JOSMことはじめ

言葉の定義

"ノード (node)" は点、"ウェイ (way)" は複数のノードをつなぐ線を意味します。このことは、"ウェイ" は単に複数のノードをつなぐ線一般を刺しており、道路などの現実的なウェイ（道）だけをさす言葉ではないことを意味します。"リレーション"はウェイとノードを順番に並べた物で、要素のコンテナと言える物です。"領域 (Area)" は終点が接続されたウェイの呼び名であり、特別な存在ではありません。

道やトラック、パスが曲がっているときにはたくさんのノードを置いて短いウェイでそれらを接続します。ウェイは方向を持ち、多くのタグではそれが意味を持ちます。一方通行 (oneway=yes) ではそのまま通行方向となります。他のタグではウェイの右側と左側を区別します。（海岸線など）

JOSMを開始する

JOSM は Java で書かれたプログラムであり、.jarファイルを実行して起動します。起動方法は各OSで異なりますので、JAVAプログラムに詳しい誰かに聞くか、インストール方法を読んでください。

JOSMが起動すると、JOSMの新しいバージョンでの変更点についての情報を書いたウィンドウが開きます。起動するたびにこのページの内容をチェックするように心がけてください。重要な変更があるかもしれません。

次に、データをダウンロードします。もし編集したいエリアのGPSトレース（GPXファイル）があるときには、直接それを開いてもかまいません。ファイル->開くで開くと、そのファイルの地域を表示します。緑色のダウンロードボタンを押すと、そのエリアのデータをOSMのサーバ (openstreetmap.org) からダウンロードします。場所は地図から選んだり、地名で検索できます。一度にダウンロードできる範囲には限りがあるので注意してください。

An alternative is to download existing GPX points from the OSM server. In order to start this process you will need to know the latitude and longitude coordinates of the relevant area. The easiest way to do this is to use the download dialogues slippy map in the first tab. You can browse this map, zoom in and out and mark the area you're interested in. Read more on the download dialogue.

Editing in JOSM

JOSM is an offline editor which means everything you do won't be visible for anyone else until uploading it to the server. This makes it possible to experiment and repeatedly moving, tagging, adding and deleting elements without breaking anything. Subsequential actions on a single element will go into the database as a single modification when uploaded.

The first step of actual editing is to add a node to the OSM data where there will be a junction or a significant change in direction. To add a node, highlight the node button, either by clicking the 2nd button in the left menu bar, or by hitting the "A" key on the keyboard (the 2nd button should then be highlighted). Move the mouse cursor over your GPS track, and left click it wherever you want a node to be. A white dot (a selected node) should appear and a rubberline span from that dot to the mouse cursor. As you create subsequent nodes the earlier nodes will be shown as yellow dots.

A series of joined nodes forms a way.

Ways on their own are not of much use unless they are tagged to say what they represent. ​Map Features shows all the current key value pairs which could be used on a way. Ensure the properties pane is open on the right hand side of JOSM, the 8th button on the left (an icon with a wrench over a document) should be highlighted. If not click that button or hit "Alt+Shift+P". The properties pane has three buttons: a plus sign with "Add" next to it, then "Edit", then "Delete".

Editing properties refers to all the currently selected, i.e. highlighted, elements (nodes and ways). To select anything you must be in select mode which can be switched into by clicking the first of the left hand icons or hitting the "S" key. Ensure your new way is highlighted, then click the "Add" button, a dialog box will appear and you will be asked to select a key and a value. Type in the key/value pair which represents the way you are creating, e.g. for the key type "highway" without the quotes, and for value type "secondary" again without the quotes. Now click OK. You have now tagged your way.

Uploading to OSM

If you are happy with all that you have done then you need to upload this to OSM server. Click on the green up arrow .

JOSM will give you an overview on the elements it's about to upload. You're also asked to provide a short freetext summary of your edits. This description will be saved with your data on the server and serves information purposes like for example the ​Recent Changes list.

With a click on "Upload changes" your data will be uploaded and visible for everyone else.

See Upload to OSM for further informations on uploading.

Conventions

A couple of other points about creating ways.

1) Dual carriage ways should be drawn as two separate parallel ways, with each carriage way being a different way.

2) If a street is one way (including the individual carriageways of a dual carriageway) the way should be drawn in the direction of travel.

3) The key / value tagging is case sensitive, all keys should be entered in lower case.

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