wetlands marshes swamps

I’ve been filling in some of the wetlands in Rockland County NY. Not knowing better I initially tagged many of these areas as natural:marsh Later on I was reading on the wiki map features page that natural:marsh should no longer be used and instead use natural:wetland and then the appropriate wetland such as swamp or marsh. So I guess my question is why potlatch does not call up these options by default? I only use potlatch so far for it’s ease of use. So it would be easier if the template classes and types, as well as the tag keys and values matched what is currently suggested by default instead of typing these features in.

I, recognize, of course, that the reason potlatch isn’t working this way is that it takes time for another volunteer to modify the program.


I submitted a ticket. thanks.

new question: I trying to do something with the map graphics. I see the graphic for wetlands, and I see the graphic for water. My edits will either show one graphic or the other, a marsh symbol or a blue field. I see elsewhere on the map that there is a way to overlap so that the marsh symbol show up on top of the blue field so both are visible. I would want to do this is wetland areas that are particularity well flooded. So is there a method in potlatch to get the marsh symbol to show up over the blue water?

Can you post a permalink so we can see the examples too? (bottom right of the map)

It’s ok, I found one here http://www.openstreetmap.org/?lat=33.75664&lon=-78.85557&zoom=16&layers=B000FTF

Potlatch is an editor of the OSM database, the database is rendered by the likes of Mapnik (the default) and Osmarender. The two are independent of each other. Therefore there is nothing you can do “in Potlatch” to make things render one way or another.

The fact that the marsh symbols are rendered above forest but below water is a feature of Mapnik. If you switch to Osmarender (the blue + on the upper right hand edge) you will see that it renders the marsh symbols above both forest and water, which I think is what you were after.

If you’d like to request a change to Mapnik, log a ticket at http://trac.openstreetmap.org/

Be aware that there are other renderers though, and they may handle these differently. See http://wiki.openstreetmap.org/wiki/Renderers

But thanks for pointing this out, I didn’t know you could overlap marshes like this! :slight_smile:


zoom in at that location and you see this:
the marsh is rendered over the water. so how do I make my edits look like this too?
of course, just to the east is another marsh that got overlayed by the water.
I want to recreate the look of the marsh on the left/west.

Umm, yes, I think that might be a bug!

The layering rules should be consistent in Mapnik and they would not seem to be in this case. There is nothing that you can do within Potlatch about this and I suggest you raise a ticket.

Sorry, it’s superficially attractive but this isn’t the right way to do it. Marshes are not lakes, lakes are not marshes. Polygons should not overlap one another.

flooded=yes. OK, I’m kinda kidding but essentially what you are trying to do is describe a particularly wet-wetland, to define a difference between a swampy area that is perhaps seasonal and an area which is permanently inundated, right?

What you need to do is to decide how best to describe that and to use the appropriate wetland or invent one if you can’t find anything appropriate. It won’t render on the Mapnik layer but you could request that it is rendered and/or render your own map to show it if that’s what you want/need.

Hope this helps. :slight_smile:

I rather like it, actually. Something can be a meadow and boggy, or a wood and boggy, or a nature reserve and boggy. This feature describes what’s on the ground perfectly.

I have mapped a number of reedbeds (one of the wetland categories) which are distinctly located in lakes: [South Conneries Reedbed](http://www.flickr.com/photos/richard_on_flickr/3933785300\). No doubt in 20 years time they may be well enough established (assuming the geese dont get through the protective fencing, to remap the border of the pond. There is also the characteristic Schwingmoor vegetation type where a mass of wetland vegetation is floating on a water surface. Each of these seems an entirely valid reason for having overlapping natural=* polygons: and much easier to use than some kind of cartesian product of categories which represent potential overlapping habitat classes.

One thing that takes time is seeing how my edits appear on the map. And then even longer to see how it appears on my GPSr. So as far as creating the look of a flooded wetland, whether it is proper to do so or not, I see that it often happens when one of the overlapping polygons is a coastline or riverbank. I see many flooded wetlands on the Atlantic Coast near the Outer Banks, where this would make sense. I did try to create one closer to my home, along the Hudson River in Haverstraw, and it seems to render well. In the long run, I might improve this area, while keeping Alex’s comments in mind that it might be best to avoid overlapping. I find it is far more difficult to purposefully overlap and have the results look satisfactory when trying to overlap inland natural water like smaller lakes with marshes.

One reason I am even concerned with this is for the purpose of hiking. With OSM, I like how there is a clear definition between what make a stream and what makes a river, when it comes to rendering the map. I read that a stream can be jumped over. You can basically cross it without getting real wet. A river, and you might want to think about finding a proper way to cross, such as a footbridge. So I guess I was kinda thinking along the same lines when it came to wetlands. While for the environment’s sake, I’m not encouraging anyone to go plodding through sensitive marshland, but I guess my original thought was that the wetland graphic on the map might indicate one degree of passibility while the multipolygon look of flooded wetland would be a good indication that it is time to get a boat.