector—composed of directed lines.
all steps followed to automate the data set, such as digitizing or
3.68 vertical—at right angles to the horizontal; includes
scanning. Processing steps shall also include data-set reviews.
altitude and depth.
A data set review typically will not alter the basic data, but the
3.69 VPF—the vector product format (see 2.3).
review with its results should be documented in the metadata.
3.70 void polygon—defines a part of the two-dimensional
3.54 quality—an essential or distinguishing characteristic
manifold that is bounded by other GT-polygons, but otherwise
necessary for cartographic data to be fit for use.
has the same characteristics as the universe polygon. The
3.55 raster—one or more overlapping layers for the same
geometry and topology of a void polygon are those of a
grid or digital image.
GT-polygon. Attribution of a void polygon may not exist, or
3.56 raster object—one or more images or grids, or both,
may be substantially different from the attribution of the
each grid or image representing a layer, such that correspond-
covered area.
ing grid cells or pixels, or both, between layers are congruent
3.71 voxel—a three-dimensional element that is the smallest
and registered.
non-divisible element of a digital volume.
3.57 resolution—the minimum difference between two in-
3.72 Definitions—These definitions are provided to clarify
dependently measured or computed values which can be
terms used in this specification. Definitions are from SDTS,
distinguished by the measurement or analytical method being
FIPS 173.
considered or used.
3.58 ring—sequence of nonintersecting chains or strings or
4. Data Element Description
arcs, or both, with closure. A ring represents a closed boundary
4.1 A data element is a logically primitive item of data. The
but not the interior area inside the closed boundary.
entry for a data element includes the name of the data element,
3.59 schema—the definition of table columns, relations,
the definition of the data element, a description of the values
data, Domain, and other elements of a data base, often
that can be assigned to the data element. The form for the
illustrated using an entity-relationship diagram.
definition of the data elements is:
3.60 SDTS—the Spatial Data Transfer Standard (see 2.2).
Data element name—definition.
3.61 spatial data—see geospatial data. Type:
Domain:
3.62 stratum—one of a series of layers, levels, or gradations
Tag Name:
in an ordered system. For this specification, the term is used in Tag Value:
the sense
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