Changes between Version 63 and Version 117 of Help/Concepts/Object


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  • Help/Concepts/Object

    v63 v117  
    1 [[TranslatedPages]]
     1[[TranslatedPages(outdated=Member; Membership; Roles; Child and Parent not explained properly. Any need to split Tags into two parts ?)]]
    22
    3 = Objects - The basic building blocks of OSM data and maps =
     3
     4= Objects - The basic building blocks of OpenStreetMap data and maps =
    45
    56Please don't hurry reading this, you can consult this page again at any second.
    … …  
    78[[PageOutline(2-10,Table of Contents)]]
    89
     10
    911== Nodes, ways, and relations == #NodesWaysRelations
    1012
    1113=== Tags (also an OSM data primitive) === #Tags
    1214
    13 Tags provide meaning to the objects. Without them, any other object would be useless and meaningless. Each of ''three other data primitives'' '''can have multiple tags'''.
     15Tags provide meaning to the objects. Without them, any other object would be useless and meaningless. Each of ''three other data primitives'' **can have multiple tags**.
    1416
    15 [=#presets Often tags used in combinations; '''usually these combinations can be found] in [wiki:Presets presets]'''. But it may be true that tags you need to use are not in presets and you need to know them first.
     17[=#presets Often tags used in combinations; **usually these combinations can be found] in [wikitr:/Presets presets]**. But it may be true that tags you need to use are not in presets and you need to know them first.
    1618
    1719Simplest example is [osmwiki:Key:drinking_water drinking_water=yes] - it is present globally and can be applied to every object that provides water. Other example is [osmwiki:Key:leaf_cycle leaf_cycle]=* of trees, it will have less coverage globally (as trees do not grow just everywhere).
    … …  
    2224
    2325=== Nodes (also an OSM data primitive) === #Nodes
    24 [[Image(source:trunk/images/data/node.png,20,bottom,margin-right=15,nolink)]] A **node** is an individual point with a defined position. ''With respective tags'' it can be used to indicate shops, benches, individual trees or points of drinking water.
     26[[JOSMImage(data/node,24,bottom,margin-right=15,link=)]] A **node** is an individual point with a defined position. ''With respective tags'' it can be used to indicate shops, benches, individual trees or points of drinking water.
     27
     28Only nodes have [wikitr:/Help/Concepts/Coordinates Coordinates] in the OSM data model. Ways and relations simply refer to nodes.
     29
     30==== Common nodes ====
     31
     32Nodes can be re-used between multiple ways. Multiple ways can refer to a single node (common node).
     33
     34A practical meaning of this is demonstrated at the [wikitr:/Help/Action/Draw#Commonnodes Draw Nodes] page. The [wikitr:/Help/Action/MergeNodes Merge Nodes] tool can be used to create common nodes.
    2535
    2636=== Ways (also an OSM data primitive) === #Ways
    27 [[Image(source:trunk/images/data/way.png,20,middle,margin-right=15,margin-bottom=5,nolink)]] A **way** is a sequence of nodes. OSM **way** used to represent linear objects, ''with respective tags'' it can used to describe: a river bank, tree row, kerbs in the streets (among other uses).
     37[[JOSMImage(data/way,24,middle,margin-right=15,margin-bottom=5,link=)]] A **way** is a sequence of nodes ([https://en.wikipedia.org/wiki/Polygonal_chain a "polygonal chain" from ordinary geometry]). OSM **way** used to represent linear objects, ''with respective tags'' it can used to describe: a river bank, tree row, kerbs in the streets (among other uses).
    2838
    29 ==== Areas ==== #ClosedWays
    30 [[Image(source:trunk/images/data/closedway.png,20,middle,margin-right=15,margin-bottom=5,nolink)]] If a **way** is closed, i.e. if the last node is the same as  the first node, it is also called an **area**. Old term for this is ''Closed Ways'' (it is still present at wiki, used in software and by some mappers; other part uses "geometry" when talking just about shape of the objects, without tags).
     39==== Direction ====
     40Since nodes are ordered in OSM; every way in OSM has a direction. This gives us possibility to add tags (details about object) such as [osmwiki:Key:conveying conveying=*] - to specify direction of escalators and moving walkways or [osmwiki:Key:incline incline=*] which can be used toghter with roads and footways. There [osmwiki:Category:Way_Direction_Dependent more examples] and we can't cover them all.
    3141
    32 Sometimes single area is not enough to represent an object (for example, a lake with an island in it), then you have to use a [wiki:Help/Concepts/Object#typemultipolygon multi-polygon]
     42**Note**: Rendering of direction in [wikitr:/Help/MapView MapView] can be set in Preferences under [wikitr:/Help/Preferences/DrawingPreference OSM Data].
     43
     44==== Segment ====#Segment
     45Is **a fragment between two consequent points of the way** ([https://en.wikipedia.org/wiki/Line_segment "line segment" from ordinary geometry]). This is not a part of OSM data model, but users often distinguish because of tools than operate on segment level (rather than on complete way); please, distinguish a segment(s) from complete "way"s.
     46
     47**Note**: Rendering of segments in [wikitr:/Help/MapView MapView] can be set in Preferences under [wikitr:/Help/Preferences/DrawingPreference OSM Data].
     48
     49==== Areas ==== #Areas
     50[[JOSMImage(data/closedway,24,middle,margin-right=15,margin-bottom=5,link=)]] If a **way** is closed, i.e. if the last node is the same as  the first node, it is also called an **area**. Old term for this is ''Closed Ways'' (it is still present at wiki, used in software and by some mappers; other part uses "geometry" when talking just about shape of the objects, without tags).
     51
     52Sometimes single area is not enough to represent an object (for example, a lake with an island in it), then you have to use a [wikitr:/Help/Concepts/Object#typemultipolygon multi-polygon]
    3353
    3454=== Relations (also an OSM data primitive) === #Relations
    3555
    3656==== In most cases you don't need them ====
    37 
    3857If some object can be represented with single ''node'' or ''way'' and ''multiple tags supported by software'', then there is no need in relations. But there are some rare cases where it is theoretically and practically impossible ''only with nodes, ways and tags'' (ex. turn restrictions, will be covered below).
    3958
    40 ==== Simple explanation ====
    41 [[Image(source:trunk/images/data/relation.png,20,middle,margin-right=15,margin-bottom=5,nolink)]]  A **relation**:
     59This means **you can [#Tags1 skip this big "Relations" section], until you decide to add or edit a relation**.
     60
     61==== Simple explanation ====#SimpleExplanation
     62[[JOSMImage(data/relation,24,middle,margin-right=15,margin-bottom=5,link=)]]  A **relation**:
    4263* is a sequence of other objects (nodes, ways and relations)
    4364* as other objects (node, way) - every relation can have their own "tags"
    4465* can be used as members in other relations (nested or hierarchical structures)
    45 * tag type=* used to define one of [http://wiki.openstreetmap.org/wiki/Types_of_relation many types of relations]
     66* tag type=* used to define one of [osmwiki:Types_of_relation many types of relations]
    4667
    4768Additionally, each object participating in a **relation** can be assigned a **role**, for instance "via" node and "from", "to" ways in type=restriction relation.
    4869
     70[wikitr:/Help/Relations Relation Help] covers the most basic tools to create relations in JOSM ([wikitr:/Help/Dialog/RelationList Relations window], [wikitr:/Help/Dialog/SelectionList Selection], [wikitr:/Help/Dialog/RelationEditor Relation editor]).
    4971
    5072==== Most popular types ====
    5173
    52 ===== type=multipolygon =====
     74===== type=multipolygon =====#typemultipolygon
    5375
    54 A water object (natural=water), a building (building=*) or administrative boundary (admin_level tag).
     76A water object ({{{natural=water}}}), a building ({{{building=*}}}) or administrative boundary ({{{admin_level=*}}} tag) usually consist of the  multiple spatially separated parts belonging to the one object. More importantly, each of these parts can have exclusions ([https://en.wikipedia.org/wiki/Enclave_and_exclave enclaves/exclave] or simply islands or swamps in the water basins).
    5577
    56 (stub)
     78* Parts are created using "{{{outer}}}" role. ''Each multi-polygon should have at least one outer part''.
     79* Holes inside parts - using "{{{inner}}}" role. ''Each part can have from 0 to N holes''.
     80* Ways that form a ring where all ways are connected between each other using common nodes (JOSM will warn you about mistakes during validation)
     81* Rarely, holes can be nested. If nesting is more complex than ''single outer'' and ''single inner ring'', role swapping can continue: outer-inner-outer-inner-...
     82* Outer and inner rings shouldn't have common nodes (but validator will warn you about this and other mistakes)
     83
     84Multi-polygon specific tools:
     85* [wikitr:/Help/Action/CreateMultipolygon create a multipolygon]
     86* [wikitr:/Help/Action/UpdateMultipolygon update existing multipolygon]
    5787
    5888===== type=route =====
    5989
    60 Used to describe bus routes and train routes along other transportation services.
    61 (stub)
     90[osmwiki:Relation:route Route-Relation] describe common routes for all kind of transport modes and transportation services like [osmwiki:Tag:route=road roads], [osmwiki:Tag:route=bicycle bicycle], [osmwiki:Tag:route=hiking hiking], [osmwiki:Public_transport public_transport] or even electric [osmwiki:Tag:route=power power lines]
    6291
    6392===== type=restriction =====
    6493
    65 Can used to describe turn restriction according to signs and road marking. JOSM has a plug-in to support this type of relations: http://wiki.openstreetmap.org/wiki/JOSM/Plugins/Turnrestrictions
     94Can be used to describe turn restrictions according to signs and road marking. JOSM has a plugin to support this type of relations: [osmwiki:JOSM/Plugins/Turnrestrictions Turnrestrictions plugin],[osmwiki:Relation:restriction#Examples Examples]
    6695
    67 http://wiki.openstreetmap.org/wiki/Relation:restriction#Examples
    6896
    69 == Tags ==
     97== Tags ==#Tags1
    7098More precisely, a **tag** is a name/value pair assigned to an object. If we write `foo`=`bar` we mean ''The tag with key foo is assigned the value bar''. Here are some examples:
    7199* `name`=`Main road` assigned to a way. This tag indicates that the name of the way is `Main road`.
    … …  
    87115Assigned to a way, this set of **tags** indicate, that the way represents a road in a residential area with name ''Main road'' (the German name be ''Hauptstraße'', the English name, which in this example equals to name, is ''Main road''). Speed is limited to 30km/h and heavy goods vehicles (hgv) are not allowed. Furthermore, it's a one way street.
    88116
    89 In the [[Image(source:trunk/images/dialogs/propertiesdialog.svg,18,middle)]] [Dialog/TagsMembership Tags/Membership Dialog] you can assign tags to an object, remove tags from an object, or edit assigned tags.
     117In the [[JOSMImage(dialogs/propertiesdialog)]] [wikitr:/Help/Dialog/TagsMembership Tags/Membership panel] you can assign tags to an object, remove tags from an object, or edit assigned tags.
    90118
    91 == Object ids ==
    92 The OSM server assigns each object a unique number, the **object ID** or **OSM ID**. A new object doesn't have an ID (it's ID is 0) until it is uploaded the first time to the OSM server.
    93 * Under **''Preferences -> [[Image(source:trunk/images/preferences/display.png,18,middle)]] [Preferences/Display Display Settings] -> Look and Feel''** it is possible to en- or disable the display of objects ids in the toggle dialogs.
    94 * With **''File -> [[Image(source:trunk/images/downloadprimitive.png,18,bottom)]] [Action/DownloadObject Download object ...]''** it is possible to download **objects** by Ids.
    95 * **''View -> [[Image(source:trunk/images/info.png,18,bottom)]] [Action/InfoAboutElements Advanced info]''** opens separated windows with informations about selected objects in text format.
    96 * **''View -> [[Image(source:trunk/images/info.png,18,bottom)]] [Action/InfoAboutElementsWeb Advanced info (web)]''** opens the **objects' pages** of selected objects on the [osmwww: OSM website] in your web browser.
     119
     120== Technical properties ==
     121
     122=== Object id ===#ObjectId
     123The OSM server assigns each object a unique number, the **object ID** or **OSM ID**.
     124
     125In JOSM, a new object doesn't have an ID (its ID is 0) until it is uploaded the first time to the OSM server.
     126* Under **''[[JOSMImage(preference)]] [wikitr:/Help/Action/Preferences Preferences]''** (or **''`F12`''**) -> [[JOSMImage(preferences/display,24,link=,middle)]] **''[wikitr:/Help/Preferences/Display Display]''** it is possible to en- or disable the display of objects ids in the windows.
     127* With **''File -> [[JOSMImage(downloadprimitive)]] [wikitr:/Help/Action/DownloadObject Download object ...]''** it is possible to download **objects** by Ids.
     128
     129**Note**: The display of object ids in the [wikitr:/Help/Dialog/SelectionList Selection List] can be set in Preferences under **''[wikitr:/Help/Preferences/Display Display]''**.
     130
     131
     132=== Object versions and history ===#Objectversionsandhistory
     133Version numbers (versions) were introduced to simplify wiki-style editing. Unfortunately, to track changes to ways/relations you need to use more complex tools than simple comparison by version number.
     134
     135* Contents of the relation can change without change in version or id of the relation (a way can be changed, a node can be changed, a child relation can be changed).
     136* Contents of the way can change without change in version or id of the way (a child node can be moved back and forth several times, but id of the way may stay the same).
     137
     138But you can always track complete history of one node based on history.
     139Also, you can use time sliced data (region extracts by date) to inspect how objects were changing (and refer to object id and point in time from the database).
     140
     141**Note**: The display of object versions in the [wikitr:/Help/Dialog/SelectionList Selection List] can be set in Preferences under [wikitr:/Help/Preferences/Display Display].
     142
     143==== Information about latest version ====
     144* **''View -> [[JOSMImage(info)]] [wikitr:/Help/Action/InfoAboutElements Advanced info]''** (or Keyboard shortcut:**''`Ctrl+I`''**) opens separated windows with informations about selected objects in text format.
     145* **''View -> [[JOSMImage(info)]] [wikitr:/Help/Action/InfoAboutElementsWeb Advanced info (web)]''**  (or Keyboard shortcut:**''`Ctrl+Shift+I`''**) opens the **objects pages** of selected objects on the [osmwww: OSM website] in your web browser.
    97146
    98147Alternatively, you can browse the objects directly by entering following address in your web browser:
    … …  
    102151}}}
    103152
    104 == Object versions ==
    105 Each object has a **version**. The **version** is incremented whenever the object is uploaded to the server and the OSM server not only stores the most recent version of an object, but it's complete **history**.
     153==== History of the object ====#ObjectHistory
     154Each object has a **version**. The **version** is incremented whenever the object is uploaded to the server and the OSM server not only stores the most recent version of an object, but its complete **history**.
    106155
    107 * **''View -> [[Image(source:trunk/images/dialogs/history.png,18,bottom)]] [Action/ObjectHistory History]''** opens the History Browser. The History Browser will show you the **versions** of a particular object.
    108 * Alternatively, **''View -> [[Image(source:trunk/images/dialogs/history.png,18,bottom)]] [Action/ObjectHistoryWeb History (web)]''** opens a page on the [osmwww: OSM website] in your web browser which displays the object history, too.
     156* **''View -> [[JOSMImage(dialogs/history)]] [wikitr:/Help/Action/ObjectHistory History]''** (or Keyboard shortcut:**''`Ctrl+H`''**) opens the History Browser. The History Browser will show you the **versions** of a particular object.
     157* Alternatively, **''View -> [[JOSMImage(dialogs/history)]] [wikitr:/Help/Action/ObjectHistoryWeb History (web)]''** (or Keyboard shortcut:**''`Ctrl+Shift+H`''**) opens a page on the [osmwww: OSM website] in your web browser which displays the object history, too.
    109158
    110159----
    111 Back to [wiki:/Help Main Help]
     160Back to [wikitr:/Help Main Help]