14-084r2
License Agreement
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This OGC® Standard specifies standard encoding representations of movement of geographic features. The primary use case is information exchange.
Ogcdoc, moving features, CSV
The following organizations submitted this Document to the Open Geospatial Consortium (OGC):
Central Research Laboratory, Hitachi Ltd.
Center for Spatial Information Science, The University of Tokyo
Defense Systems Company, Hitachi, Ltd.
All questions regarding this submission should be directed to the editor or the submitters:
Name
Representing
OGC member
Akinori Asahara
Central Research Laboratory, Hitachi Ltd.
Yes
Ryosuke Shibasaki
Center for Spatial Information Science, The University of Tokyo
Yes
Nobuhiro Ishimaru
Defense Systems Company, Hitachi Ltd.
Yes
Hiroshi Kanasugi
Center for Spatial Information Science, The University of Tokyo
Yes
David Burggraf
Individual
Yes
Gianluca Luraschi
EMSA (European Maritime Safety Agency)
Yes
Frank Suykens
Luciad
Yes
Chris Little
UK Met Office
Yes
Nadeem Anjum
Google Summer of Code representative through Apache
No
Martin Desruisseaux
GEOMATYS
Yes
Ki-Joune Li
Pusan National University
Yes
The OGC
Abstract Specification does not require changes to accommodate this OGC
standard.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. Open Geospatial Consortium shall not be held responsible for identifying any or all such patent rights. However, to date, no such rights have been claimed or identified.
Recipients of this document are requested to submit, with their comments, notification of any relevant patent claims or other intellectual property rights of which they may be aware that might be infringed by any implementation of the standard set forth in this document, and to provide supporting documentation.
OGC Moving Features consists of the following parts under the general title
Moving Features
Encoding
Part
XML Core
Part
II
Simple CSV
Applications using
moving feature
data, typically representing vehicles or pedestrians, are rapidly increasing. Innovative applications are expected to require the overlay and integration of moving feature data from different sources to create greater social and business value. Examples of applications that require integrated simulation are disaster risk management, traffic information services, security services, navigation for robots, aviation or maritime traffic monitoring, and wildlife tracking and conservation. Moreover, systems relying on single-source moving feature data are now evolving into more integrated systems. Integration of moving feature data from different sources is a key to developing more innovative and advanced applications.
Efforts in this direction therefore should be encouraged by ensuring smoother data exchange because handling and integrating moving feature data will broaden the market for geo-spatial information such as Geospatial Big Data Analysis. ISO 19141:2008 is an existing abstract standard to model moving features; however encoding method is not provided.
Therefore, a comma-separated values (CSV) style encoding for Moving Features is standardized. The defined encoding standard should be ISO 19141:2008 Geographic Information – Schema for moving Features compliant implementation standard applicable for massive data handling.
1. Scope
This OGC
Standard specifies an encoding format to describe the geometries of many features that move as rigid bodies. This OGC
Standard is applicable to features having the following characteristics.
Each moving feature can be described with Schema for Moving Features (ISO19141: 2008).
The number of features simultaneously encoded with this format can be massive (many thousands of features).
All features can be described using common space-time coordinates.
This standard does not address all types of moving features. Examples of features that are out of scope include the following:
Deforming features, such as flood water.
Feature’s geometric representation should not be encoded inline in a geometric complex that contains the geometric representations of other features, since this would require the other features’ representations to be updated as the feature moves.
This standard is focused on the encoding format, thus Web interface and inertial data models are out of scope also.
2. Conformance
Conformance with this specification shall be checked using all the relevant tests specified in Annex A (normative).
3. Normative References
The following normative documents contain provisions which, through reference in this text, constitute provisions of this part of OGC Moving Features. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this part of OGC Moving Features are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies.
[IETF RFC 4180] Y. Shafranovich, “Common Format and MIME Type for Comma-Separated Values (CSV) Files”, IETF RFC 4180, October 2005, available at < http://www.ietf.org/rfc/rfc4180.txt>
[IETF RFC 3629] F. Yergeau, “UTF-8, a transformation format of ISO 10646”, IETF RFC 3629, November 2003, available at
[IETF RFC 2396] IETF RFC 2396, Uniform Resource Identifiers (URI): Generic Syntax. (August 1998)
[ISO 19141:2008] ISO 19141:2008, Geographic information – Schema for moving features
[ISO 19107:2003] ISO 19107:2003, Geographic information – Spatial schema
[ISO 19123:2005] ISO 19123:2005, Geographic information – Schema for coverage geometry and functions
[XMLSchema-2] W3C XMLSchema-2, XML Schema Part 2: Datatypes. W3C Recommendation (28 Oct 2004)
4. Terms and Definitions
For the purposes of this document, the following terms and definitions apply.
4.1
Moving feature
representation, using a local origin and local ordinate
vectors
, of a
geometric object
at a given reference time
[ISO 19141:2008]
4.2
Foliation
one parameter set of geometries
such that each point in the
prism
of the set is in one and only one
trajectory
and in one and only one
leaf
[ISO 19141:2008]
4.3
geometric object
spatial object representing a geometric set
[ISO 19107:2003]
4.4
leaf
geometry at a particular value of the parameter
[ISO 19141:2008]
4.5
trajectory
path of a moving point described by a
one parameter set of points
[ISIO19141:2008]
4.6
one parameter set of geometries
function f from an interval t ∈ [a, b] such that f(t) is a geometry and for each
point
P ∈ f(a) there is a one parameter set of points (called the trajectory of P) P(t) : [a, b] →P(t) such that P(t) ∈ f(t)
[ISO 19141:2008]
4.7
prism
set of
points
in the union of the geometries (or the union of the
trajectories
) of a
one parameter set of geometries
[ISO 19141:2008]
4.8
period
one-dimensional
geometric primitive
representing extent in time
[ISO 19141:2008]
4.9
point
0-dimensional
geometric primitive
, representing a position
[ISO 19107:2003]
4.10
geometric primitive
geometric object
representing a single, connected, homogeneous element of space
[ISO 19107:2003]
4.11
vector
quantity having direction as well as magnitude
[ISO 19123:2005]
5. Conventions
5.1 Abbreviated terms
The following symbols and abbreviated are used in this standard;
ISO
International Organization for Standardization
OGC
Open Geospatial Consortium
1D
One Dimensional
2D
Two Dimensional
3D
Three Dimensional
CSV
Comma Separated Values
6. Overview
6.1 Concepts and standard modularity
Figure 1 illustrates the standard components for encoding and communicating Moving Features data. The four boxes drawn in the figure portray the four modules defined in the OGC® Moving Features standard.
OGC® Moving Features Simple CSV Encoding and OGC® Moving Features Simple Binary Encoding define most fundamental and are data formats to describe moving points and their trajectories. The formats are designed to encode trajectories of moving points compactly as application schemas of IETF RFC 4180 (CSV), NetCDF Discrete Sampling Geometry and so on.
OGC® Moving Features Core, defined in this document, is represented by an XML data encoding for moving points and their trajectories. The format is an extensible format to model and encode movement data for features encoded as pointgeometries.
OGC® Moving Features 1D/2D Geometry and OGC® Moving Features 3D Geometry are defined to encode moving features that have more complex geometries.
Two UML packages are defined in ISO 19141:2008[ISO 19141:2008]: “Geometry Types” and “Prism Geometry”. “Geometry Types” defines the description model of movements including the paths. “Prism Geometry” defines the moving geometry. Two squares drawn with broken lines in Fig. 1 correspond to these packages. The square labelled as “<
Figure
: OGC® Moving Features modularity
6.2 Data model
The data model used by the CSV encoding is equivalent to that used by [Moving Features Core XML]. Figure 2 shows an example for trajectories of three moving points A, B and C. Each trajectory has the start time and the end time. At t=0 (start of all data), all points start moving. Then, at t =1, the movement of A is changed. In the case, the trajectory of A from t=0 to t=1, the trajectory of A from t=1 to t=2, the trajectory of B from t=0 to t=2, and the trajectory of C from t=0 to t=2 are encoded.
Figure
: Example for three trajectories
7. Fundamental rules
7.1 Data structure
OGC Moving Features Simple CSV is based on [IETF RFC4180] (Common Format and MIME Type for Comma-Separated Values (CSV) Files) except the meta-information like definition of each column. Basic encoding-rules are listed in Table 1.
Requirement 7.1 (req/simplecsv/csv_valid):
The encoding restrictions of Moving Features Simple CSV are following.
Any line
shall
be encoded by UTF-8 with LF or CR+LF as the new line character.
The separators
shall
be comma (,).
Columns
shall
start and end with double quotations (”) if the column include double quotations (”).
Any double quotation (”) in a column
shall
be replaced with two double quotations (””) except the first letter and the final letter of the column.
Table 1. Basic encoding-rules (see also [IETF RFC4180])
property
title
property
setting
Character
encoding
UTF-8 [IETF
RFC 3629]
New
line character
either
LF or CR+LF
Separators
comma
(, ) [0x2C]
Columns
Each
column starts with a double quotation (“) [] and ends with a double
quotation. The double quotations can be omitted if the content does not
include any double quotation.
Escape
sequence
double quotation included by the column content must be replaced to two
double quotations (“”).
The meta-information is described by “header lines,” which start with “@”[0x40], shown at the top of the moving features data. “Trajectory lines,” which describe trajectories of the moving features, follow the header lines. The structure is illustrated in Figure 3. Several header lines are shown at first. Following the header lines, trajectory lines are written.
Requirement 7.2 (req/simplecsv/overall_structure):
Header lines
shall
be shown before Trajectory lines.
Figure
: CSV structure
7.2 Omissible columns
Some types of columns defined by the Moving Features Simple CSV Encoding are omissible. The omitted column is written as an empty column, for example,
@stboundedby,urn:x-ogc:def:crs:EPSG:6.6:4326,2D,50.23 9.23,50.31 9.27,2012-01-17T12:33:41Z,2012-01-17T12:37:00Z,,
The last column of the above line is omitted. The omitted column is interpreted as the default value.
8. Header lines
8.1 structure
@[metadata name],[value 1], [value 2]...
8.1.1 Description
A header line contains a metadata-name-column and several value-columns. The metadata-name-column, which starts with “@”, specifies type of the meta-information which this line defines. The value-columns set values of the meta-information. For example, if “@stboundedby” is shown, the line defines the spatio-temporal bounding-box of the moving features. The value-columns following “@stboundedby” explicit the geometry of the spatial bounding-box and the time period of the moving features.
Requirement 8.1 (req/simplecsv/headerline):
Any header lines
shall
start with “@”.
8.2 Contents
8.2.1 @stboundedby
@stboundedby,[srid],[dim],[upper_left],[lower_right],[start
time],[end time],[time encode]
The @stboundedby line determines the spatio-temporal boundary of moving features. This line is equivalent to mf:STBoundedBy defined by [OGC Moving Features Core].
Requirement 8.2 (req/simplecsv/stboundedby):
One “@stboundedby” line consistent with the trajectory lines
shall
be included by the header lines.
srid
The spatial reference system used in the moving feature is specified.
dim (omissible)
This column specifies the dimension of geometries.
- “2D”(default): 2D data are included
- “3D”: 3D data are included
upper left
The upper-left corner of the spatial boundary is stated here. x-coordinate and y-coordinate are sequentially written with a separator “ “(white-space).
lower right
The lower-right corner of the spatial boundary is stated here. x-coordinate and y-coordinate are sequentially written with a separator “ “(white-space).
start time
The time before starting of all movements is written in xsd:dateTime style.
end time
The time after ending of all movements is written in xsd:dateTime style
time encode (omissible)
The column shows the unit of time used in the Trajectory lines. “start time” and “end time” are described the offset from the “start time” specified by the @stboundedby line.
- “sec”(default): the offset described in seconds is encoded in xsd:decimal style.
- “minute”: the offset described in minutes is encoded in xsd:decimal style.
- “absolute”: an absolute date time is encoded by xsd:dateTime style.
8.2.2 @columns
@columns,”mfidref”,”trajectory”,[VaryingAttrDef(1)
Name], [VaryingAttrDef(1) Type],…, [VaryingAttrDef(n) Name],
[VaryingAttrDef(n) Type]
Requirement 8.3 (req/simplecsv/column):
Only one “@columns” line
shall
be included by the header lines.
“mfidref”
“mfidref”, which is the first row of each datum, is used in order to identify the moving feature. Thus the first column of the header is always fixed as “mfidref”.
“trajectory”
The second column defines the spatio-temporal geometry of moving features.
VaryingAttrDef(n) Name/Type
The column which defines an attribute used in the foliation is equivalent to mf:VaryingAttrDef [Moving Features Core]. If the moving features do not have any variable attributes, these columns can be omitted.
A pair of the “VaryingAttrDef(n) Name” column and “VaryingAttrDef(n) Type” column defines one varying attribute. “VaryingAttrDef(n) Name” defines the name of the attribute with a xsd:token style text. The “VaryingAttrDef(n) Type” column following the “VaryingAttrDef(n) Name”, which the XSD data type (defined in [XMLSchema-2] as built-in data types)is used to specify, defines the type of the attribute value. The supported data types used in Moving Features Encoding Simple CSV are listed in the following table.
Table 2. Supported data types
XSD
data type
xsd:boolean
xsd:decimal
xsd:integer
xsd:string
xsd:dateTime
xsd:anyURI
Multiple VaryingAttrDef column-pairs can be included by the @columns line in order to define multiple attributes.
8.2.3 @foliation (omissible)
@foliation,[order]
A @foliation line defines properties of the foliation described in the CSV data. The @foliation line is omissible if all values are set default values.
order
Order column defines appearing order of trajectories. The possible values are enumerated in the following code table.
Table 3. code-table for “order” attribute
Attribute values
Definitions
Default
Time
mf:Trajectory elements ordered by time strictly
Yes
Sequential
mf:Trajectory elements which are parts of one track are ordered by time
9. Trajectory lines (Data body)
9.1 Structure
[mfidref],[start
time], [end time],[points of linestring],[attr]
Description
Trajectory lines contain the spatio-temporal geometries for moving features. The data model of the trajectory lines is equivalent to that of mf:LinearTrajectory defined in [Moving Features Core XML]. mf:LinearTrajectory element is the spatio-temporal line-string, which is similar to gml:LineString. The mf:LinearTrack is a special trajectory that consists of a single segment with linear interpolation.
Requirement 9.1 (req/simplecsv/trajectoryline):
The trajectory lines
shall
statisfy the following restrictions.
The number of columns and the datatype of the columns are consistent with the definition in the header line part.
The order of the trajectory lines is consistent with the restriction stated by the @foliation line in the header line part.
Any pair of trajectory lines having common ‘mfid’ satisfies the following condition: start time of one trajectory line is later than or equal to end time of another trajectory line otherwise end time of one trajectory line is earlier than or equal to start time of another trajectory line.
9.2 Contents
Trajectory
mfidref
The texts specifying the moving feature (i.e. person ID, vehicle ID, etc.)
start time
The column specifies the start time of the movement. The encoding style is determined in the @stboundedby line.
end time
The column specifies the end time of the movement. The encoding style is determined in the @stboundedby line.
points of linestring
The positions of the trajectory are specified. The x-coordinate value (or longitude), the y-coordinate value (or latitude) and the z-coordinate value (or elevation) are separated by whitespace characters. A separator between points is similarly a whitespace. If SRS specifies the 2D space, the following encoding style is applied.
[x-coordinate (1)] [y-coordinate (1)] [x-coordinate (2)] [y-coordinate (2)] …
Otherwise, if SRS specifies 3D space, the following encoding style is applied.
[x-coordinate (1)] [y-coordinate (1)] [z-coordinate (1)] [x-coordinate (2)] [y-coordinate (2)] [z-coordinate (2)]…
attr
Attr consists of multiple columns which describe the attribute values. An example is following.
12.0,313.1,,4,5,a<b,123
Some characters may need to be escaped here. < (less than), > (greater than), “ (double quotation), ‘ (single quotation), and & (ampersand) must be replaced with the entity references defined in XML. Space, tab, and comma are written in escape sequences \s, \t, and \b, respectively. If the value equals the previous value, the text for the value can be omitted.
10. Example codes
10.1 Example 1: people movements
@stboundedby,urn:x-ogc:def:crs:EPSG:6.6:4326,2D,50.23 9.23,50.31 9.27,2012-01-17T12:33:41Z,2012-01-17T12:37:00Z,sec
@columns,mfidref,trajectory,state,xsd:token,”type code”,xsd:integer
a,10,150,11.0 2.0 12.0 3.0,walking,1
b,10,190,10.0 2.0 11.0 3.0,walking,2
a,150,190,12.0 3.0 10.0 3.0,walking,2
c,10,190,12.0 1.0 10.0 2.0 11.0 3.0,vechicle,1
Annex A
(Normative)
Abstract Test Suite
This Annex specifies an Abstract Test Suite which shall be passed in completeness by any implementation claiming conformance with this Moving Features XML Core. Test identifiers below are relative to
A.1 Conformance Class:
The OGC URI Identifier of this conformance classes is
A.1.1 CSV Validity
Test id
conf/simplecsv/csv-valid
Requirements
7.1 req/simplecsv/csv_valid
Test Purpose
Verify that any line of the document is well-formed as CSV .
Test Method
Validate the document conformant with IETF RFC4180.
A.1.2 Overall structure
Test id
conf/simplecsv/overall_structure
Requirements
7.1 req/simplecsv/overall_structure
8.1 req/simplecsv/headerline
Test Purpose
Verify that the document consists of header lines and trajectory lines .
Test Method
Validate the document has two part. The first part consists of header lines which start with “@” and the second part consists of trajectory lines which do not start with “@”.
A.1.3 Spatio-temporal boundary
Test id
conf/simplecsv/stboundedby
Requirements
8.2 req/simplecsv/stboundedby
Test Purpose
Verify the spatio-temporal boundary is defined.
Test Method
Validate that a line starting with @stboundedby is included in the headerlines.
A.1.4 Column definition
Test id
conf/simplecsv/column
Requirements
8.3 req/simplecsv/column
Test Purpose
Verify the spatio-temporal boundary is defined.
Test Method
Validate that a line starting with @columns is included in the headerlines.
A.1.5 Trajectory definition
Test id
conf/simplecsv/trajectory
Requirements
9.1 req/simplecsv/trajectory
Test Purpose
Verify that all trajectory lines are valid and consistent with attribute definition at the header line part. In addition, verify the uniqueness of “mfid” at a temporal snapshot.
Test Method
Validate that the following conditions are satisfied.
The order of trajectory lines is consistent with the @foliation line.
The trajectory lines are consistent with attribute definition at the “@columns” line of header line part, namely, the consistency of the number of columns and the data type.
Any pair of trajectory lines having common ‘mfid’ satisfies following condition: start time of one trajectory line is later than or equal to end time of another trajectory line, otherwise end time of one trajectory line is earlier than or equal to start time of another trajectory line.
Revision History
Date
Release
Author
Paragraph modified
Description
2014/11/13
OGC 14-084r2
Akinori
Asahara
W3C
XMLSchema-2 was added
2014/11/13
OGC 14-084r2
Akinori
Asahara
8.2.3.2
reference to xsd data types were added
US