[talk-au] Mapping tree cover

Fri Oct 8 08:43:04 UTC 2021

Picking just Adam's question about mapping after a fire. [I also very 
much support the idea that OSM ways should ideally have only one primary 
tag and so agree that natural and boundary does not go together.]

I went through a similar self-dialogue where I am now in Sweden as to 
what to with clear-cut areas. My conclusion was just ignore them and 
still map as wood/forest. I think the same applies here.

It remains woodland, just in a special state. And it opens a two cans of 
worms: When does it stop? (Natural regeneration, replanting). Highly 
impractical given the wildly different dates on imagery commonly 
available to us.

That said, cutting and fires have a huge impact on navigation markers, 
aesthetic enjoyment of the countryside and more so it would be "nice" to 
see some sort of mapping.  I follow an OSM doctrine of the "the more, 
the merrier" and see nothing wrong with experimenting by adding separate 
polygons of burnt areas. Adding a burn year would throw the question of 
"when does it stop being burnt?"  from the data to the renderer. Of 
course, the counter argument is that it won't show on maps. But I remain 
hopeful that we will see a federation of national level OSM maps 
rendered to suit local tastes and requirements. Just musing.

Mike

On 2021-10-08 04:28, EON4wd wrote:
>
> Another part of the question is how many trees before it can be 
> classified as such?
>
> I have been to the Grampians within the last 12 months and I did not 
> find any scorched area left. All trees had growth.
>
> If I look at the satellite picture from the OSM id editor, large areas 
> look burnt. Look around Lake Wartook. All this area is definitely not 
> burnt now and I think should classify as covered in trees. Other 
> satellite images show this area better.
>
> I would agree that ‘natural’ areas should be separated from ‘boundary’ 
> layers.
>
> *From:*Adam Horan <ahoran at gmail.com>
> *Sent:* Friday, 8 October 2021 12:59 PM
> *To:* EON4wd <info at eon4wd.com.au>
> *Cc:* OpenStreetMap-AU Mailing List <talk-au at openstreetmap.org>
> *Subject:* Re: [talk-au] Mapping tree cover
>
> There is another aspect to your question, which is how to map 
> woods/trees after a fire?
>
> You're right it looks like someone has mapped the wooded areas as a 
> relation with holes for non-wooded areas
>
> https://www.openstreetmap.org/relation/9300964/history 
> <https://www.openstreetmap.org/relation/9300964/history>
>
> Some of the current gaps might be due to recent fires, and I don't 
> know if they should be mapped as something else. Depending on the fire 
> severity then it's possible the woodland will regrow quickly, slowly, 
> or not for a long time. I assume there's some precedent & 
> convention based on the large fires in the east a couple of years back.
>
> Adam
>
> On Fri, 8 Oct 2021 at 11:33, Adam Horan <ahoran at gmail.com 
> <mailto:ahoran at gmail.com>> wrote:
>
>     I think you're asking the same question as Andrew, but you
>     possibly have different viewpoints or opinions on it.
>
>     I see the map as a painting that's becoming more detailed and
>     accurate as time progresses. In the beginning the map was blank,
>     and people added large areas of landcover just to get something
>     down. Mappers took conveniences like marking a national park as
>     all desert or all trees.
>
>     However now that all the basics have been done mappers are adding
>     more detailed, accurate information and using more
>     sophisticated tagging schemes.
>
>     I think it's entirely right that we map what's on the ground. If
>     there's a 20m gap in the trees for a road, or significant fire
>     break, or there's been clearing, then people should map that in
>     detail if they have time and inclination.
>
>     Also the trees tend not to respect administrative boundaries, it's
>     almost like they don't know they're there... Tree cover extends
>     beyond the National Parks in a continuous run, and similarly there
>     are clearings, lakes, meadows, moorlands within the parks.
>
>     However the first step in mapping this detail is to remove the
>     blanket landcover from the admin boundary.
>
>     Adam
>
>     On Fri, 8 Oct 2021 at 09:22, EON4wd <info at eon4wd.com.au
>     <mailto:info at eon4wd.com.au>> wrote:
>
>         Hi,
>
>         Further to Andrew Parkers question about forested areas.
>
>         I am also a casual user for uploading data and I also create
>         my own maps from the data.
>
>         My interest is in 4wd tracks.
>
>         The Grampians has had the ‘landcover – tree’ ‘areas’ changed
>         which in my opinion is now not correct.
>
>         See
>
>         https://www.openstreetmap.org/edit#map=16/-37.1268/142.3867
>         <https://www.openstreetmap.org/edit#map=16/-37.1268/142.3867>
>
>         The Grampians is a National park and is covered in trees.
>
>         There are a number of rocks and rocky outcrops (lots actually)
>         and a few lakes and roads plus some swamp and rock quarries,
>         but generally speaking it is completely covered in trees,
>         everywhere, including the rocky outcrops.
>
>         I suspect that some well meaning person has mapped what they
>         could see via a satellite image after a fire went though.
>
>         Question, How can I identify this person so that I can contact
>         them to be able to find out what they are thinking?
>
>         Traditionally, the whole area is mapped as tree cover and then
>         other features are added on top, such as the lakes and roads.
>
>         Also towards the SA border there are other treed areas that
>         have been very carefully traced out. Yet traditionally the
>         whole area is set with the fence lines and tracks then marked
>         on top.
>
>         Not necessarily wrong, but tracing the exact line of where the
>         trees finish and the road side has been cleared, is not really
>         helpful. Or is it?
>
>         Thanks
>
>         Ian Winter
>
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