User:Detectist/OSM Mapping (Using Potlatch) for Dummies

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OSM Mapping (Using Potlatch) for Dummies

  • Here are some tips for new starters. Importantly, these notes include a little etiquette! The notes below are based on Potlatch. If you are whiz-bang with computers and mapping, go for JOSM or one of the other options.
  • There is much more but this note is really for the very beginners.
  • The basic steps are
  1. Collect data using your GPS
  2. Clean up the data removing extraneous wanderings
  3. Upload your data following the procedures below
  4. Edit your data on Open Street Map (, especially checking for other Gps traces in the same area
  5. Add tags

1. Collecting Data

  • When using your GPS to record a track, it is important to switch off “Lock on road” or “Snap to road” on your GPS. If you don’t, you will copy only the map, not where you’ve been!
  • Besides recording tracks, you can collect data about where you are and what you are mapping, if you have the time and inclination. For example, you can note the street names, road and track surfaces, stores, museums, etc., in your GPS or other recording device (or in writing if you're keen).
  • It is important to remember that you are creating original intellectual property and giving that data to OSM. You are not supposed to copy from another map, even for street names! I mark waypoints and some of these actually are points of interest (POIs - which can also be useful for sites such as too!).
  • Have a look at an area on Open Street Map (OSM) that you are familiar with. See what others have done in terms of length of track and POIs.

2. Clean up your tracks before you upload them.

  • Remove extraneous data: For example, if you wander around at the start of a track, remove the excess. Similarly, if you stop for lunch and move along viewpoint edges for an even better photo etc and then wander off into the scrub for some relief, the world does not need to see everywhere you’ve been. The info uploaded must still be “raw,” in other words, actual tracks, but a bit of tidying is fine.
  • Break up your intended uploads into smaller files: If you make too many errors in editing once your track has been uploaded then it isn’t as much of a pain to delete, reload and retrace.
  • Be careful that your editing program does not alter or remove the timestamps as OSM may reject the trace. Some people load the entire trace from their GPS as OSM will remove some of the extraneous data before it is published in a downloaded map.

3. Upload your data

  • If you want just to submit a track without doing anything else, that is all right. Eventually someone will trace over. (NOTE: Tracing is easy, if yours is the only track. You just click and drag a line to follow the thin wobbly green/bluish line (which is your track), clicking for each main movement away from a straight line. You might need a few nodes (ie trackpoints) for bends and turns.)
  • Upload your track/trace (i.e., a gpx file) at by selecting “See just your traces, or upload a trace”. Then, make it identifiable. You may have to wait a bit for your track to show up. At that point, if you wish, you can go to the next step.

4. Edit your data

  • Open your trace through the same tab, that is, GPS Traces (, then select, “See just your traces, or upload a trace” option and select the trace you wish to edit. Choose the “edit” tab, then tick the box that says “convert GPS track to ways” on the “edit with save” option. Do NOT edit live.
  • Check carefully to make sure Potlatch is ready. DO NOT start making additions/changes to the map until the message in the top right corner that says “loading data” goes away. Similarly, wait for the message at the bottom left of the map that says “transferring data” to look as though it has stopped too. Have patience.

At this point, you are a lot better off having the opportunity to review your edits before you save them.

  • Remember what others have done when you looked at your local area to see what traces have been made of local tracks, for example, what POIs were included, how the traces are described (see tagging points below).
  • Editing where there are multiple traces: This is important. If you are editing and your mouse pointer changes from a nib to a finger, that indicates that someone has been there before you. Similarly, if there is a coloured line in addition to yours, then someone has been there before you. To see all the traces for the area where you are working, hit the second left bottom button in the bottom left area (looks like a mobile phone) with a mouse click or press the “G” on your keyboard to see all traces. To see only your traces, hold “Shift” then press “G.” Be careful here! You do not want to change someone else’s trace, particularly if it’s outside their front door! If you think a change is necessary go into history of the way (bottom left of screen under the “Advanced” (editing options) button) and look at the traces, closely – take care not to revert the way to a previous version. Sometimes it may be better to leave your track there and others can see it and if necessary someone else will eventually check out any discrepancy. (The “History” tab at the top of the map screen isn’t working properly it appears.)
  • Sometimes the track someone else has done is a trace of satellite imagery (see “Add tags” below) (Landsat and Yahoo Imagery are OK to use, but NOT Google). If you have used a GPS to record your track, it is likely (but not 100% certain) that your trace will be more accurate than a trace of satellite imagery, but still ask the mapper who did the earlier work. Try to check the history.
  • If you are fairly certain it will be OK to make a change and you need to add a few twists and turns in the trace, this can be done by adding points to the existing trace, by shift clicking on the trace at the spot you want to move, and then dragging the new spot to the new position.
  • Deleting your mistakes: This is best done before you save, but can be done afterward too. Press “Z” to undo the changes you have made (unless you have saved). In cases where I have really stuffed it up, I delete the entire track, go back into Mapsource (or equivalent GPS track and map editor), fix, then upload again. If yours is the only information it is particularly important that you reload.

5. Add tags

  • Tag basics: A [[tag] adds information about ways and points on the map. First, become familiar with the system for tagging using the Map Features section of the OSM wiki. Read through the lists. You will see there are upper level categories of tags, called “keys” and subcategories, called “values.” These give a lot of flexibility, but try to follow the standard ways to represent common features, such as “highways” (the “key” for many different kinds of ways) and “residential” (the “value” for a typical residential street).
  • Potlatch helps you find the correct tag.

General rule: Type all key and tag names in lower case!

  • If you create a new point or click on an existing one, Potlatch opens what looks like a small grey box under the lower left edge of the map.
  • On the top line there is an icon in light grey. Click on the icon to move from one group of keys to another. For example, if you see the car icon, you will see “(no preset) beside it and a small down arrow. You can click on the small down arrow to see some choices of keys.
  • If none of these fit, you can click on the small “+” sign to the far right below the map. That adds a line below the car icon with the word “key” highlighted. You then click on the word “key” and start typing the key for the tag, such as “highway.” Potlatch recognises the first letter you type and immediately gives some choices, such as “highway” and “historic.” Choose the one that fits.
  • You can add more data by adding more lines. For example, if you choose “store” as a key and “convenience” as a value, Potlatch will also add a key “Operator.” There you can add the name of the chain, if that applies. You also can add a name by clicking the “+” sign to create a new line, typing “name” in the “key” location and the name of the store as the value.


  • When tagging, keep handy two critical references: Map Features, which lists typical tags for most features, and (in my case) Australian Tagging Guidelines. Printable versions can be obtained from the toolbox on the left hand side of the OSM window.
  • When you tag, make sure to put in the source of your information. GPS is the first option, there is also survey and few others. I now use a combination of “source=survey” and “survey=gps”. This gives people some clarity and assurance of the validity of the information collected. Some tags do not seem sensible sometimes. Give it time and think about all the variations that might occur, and you’ll come to understand that perhaps some aren’t as silly as they seem in the first place, e.g., for bushwalking tracks the tag is “highway=footway” and for track sections along fire trails “highway=track.” Have a think about it. When I think a tag is not quite right, I add a description tag, so I can add a few extra words. Hopefully a more experienced OSMer will understand the message and apply the “right” answer. If yours is the only information, then it is as right as it can be and much better than no information.

Interestingly, sometimes, the options for tagging in Potlatch may differ from the Wiki description. I suggest that you use the Wiki.

  • When positioning POIs, zoom in to see if you are the only person who has done it and make sure you put it in the right place. In more sophisticated programs than Potlatch, like JOSM and Merkaartor, you can put in latitudes and longitudes for POIs. Potlatch provides symbols for some POIs – just click and drag them to the right position.
  • When you save traces, again, be patient. Your changes will be saved and will show up. It may take a little while. OSM is a worldwide accessible site and has peak periods, such as the ends of weekends and Mondays etc. For example, a change may take 30 minutes or so to show up in the Osmarender option (see the “+” sign upper right area), but it may not show up in the “View” tab for a week (regeneration happens each Thursday, apparently). Some POIs/nodes may take a fortnight to show up.


I wish to thank RRover (Darylr) and Drlizau who are both members of GPS Australia and OSM. They have been very patient with me and have provided a lot of assistance to me in my OSM mapping and in the writing of this guide. I would also like to thank techlady (Charlotte Wolter) not only for adding some good material particularly in the tagging section but also for applying a keen writer’s eye – it has helped a lot!

Techlady has advanced this guide to include more information on editing. This new Guide will also be posted on the Wiki shortly.