Most large wildfires do not burn the canopy (the tallest trees) in forests
with trees over 10 meters in height.

The perimeter of the wildfire, shown commonly on public maps, does not
determine which areas have been burned. Often there are large areas of
vegetation along canyon bottoms and streambeds which are unburned, within
the perimeter.

You will need new aerial imagery or detailed on-the-ground survey to
determine the surviving areas of vegetation.

I would not recommend attempting to map the current official perimeter of
the fire, since this changes on a daily or hourly basis: it is a temporary
event which is not really verifiable from the standpoint of an
OpenStreetMap volunteer mapper.

Database users who need these perimeters should download the latest version
from the official sources.

- Joseph Eisenberg

On Thu, Sep 24, 2020 at 2:32 PM stevea <> wrote:

> I didn't get a single reply on this (see below), which I find surprising,
> especially as there are currently even larger fires that are more
> widespread all across the Western United States.
> I now ask if there are additional, appropriate polygons with tags I'm not
> familiar with regarding landcover that might be added to the map (as
> "landuse=forest" might be strictly true now only in a 'zoning' sense, as
> many of the actual trees that MAKE these forests have sadly burned down, or
> substantially so).
> Considering that there are literally millions and millions of acres of
> (newly) burned areas (forest, scrub, grassland, residential, commercial,
> industrial, public, private...), I'm surprised that OSM doesn't have some
> well-pondered and actual tags that reflect this situation.  My initial
> tagging of this (simply tagged, but enormous) polygon as "fire=perimeter"
> was coined on my part, but as I search wiki, taginfo and Overpass Turbo
> queries for similar data in the map, I come up empty.
> First, do others think it is important that we map these?  I say yes, as
> this fire has absolutely enormous impact to what we do and might map here,
> both present and future.  The aftermath of this fire (>85,000 acres this
> fire alone) will last for decades, and for OSM to not reflect this in the
> map (somehow, better bolstered than a simple, though huge, polygon tagged
> with fire=perimeter, start_date and end_date) seems OSM "cartographically
> misses something."  I know that HOT mappers map the "present- and
> aftermath-" of humanitarian disasters, I've HOT-participated myself.  So,
> considering the thousands of structures that burned (most of them homes),
> tens of thousands of acres which are burn-scarred and distinctly different
> than their landcover, millions of trees (yes, really) and even landuse is
> now currently tagged, I look for guidance — beyond the simple tag of
> fire=perimeter on a large polygon.
> Second, if we do choose to "better" map these incidents and results (they
> are life- and planet-altering on a grand scale) how might we choose to do
> that?  Do we have landcover tags which could replace landuse=forest or
> natural=wood with something like natural=fire_scarred?  (I'm making that
> up, but it or something like it could work).  How and when might we replace
> these with something less severe?  On the other hand, if it isn't
> appropriate that we map any of this, please say so.
> Thank you, especially any guidance offered from HOT contributors who have
> worked on post-fire humanitarian disasters,
> SteveA
> California (who has returned home after evacuation, relatively safe now
> that this fire is 100% contained)
> On Aug 29, 2020, at 7:20 PM, stevea <> wrote:
> > Not sure if crossposting to talk-us is correct, but it is a "home list"
> for me.
> >
> > I've created a large fire perimeter in OSM from public sources,
> .  This is a huge fire (sadly, there are
> larger ones right now, too), over 130 square miles, and caused the
> evacuation of every third person in my county (yes).  There are hundreds,
> perhaps thousands of structures, mostly residential homes, which have
> burned down and the event has "completely changed" giant redwoods in and
> the character of California's oldest state park (Big Basin).
> >
> > This perimeter significantly affects landuse, landcover and human
> patterns of movement and activity in this part of the world for a
> significant time to come.  It is a "major disaster."  I'm curious how HOT
> teams might delineate such a thing (and I've participated in a HOT fire
> team, mapping barns, water sources for helicopter dips and other human
> structures during a large fire near me), I've simply made a polygon tagged
> fire=perimeter, a name=* tag and a start_date.  I don't expect rendering,
> it's meant to be an "up to right about here" (inside the polygon is/was a
> burning fire, outside was no fire).  I wouldn't say it is more accurate
> than 20 to 50 meters on any edge, an "across a wide street" distance to be
> "off" is OK with me, considering this fire's size, but if a slight skew
> jiggles the whole thing into place better, feel free to nudge.  It's the
> tagging I'm interested in getting right, and perhaps wondering if or even
> that people enter gigantic fires that will significantly change landscape
> for some time into OSM, as I have done.  This will affect my local mapping,
> as a great much has burned.  Even after starting almost two weeks ago, as
> of 20 minutes ago this fire is 33% contained, with good, steady progress.
> These men and women are heroes.
> >
> > To me, this is a significant polygon in my local mapping:  it is a "huge
> thing" that is a major feature on a map, especially right now.  I firmly
> believe it belongs in OSM for many reasons and want it tagged "correctly."
> Yes, there are other maps that show this, I believe OSM should have these
> data, too, as this perimeter will affect much (in the real world) and much
> newer, updated mapping in OSM going forward.
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