JOSM Best Practices???

I just installed JOSM on my desktop computer (openSUSE Linux 12.2). I am an absolute beginner with OSM. Before I start downloading data and “playing with it”, I would like to have some idea about what expert users think are the “best practices” for newcomers. Getting started right makes things easier over time. The answer probably depends on what I plan to do with OSM. Here is a brief outline of where I would like to start:

I have quite a few waypoints and points of interest for central and western Texas that have been collected with a GPS or, more recently, the GPS on a smart phone (Blackberry 9300). Many have notes and pictures associated with them. Some are strictly private but others would be of general interest and should be shared with the world. Also, I have quite a few County (public) Road designations that do not show on current OSM maps. I would like to share that because the roads shown do not distinguish between Public and Private roads. Visitors do not want to trespass so the distinction is important and not obvious.

So the first “Best Practice” question is how to keep private information private and make public information public? Also, how do I avoid corrupting the public OSM while I am blundering around trying to learn? To begin, I want to work strictly offline until I am sure of the information and procedures.

Is there a “best practice” guide for what layers should contain what type of information? For example, what layer contains topo contour lines and what layer should contain street addresses or points of interest or satellite images? Can I put private information in one layer and information I want public in another and be confident that the private stays private?

Most of the routes or tracks I have are just waypoint to waypoint (is the OSM word “node” instead of waypoint?) instead of true tracking data. Is that accurate enough for OSM?

Also, is there a way to enter magnetic bearing information and convert it to true N/S bearings with the proper local declination calculations? I have some points of interest that are located by compass bearings from two or more GPS established waypoints. Some mapping software keeps files of local declinations to make these corrections. Does OSM?

Is there a guide that goes through the JOSM preferences with tips about what might be best for beginners? Often developers and very proud of their elegant bells and whistles (rightfully so) and forget that advanced features are just confusing to the beginner.

Any advice you might offer based on what seems to give newcomers most trouble would be sincerely appreciated.


Welcome to OSM! There are a number of questions, so I hope that others will jump in and help answer some as well.

OpenStreetMap does not contain layers; all data is stored in a single database and not separated. JOSM has the concept of layers which are generally only used as tools to assist with data editing.

We also do not store satellite images, contour lines or continuous altitude information - the GPS altitude readings are typically not accurate, and the SRTM info from NASA is much better.

If you have notes about track name, or whether the track is public or private, that is useful. To identify driveways on private property, just add the tag access=private.

Waypoint to Waypoint information by itself is not usually accurate enough to use unless you know that the trail between waypoints was exactly a straight line. But you might be able to see tracks or roads from Bing imagery that we are allowed to used to trace tracks from.

I’ll try to tackle a few more aspects that Mike has not addressed yet.

All the data in the main OpenStreetMap database itself is public. When using JOSM, you will work offline automatically until you explicitly upload your changes.

A distinction between private and public does exist for GPS tracks. Those can either just be loaded as a local file into JOSM, our you can upload them to the OpenStreetMap servers. In the latter case, you can still choose between different privacy settings. (Note that GPS data and the main OSM database are separate, with GPS data only being used to help you with manually drawing roads and other things, and that uploading GPS data is therefore also something different from the normal upload of changed OSM data.)

I think the best way to learn is still by making actual edits. Start out with small, easy changes to get used to the tools.

I believe the developers are aware of the problem. When you install JOSM and have not previously used it, it will be in beginner mode, and will remain so until you explicitly enable “expert mode”. Therefore, you already start out with a less feature-heavy view of JOSM.

Hello There, this page "LearnOSM, Beginners Guide" should be enough to get you started.

How do I load the SRTM data in JOSM? It doesn’t appear on the “imagry” drop down.

Some areas of far West Texas are sparsely populated with few real roads. Mountain peaks and canyons are the primary mapping reference. Even approximate relative elevation contours would be very helpful in pinpointing and mapping points of interest on the ground. You can see this in the OSM of Culberson, Hudspeth, Jeff Davis and Presidio Counties in Texas where I grew up.

The quote above also was very helpful to me in another way - It cleared the confusion about what is stored in OSM and what is not. The concept that the overlays are to refine the OSM basic map instead of becoming part of it answered a lot of my questions.

Thank you.

Hi - I don’t know of an SRTM data URL or plugin for JOSM, but the closest thing might be the “MSR Maps Topo” image layer. Typically, the countour or altitude data are used by separate programs to render maps, such as this nice Open Mapquest view: . The Mapquest renderer combined OSM data with elevation data when the map tiles were generated.

But I can see how the topo image layer would be useful when working with mountain trails.

Thank you very much. That is exactly what I was looking for. It also led me to:
which might be useful to others learning how to use JOSM.

It looks like that most of my work will be in JOSM saved locally because much of the information I want to map is of NO public interest (I doubt if anyone in Europe wants to know where my great grandparents are buried but my grandchildren do). Some of it, like my father’s hand drawn map and pictures of the traces of the stagecoach Route from Ft. Davis to Ft. Hancock or the location of pre-historic pictographs have historical value and should be shared publicly.

I now live in Brady, Texas. The OSM maps need updating. For example the old High School was demolished in 2012 after a new one was built. The Bing overlay shows the old school intact and the new one under construction. I think I can correct and upload those changes with information in the Beginners Guide you supplied.

Do I have the concept right that ALL of the changes I make to any JOSM file on my hard drive will be uploaded? If so, I would need separate files for public (upload) and private (save only). Is that correct?

Thank you very much.

Hello There,

No, no changes you make in JOSM are automatically uploaded to the database, until you click the green up arrow “upload all changes in the active data layer to the OSM server”. When the green arrow is clicked any warnings (errors/mistakes) are given. Then you get an upload box where a comment on the data for upload can be made, then you click upload changes. So you can see you get several prompts before data is uploaded. If a mistake is made data can be reverted or edited as long as its not to complex. start with small edits. When you go close JOSM or delete an edited layer you will be reminded about unsaved data, if it’s not needed click exit or delete now.

JOSM can store data locally to your hard drive, (1) either downloaded data, (2) edited downloaded data and (3) completely new data.

1 Download data, save it, can be overlayed on an image (JOSM imagery layer) but image is not saved.

2 Download data, do your own editing, save it, can be overlayed with an image (JOSM imagery layer) but image is not saved.

3 Open JOSM, click new layer (from file drop down), JOSM will not know where in the world you are. Open an image layer, pan/zoom to the area you want to work on. Start playing, I mean mapping. Save your data locally, it will not save the image layer, do not upload to the OSM database.

When you next want to work on that data open it again, load an image layer, off you go.

Just had to look at the procedures to remind myself, I think I’ve got it right, shout if you need clarification.

Regards Bernard

I was able to upload some minor changes from JOSM to the map of Brady, Texas (new schools built and the old ones demolished). The changes appeared on the public online maps in short order and look correct!

I have devised a plan for keeping separate files on my hard drive for data to be uploaded and data that is private. It seems like numerous small files is probably the best way to organize it. Is that a sound principle?

How is the best way to annotate map objects? On the public maps, it looks like we are strongly encouraged to use the “Presets” only. That seems wise just for the sake of simplicity, file size and multi-language use.

On my private maps (stored on my hard drive) I would like to embed or link to extensive documentation about the map objects. How is the best way to do that? The goal is to use the map as a foundation for a illustrated history of the area shown. Maybe a better concept would be to embed the map in a text document instead of the other way around. What do you think?

Again, thanks to everyone for prompt, helpful replies.



I took a look into your Changeset. Looks good for me.

  • Perhaps you can change this nodes to buildings (if only the facility is occupying the whole building) or areas.
  • Add additional address attributes (streetname, housenumber, phone etc.)
  • Add other touristic information (

Did you already found: ?

I am still learning how to do the basic things so just getting a single point created or moved is a big deal for me. I think the “Bulldog Stadium” point should be an area encompassing the football/track facility, baseball diamond and tennis courts. I will see if I can do that soon.

Also, there are enough gross errors that my time might be better spent correcting them rather than delving into details.

I tried to add a point of interest online but failed. It was the ruins of San Fernando Academy founded in 1882 to train school teachers. Nearby, and of interest to tourists, is the Pontotoc Winery and Vinyard. Two other wineries will open there this year. I apparently don’t know how to use the online Potlatch editor yet. I will learn in time. What would be the proper Presets for a winery and vinyard?

European tourists in particular are interested in the Heart of Texas Country Music Association events and local wineries. US visitors are more interested in game preserves and hunting. I will try to get those things uploaded as I have time.


What is the best practice for disputed locations?

As an example, the exact geographic center of Texas is located somewhere near Brady in McCulloch county. That makes “Heart of Texas” a favorite advertising slogan and something visitors want to see for themselves.

Up until about 2007, USGS said the geographic center of Texas was "located in McCulloch County, 15 miles NE of Brady.
Longitude: 99° 27.5’W
Latitude: 31° 14.6’N
These coordinates are NOT 15 miles NE of Brady but rather WNW of Brady, near the end of CR152.
USGS has since deleted the coordinates and left the written description on their website.

To further confuse matters, there is a roadside marker (about N31.387 W99.169) and observation tower on Hwy 377 describing the exact center as being “five miles northwest” on private property.

I am not asking this forum to resolve just where the exact center of Texas is, but this is probably not the only disputed location or boundary on earth. What is the “Best Practice” for dealing with them? How do you make it clear that there is some question about the location while still offering useful information?


I tried making the nodes into polygons around buildings or other areas. The “presets” appear different from what I expected. I suppose I have more learning to do.

Thank you for your help.


What is the Best Practice for Validation errors?

I loaded some GPS tracks to see how they aligned with the OSM and overlays. Then I made some minor changes to the OSM that resulted in validation errors (overlapping tracks, unnamed tracks etc). Is it better to just ignore the validation errors or try to decipher and correct them?

The tracks ARE unnamed “roads” through a city park that has a lot of vehicular traffic, RV hookups and campsites.

I think the overlapping tracks were already there. I am reluctant to revise other people’s work because I don’t know what I am doing… The changes I made were small changes to existing roads (mostly rounding corners by putting in more nodes).

I also notice that there are seemingly random areas outlined, line segments drawn and nodes sprinkled around but not labeled or connected to anything. Is it good practice to delete them or are they part of someone else’s work best left alone? I don’t know exactly where they come from because they don’t show in OSM, just in JOSM with an overlay. Also, sometimes when I am moving the mouse around, the City Limit boundaries will flash briefly and go away. I wouldn’t want to delete a line segment that seemed out of place but is actually part of the very irregular city boundary.

Are there guidelines about how to handle this type of thing? How can I tell if something is important or not?


If you modify data, then you will get validator messages even for pre-existing errors in that data. Not all validator errors and warnings do have to be acted on: Some can be handled later and some are even false alarms.

Overlapping tracks can actually be genuine problems, though, but if they did exist before your edits, I think it’s acceptable to ignore this for now. You can also post a link to the problematic tracks to the forums for others to look at.

When you don’t understand the purpose of some ways or nodes, you can look at the history of the object to find out where they come from. On, you can use the Data layer for that purpose. From JOSM, you can access built-in or web-based history views for a selected element from the ‘Edit’ menu.

Generally, ways should either have tags or be part of a relation, otherwise they are useless.

Thank you once again. That clears up a lot of questions. I am not experienced enough to correct existing errors so I think I will just leave then alone for now. Maybe later I will be able to figure out what is wrong and fix it.

I plan to gather more GPS nodes and tracks and upload them. Do the GPS tracks and waypoints get uploaded and stored or are they just for my use?

Will someone contact me if my contributions are not helpful (or even detrimental) to the project?