¶ Description hierarchy (IFC version)
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<LandXML> | Transfer file | ||||||
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<Units><Metric> | Units (Metric) | ||||||
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<CoordinateSystem> | Coordinate and elevation system | ||||||
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<Start> | Base point | ||||||
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<Feature> | "IM_coordTransformation" extension coordinate tranformation |
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<Feature> | "IM_controlPoint" extension transformation control point |
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<Project> | Project | ||||||
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<Feature> | "IM_codings" extension type coding systems |
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<Application> | Application | ||||||
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<Author> | Authors | ||||||
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<FeatureDictionary> | Referenced feature dictionary | ||||||
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<DocFileRef> | External reference documentation | ||||||
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<im:LocalCoordinateTransformation> | Coordinate Transformation Definition | ||||||
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<im:SourceCRS> | Source geographic coordinate system | ||||||
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<im:Ellipsoid> | |||||||
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<im:PrimeMeridian> | |||||||
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<im:TargetCRS> | Target geographic coordinate system | ||||||
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<im:Ellipsoid> | |||||||
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<im:PrimeMeridian> | |||||||
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<im:DatumTransformation> | Datum transformation from Source to Target datum | ||||||
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<im:Helmert3D> | |||||||
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<im:Projection> | Projection used for projecting the geographical coordinates to a plane | ||||||
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<im:TransverseMercator> | |||||||
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<im:LocalTransformation> | Transformation from the projected coordinates to the final local coordinates | ||||||
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<im:Helmert2D> | |||||||
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<im:FittedPlane> | |||||||
¶ 1.1 Contents
The following items are defined in the header:
The root element of the file
units of measurement
coordinate and height systems and base point
project
the type coding systems for the design content
the application and author of the file
definitions of the extensions
The goal is that all plan information can be presented in the same file. If the content is composed of parts that employ different coordinate or unit systems, each of these parts is separated into its own file.
NB: even if the language of the file is set to "Finnish", scandic and special characters should not used in Inframodel content in names, e.g. "väylä 2" should be spelled "vayla 2".
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Header contents | example |
¶ 1.2 Transfer file
The root element <LandXML> of the transfer file is used by software to check the validity of the file structure. It shall have the following attributes set:
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date | date |
[yyyy-mm-dd] |
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time | time | [hh:mm:ss] |
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version | the schema version used in the file |
[1.2] |
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language | the language of the content |
[Finnish] |
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readOnly | write protection |
off / on [false | true] |
The namespaces in Inframodel file shall be the following:
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The default namespace to be used without prefix for all LandXML elements specialized for Inframodel in schema inframodel.xsd shall is set in the root element as xmlns="http://buildingsmart.fi/inframodel/404" |
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The namespace for elements in Inframodel extension schema im.xsd (if used in the file) to be used with prefix "im" shall is set in the root element as xmlns:im="http://buildingsmart.fi/im/404" |
| The types in Inframodel enumerations schema inframodelEnumerations.xsd are included in the http://buildingsmart.fi/inframodel/404 namespace |
Note: The namespace URI is not meant to be used to look up information. Its sole purpose is to give the namespace a unique name.
The schema locations may be set in an Inframodel transfer file, in which case XML Schema Instance namespace shall be set in the root element: xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance
The following schema locations can be set to access online:
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The schema location for the default namespace can be set in the root element as xsi:schemaLocation="http://buildingsmart.fi/inframodel/404 /schema/4.0.4/inframodel.xsd" |
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Additionally, if elements from im namespace are used in the file, the schema location can be set in the root element as xsi:schemaLocation="http://buildingsmart.fi/inframodel/404 /schema/4.0.4/inframodel.xsd http://buildingsmart.fi/im/404 /schema/4.0.4/im.xsd" |
| The Inframodel enumerations schema inframodelEnumerations.xsd location is set automatically by being included in the default schema |
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<LandXML> | schema documentation | |
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<LandXML> | root element short example |
¶ 1.3 Units
The units used in the file are defined by the <Units> element. When using a metric unit system the units are defined under the sub-element <Units>.<Metric>. The following table lists recommended units for inframodel file transfers. It is possible to diverge from these recommendations if another unit is more appropriate for the content. The inframodel recommended units are bolded, and in some cases are not the same as the LandXML default units (underlined). If some part of the plan employs different units from the rest of the project, it is recommended that either the divergent units be converted to common units or that the divergent part is presented as a separate file with its own units. Please see the example of descriping water supply and sewerage units in millimeters.
Inframodel file transfers use grads as default direction (directionUnit) and angular (angularUnit) units. These are defined counter-clockwise from the base direction. In angular definitions the base direction is east, and in direction definitions it is north. Defining the flowUnit is optional.
Numeric precision in Inframodel exchange: all measures shall be given with six decimals (regardless of the number of digits before decimal point.).
Metric units <Units>.<Metric>:
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areaUnit | area units |
[hectare | squareMeter | squareMillimeter | squareCentimeter] |
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linearUnit | distance |
[millimeter | centimeter | meter | kilometer] |
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volumeUnit | volume |
[cubicMeter | liter | hectareMeter] |
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temperatureUnit | temperature |
[celsius | kelvin] |
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pressureUnit | pressure |
[HPA | milliBars | mmHG | millimeterHG] |
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diameterUnit | diameter |
[millimeter | centimeter | meter | kilometer] |
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widthUnit | width |
[millimeter | centimeter | meter | kilometer] |
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heightUnit | height |
[millimeter | centimeter | meter | kilometer] |
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velocityUnit | velocity |
[metersPerSecond | kilometersPerHour] |
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flowUnit | flow |
[cubicMeterSecond | literPerSecond | literPerMinute] |
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angularUnit | angle |
[radians | grads | decimal degrees | decimal dd.mm.ss] |
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directionUnit | direction |
[radians | grads | decimal degrees | decimal dd.mm.ss] |
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latLongAngularUnit | angles of latitude and longitude |
[radians | grads | decimal degrees | decimal dd.mm.ss] |
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elevationUnit | elevation unit |
[meter | kilometer | feet | miles] |
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<Units> | schema documentation | |
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<Units> | short example |
¶ 1.4 Coordinate and height systems
The height and coordinate system information is defined in the element <CoordinateSystem>. At least one coordinate system must be defined:
Exactly one horizontal system shall defined using the European Petrol Survey Group (EPSG) naming system, or some other local system in current use; the Open Geospatial Consortium (OGC) naming system shall not be used in Inframodel from version 4.0 onward. The EPSG coordinate system is set in the attribute epsgCode as a valid code without prefix. If a local horizontal coordinate system is used instead of a EPSG system, it is set using the attribute horizontalCoordinateSystemName (and the desc attribute can provide informal information about the system used).
Optionally, one vertical coordinate system can be specified in the attribute verticalCoordinateSystemName; this can be either using a EPSG namimg system (EPSG prefix and code, to be given here also when it is the same as for horizontal system), or a local vertical coordinate system (and the desc attribute can be used to provide informal information about the system used).
It is also possible to set a rotationAngle for the coordinate system.
The name attribute should not be used in Inframodel version 4.0.4.
Attributes of <CoordinateSystem>:
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desc | optional informal information about vertical or horizintal system when identified by other than EPSG system code | e.g. [Vertical coordinate system: Maanmittauslaitos N 60] NB: Should not be used for EPSG coordinate system |
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name | name of the coordinate system |
NB: Should not be used in Inframodel |
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epsgCode | EPSG code identifying horizontal system (or both horizontal and vertical, in which case the same code shall be given also in verticalCoordinateSystemName) | e.g. [3067] |
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horizontalCoordinateSystemName | name of the horizintal coordinate system when not using EPSG system |
e.g. [KKJ / Finland zone 4] ATTN! Shall not be set when using EPSG system |
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rotationAngle | rotation angle of the coordinate system |
in angular units, e.g. [0] |
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verticalCoordinateSystemName | name of the vertical coordinate system, even when the same system is used for horizontal |
e.g. [EPSG:3900] when using code from EPSG system e.g. [MML:N60] when using other than code from EPSG system |
The optional base point of the coordinate system is given using the element <CoordinateSystem>.<Start>. The point is given as a 3D coordinate point, with three space delimited values.
<Start>northing easting elevation</Start>
For transformation between source geographic coordinate system sourceCRS and target local system targetCRS, a set of control points may be given under "IM_coordTransformation" <Feature> extension as "IM_controlPoint" extensions, where each point has latitude, longitude and altitude values in source system, and corresponding local system northing, easting and elevation values.
More detailed coordinate transformation parameters may be transferred using the <LocalCoordinateTransformation> element as explaned below in 1.4.1.
"IM_coordTransformation" <Feature>
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name | optional name | ||||
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code | code | ["IM_coordTransformation"] | |||
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source | source | [inframodel] | |||
| Parameters <Property> | ||||||
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label | [sourceCRSname] | name of the source geographic coordinate system |
value | e.g. [WSG84] | |
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label | [sourceEPSGcode] | EPSG code of the source geographic coordinate system |
value | e.g. [4326] | |
| "IM_controlPoint" <Feature> - Control point 1 |
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name | optional name | ||||
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code | code | [IM_controlPoint] | |||
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source | source | [inframodel] | |||
| Parameters <Property> | ||||||
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label | [useHorizontal] | shall be set to [yes] if the point should be used for calculating the horizontal transformation |
value | [yes | no] | |
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label | [useVertical] | shall be set to [yes] if the point should be used for calculating the vertical transformation |
value | [yes | no] | |
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label | [latitude] | latitude value in source CRS in latLongAngularUnit |
value | ||
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label | [longitude] | longitude value in source CRS in latLongAngularUnit |
value | ||
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label | [altitude] | altitude value in source CRS in elevationUnit |
value | ||
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label | [northing] | northing coordinate value in target system in linearUnit |
value | ||
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label | [easting] | easting coordinate value in target system in linearUnit |
value | ||
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label | [elevation] | elevation value in source CRS in elevationUnit |
value | ||
¶
1.4.1 Local Coordinate Transformation parameters
The exact parameters of a particular Local Coordinate Transformation are given using <im:LocalCoordinateTransformation> element in im-extension schema as <any> element under <LandXML>. The xml schema (im.xsd) for the extension schema elements is available at Inframodel schema page.
Coordinate systems use a reference ellipsoid, defined by the semi-major and semi-minor axis, to approximate the shape of the Earth. The datum is then defined by the ellipsoid and its location and orientation, i.e. different datums can use the same ellipsoid but its position varies.
For example, the WGS84 system uses a reference ellipsoid with a semi-major axis of 6 378 137m and a semi-minor axis of 6 356 752m. The ellipsoid center is located at the Earth's center of mass.
1) SourceCRS
Attributes of <im:SourceCRS>:
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name | name of the source CRS | e.g. [WSG84] |
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epsg | epsg code of the source CRS | e.g. [4326] |
The <SourceCRS> has two child-elements: <im:Ellipsoid> and <im:PrimeMeridian>
<im:Ellipsoid> attributes
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name | name | |
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semiMajorAxis | the equatorial radius of the reference ellipsoid (meters) |
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inverseFlattening | inverse flattening f is a unitless measure of how much the semi-minor axis b is compressed relative to the semi-major axis a, i.e. f = (a-b)/a |
<im:PrimeMeridian> attributes
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name | name | |
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value | offset to the Greenwich Prime meridian, positive to the east (decimal degrees) |
2) TargetCRS
The element <im:TargetCRS> has no attributes, but two child-elements: <im:Ellipsoid> and <im:PrimeMeridian>
<im:Ellipsoid> attributes
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name | name | |
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semiMajorAxis | the equatorial radius of the reference ellipsoid (meters) |
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inverseFlattening | inverse flattening f is a unitless measure of how much the semi-minor axis b is compressed relative to the semi-major axis a, i.e. f = (a-b)/a |
<im:PrimeMeridian> attributes
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name | name | |
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value | offset to the Greenwich Prime meridian, positive to the east (decimal degrees) |
3) DatumTransformation
Helmert3D <im:DatumTransformation>.<im:Helmert3D> performs a coordinate transformation from one datum to another.
<im:Helmert3D> attributes
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rotationX | counter-clockwise rotation with respect to x axis (seconds of arc) | |
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rotationY | counter-clockwise rotation with respect to y axis (seconds of arc) |
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rotationZ | counter-clockwise rotation with respect to z axis (seconds of arc) |
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translationX | shift in the direction of x axis (meters) |
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translationY | shift in the direction of y axis (meters) |
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translationZ | shift in the direction of z axis (meters) |
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scale | uniform scaling factor for all axes (ppm) |
4) Projection
Transverse Mercator Map projection <im:Projection>.<im:TransverseMercator> transforms geographical coordinates (latitude, longitude, altitude) to a plane (x, ,y, z). The grid origin is taken on the central latitude and longitude, and false easting and northing is then applied to prevent negative coordinates west or south of the origin.
<im:TransverseMercator> attributes
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falseEasting | the distance of the true grid origin east of the false origin (meters) |
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falseNorthing | the distance of the true grid origin north of the false origin (meters) |
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longitude0 | central longitude, i.e. offset from Greenwich prime meridian, positive to the east (decimal degrees) |
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latitude0 | central latitude, i.e. offset from the Equator, positive to the north (decimal degrees) |
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scale0 | unitless scaling factor for the projection, used as is |
5) Local Transformation
In LocalTransformation <im:LocalTransformation>, Helmert2D <im:Helmert2D> transforms the projected (x,y,z) coordinates to the local coordinate system. FittedPlane <im:FittedPlane> corrects height values using a plane as the geoid model. The corrected height at point (x,y,z) is z_corrected = z + (a*x + b*y +c).
<im:Helmert2D> attributes
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rotation | counter-clockwise rotation around the axis (seconds of arc) |
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scale | uniform scaling factor for all axes, used as is. |
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dn | shift along the north axis (meters) |
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de | shift along the east axis (meters) |
<im:FittedPlane> attributes
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a | unitless coefficient for x coordinate |
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b | unitless coefficient for y coordinate |
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c | constant (meters) |
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<CoordinateSystem> | schema documentation | |
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<CoordinateSystem> | short example |
¶ 1.5 Project
It is mandatory to define a name and a description desc for the <Project>. The description can e.g. contain the project long name or code. The optional state attribute can be used to describe the state of the project and its content.
Attributes of <Project>:
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name | name | e.g. [inframodel example] |
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desc | description |
project description, long name or code, e.g. [12345] |
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state | state |
[abandoned] [demolished] [existing] [proposed] |
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<Project> | schema documentation | |
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<Project> | short example |
¶ 1.6 Type coding systems
The meaning (semantic) of the points, lines and surfaces is defined in the file. The parties of the project agree on a type coding systems that are used in the data transfer and they are set in the "IM_codings" extension using <Feature> element under <Project> defining:
1) The terrain description coding system (source data points and breaklines)(terrainCoding)
2) The surface description coding system (surfaceCoding)
3) The coding system for planned infrastructure objects (including alignments and breaklines, pipe netweorks, plan features) (infraCoding)
4) Additional or alternative type coding systems used in the project (proprietaryInfraCoding)
The existing terrain description contains source data points and breaklines. The surface description consists of the individual surfaces of the base data (terrain and ground layers) or the planned route or areal structures as TIN surface model or string line model. In addtion to surfaces, planned objects may be described as alignment geometry, line strings or points. It is possible to set the same type coding system for more than one of these.
The recommended type coding system in Inframodel exchange for 1) terrain is the Finnish Transport Infrastructure Agency type coding [Infra]. For 2) surface and 3) infrastructure objects, the recommended type coding system is the general InfraBIM type coding [InfraBIM]. Examples are given in sections 2 Base data and 3 Route planning.
In addition to the three main systems, it is also possible to define additional or alternative type coding systems, named as proprietaryInfraCoding (the name given here shall be used as prefix in later usage, see e.g. 2.1.3 Type coding)
"IM_codings" <Feature>
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name | optional name |
e.g. [1] | ||
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code | type code |
[IM_codings] | ||
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source | reference to source feature dictionary by name |
[inframodel] | ||
| coding systems <Property> | |||||
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label | [terrainCoding] | type coding system name for terrain source data |
value | [Infra] |
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label | [terrainCodingSourceRef] | source of terrain type coding system | value | e.g. [terrainCodingSourceRef="vayla.fi"] |
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label | [terrainCodingDesc] | description of terrain type coding system | value | e.g. [Finnish Transport Infrastructure Agency terrain coding] |
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label | [surfaceCoding] | type coding system for surface model |
value | [InfraBIM] |
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label | [surfaceCodingSourceRef] | source of surface type coding system | value | e.g. [surfaceCodingSourceRef="buildingsmart.fi"] |
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label | [surfaceCodingSourceDesc] | description of surface type coding system | value | e.g. [Finnish InfraBIM surface coding] |
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label | [infraCoding] | type coding system for general structures |
value | [InfraBIM] |
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label | [InfraCodingSourceRef] | source of infra type coding system | value | e.g. [InfraCodingSourceRef="buildingsmart.fi"] |
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label | [InfraCodingSourceDesc] | description of infra type coding system | value | e.g. [Finnish InfraBIM coding] |
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label | [proprietaryInfraCoding] | name of proprietary type coding system | value | e.g. by software X [proprietaryInfraCoding="X"] e.g. by organisation Y [proprietaryInfraCoding="Y"] |
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label | [proprietaryInfraCodingSourceRef] | source of proprietary type coding system | value | e.g. by organisation Y [proprietaryInfraCodingSourceRef="www.y.com"] |
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label | [proprietaryInfraCodingSourceDesc] | description of proprietary type coding system | value | e.g. by organisation Y [Y infra-coding] |
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<Feature> | schema documentation | |
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<Feature> | short example |
¶ 1.7 Application
The <Application> element describes what software was used to create the file. If the file has been created using several different applications, all are described by their own <Application> element.
<Application> definitions:
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name | name | e.g. [XML Spy] |
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desc | description |
e.g. [XML development environment] |
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manufacturer | manufacturer |
e.g. [Altova] |
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version | version | e.g. [2006] |
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manufacturerURL | manufacturer homepage |
e.g. [http://www.altova.com] |
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timeStamp | time stamp of last save |
date time [yyyy-mm-ddThh:mm:ss], e.g. [2009-10-19T17:21:05] |
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<Application> | schema documentation | |
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<Application> | short example |
¶ 1.8 Authors
Information of the author of the file is recorded in the sub-element <Application>.<Author>. It is possible to define several authors as separate <Author>-elements, each with the following information:
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createdBy | author name |
e.g. [Dave Designer] |
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createdByEmail | author e-mail |
e.g. [dave.designer@company.com] |
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company | company |
e.g. [Company] |
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companyURL | company homepage |
e.g. [http://www.company.com] |
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timeStamp | time stamp of last save | date time [yyyy-mm-ddThh:mm:ss], e.g. [2009-10-19T17:21:05] |
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<Author> | schema documentation | |
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<Author> | short example |
¶ 1.9 Feature Dictionary
The <FeatureDictionary> identifies the specification source of extensions used in the file, and the point of access to their documentation. The contents of <Feature> elements shall follow the source specification. LandXML-files in general may contain extensions from several different sources. In Inframodel file transfer, proper recognition and interpretation is required only for the extensions documented in this specification ( e.g. for the type coding systems used in an Inframodel file). The dictionary for Inframodel extensions shall be specified using <FeatureDictionary> element as shown in the table below. The name shall be unique, and always 'inframodel' for the dictionary of Inframodel extensions, and exactly the same value shall be set in every Inframodel <Feature> for attribute source (the <Feature> attribute code being labeled with IM_ -prefix). The <version> should match the version number of the Inframodel schema. Optional <DocFileRef> element can be used to provide the URI link to named external documentation where applicable feature code and property type values are described (EXTENSIONS page of this documentation, in the case of Inframodel feature dictionary).
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name | unique name of dictionary | [inframodel] | ||
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version | current version number | [4.0.4] | ||
| Document reference <DocFileRef> | |||||
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name | doc file name |
[Inframodel extensions] | ||
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documentation location | location |
[/inframodel/pages/extensions.html] | ||
Proprietary extensions can be used in addition to those specified in the Inframodel feature dictionary. Each source of such non-Inframodel extension specifications shall be identified as their own <FeatureDictionary> instance, with unique name. That name shall be set as the value of attribute source in every <Feature> according to that dictionary. Proprietary <Feature> instances should not have attribute code labeled with IM_ -prefix.
NB: When using proprietary extension for an <Element> that has a <Feature> in Inframodel schema using InframodelAbstractFeatureType (with annotation 'Inframodel'), an Inframodel <Feature> with the attribute code set to 'IM_proprietary' shall be first placed directly under the <Element>, and the proprietary <Feature> shall be placed under the Inframodel <Feature>.
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<FeatureDictionary> | schema documentation | |
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<FeatureDictionary> | short example |