OpenStreetMap

Xvtn's Diary

Road Curve Mapping Tips

Posted by Xvtn on 24 May 2023 in English.

Don’t Overdo It

Use as few nodes as possible, but as many as necessary. This makes it much easier for later mappers to improve or update things.

Fidelity

Keep Consistent Distance Between Nodes

Makes rendered maps look much nicer :)

Consistent

Follow Road’s Centerline

Center it

Do you disagree? Any other tips? Leave a comment.

Discussion

Comment from nickjohnston on 25 May 2023 at 16:59

I broadly agree, but would like to point out that for those willing to use JOSM, UtilsPlugin2 provides the very useful Circle Arc tool. I use it a lot.

I like iD. Without it I most likely would have never started editing OpenStreetMap. But I advise people to learn JOSM. The investment will soon pay back.

Comment from Xvtn on 25 May 2023 at 17:15

Great tip! It seems there’s a JOSM plugin for everything. Obviously it’s the more powerful option for editing, but after trying to get used to it several times I can’t seem to get over that initial wall of unfamiliarity. I suppose one of these days I should make myself switch over and reap some of the benefits you describe…

Comment from philippec on 26 May 2023 at 09:40

If you have an official map, maybe the official centerline is the best.

Comment from Exe19 on 29 May 2023 at 09:44

I’d add a sub-point to “Keep Consistent Distance Between Nodes”: node spacing should be proportional to curvature:

If the curve is tight segments should be shorter,
if it’s gentle they should be longer and
if the segment is straight as laser beam then it should have no intermediate nodes unless something else requires it

That way the angular spacing is more consistent and we use nodes where they are the most useful.

Comment from philippec on 29 May 2023 at 09:47

I hate when the map in my region has a childish look.

Comment from Rovastar on 27 June 2023 at 04:00

I completely disagree with the don’t overdo it.

Go as detailed as possible in general let’s say a meter or so max level (dependant on the curvature) the example you gave as ‘too detailed’ I think is fine. Your ‘perfect one’ was IMHO terrible and needs at least double the amount of points.

Your reasoning for not adding more points is that someone may need to update in the future. My question is why? The road in question will likely stay that way for decades and a really well mapped curve will not need any changes made to it for all that time. What are they going to update? If the road changes significantly then the whole thing will need to be remapped anyway.

I say with time permitting map it as detailed as you can. The result will be there for a long time.

(I have other issues with that curve too it is to far aligned to one side it should be in the middle of the road and the connecting road should be more curved to reflect what the road….but I digress)