Good Morning Everyone,
Thanks for the feedback on my question about mapping cut blocks in
wooded areas. I do appreciate it and understand the points that are
being made by Daniel, Bryan and Bernie. I've thought a lot about this,
however, and would like to address some of the points as it touches a
bit on the varied philosophies we all bring to the project.
The arguments against mapping the cut blocks as openings in the wood
cover seem to fall along the following lines:... and I hope I am not
over simplifying or expanding too much:
1) Change is the nature of the beast. When we map "wood" (or more
accurately, "forest" in OSM terms) it is implied that there will be
logging operations taking place within, with the result that the degree
of cover is constantly changing as is the maturity of the trees. To try
to keep up is fruitless. When one sees a wooded area on a map one
should probably just assume that it will be highly variable.
2) There are people who are maintaining this information to a much
greater level of detail and accuracy than OSM could ever hope to do.
3) To map them is counterproductive.
I have to say that I am not entirely convinced by these well-pointed
arguments.
1) Yes, change is what goes on in wooded areas. That's WHY we map them.
The value of mapping is often in what we learn by comparing maps from
one time period to another. It's important to map so that we can track
that change. Any map is simply a snapshot of what exists at a moment in
time and the maps themselves are outdated the moment they are made as
they are commonly based on outdated data. To use the argument that we
shouldn't map a feature simply because it will be out-of-date tomorrow,
or next week, or next year I just don't think is convincing. The
neighborhood in which I live in Kamloops has changed significantly even
in the last two or three years. Houses, businesses and new streets have
appeared, trails have disappeared, streams have been diverted. It's a
struggle to keep maps up-to-date. But it doesn't mean that it is
pointless to map the features as best we can, with the most currently
available data we have available to us.
2) The fact that better data exist elsewhere is great. Better data
lead to better forest management practices and greater sustainability.
But those data are likely unavailable to us or would need to be heavily
culled for those relevant to OSM. The City of Kamloops has incredibly
detailed maps of the city freely available online. There are overlays
for every curb, parking meter and telephone pole. Does that mean that
we don't map the city in lesser detail?
3) Would it be counterproductive to map cut-blocks? Well, not
counterproductive, but maybe "differently" productive. I think one of
the beauties of this project is that we map things that are not just
important to ourselves, but maybe also to someone else. I get a real
hoot out of just browsing through the list of official map features -
things like... power=cable_distribution_cabinet, amenity=baby_hatch
(where one can anonymously drop off a baby for adoption) and
barrier=stile vs. turnstile. These must be important and useful to
someone. ??? So are cut blocks useful to anyone who might use an OSM
map or load OSM data into their GPS? Hard to say. Maybe to an amateur
birding group or a geocaching club or to someone who is hurt and is
looking for the nearest clearing for evacuation. Don't know. Don't
presume to know.
So am I going to start mapping all the cut blocks? Following my
arguments I probably should... but I probably won't. I will go back and
clean up the gross errors and inconsistencies I find in the CanVec data
as it relates to natural=wood, some of which are offsets along tile
boundaries and inconsistent mapping of cuts along power lines and
pipelines. That will probably be enough as it involves breaking and
rebuilding relations which just make me scream. But I'll try to clean
up what we have first.
Anyway, I hope this doesn't sound like a rant because it really isn't.
While I lean towards mapping them, the arguments against are well made.
We don't maps waves on the ocean... we accept that it will be variable.
Maybe natural=wood is similar? Dunno. That's why I asked for guidance.
Truly, thanks for your responses.
Sam L.
-----Original Message-----
From: Connors, Bernie (SNB) <bernie.conn...@snb.ca>
To: 'Bryan Crosby' <azubr...@gmail.com>, 'talk-ca'
<talk-ca@openstreetmap.org>
Subject: Re: [Talk-ca] Mapping cut blocks in "wooded" areas
Date: Mon, 07 Mar 2011 09:28:45 -0400
Bryan,
I would have to agree with your argument. I have some
knowledge of the forestry GIS that is used here in NB and it would be a
daunting task to include cut blocks in the forest. There is more than
enough OSM work in Canada just getting the road network built it would
be counterproductive to spend a lot of time on forest cut blocks.
Bernie.
--
Bernie Connors, P.Eng
Service New Brunswick
(506) 444-2077
45°56'25.21"N, 66°38'53.65"W
www.snb.ca/geonb/
From: Bryan Crosby [mailto:azubr...@gmail.com]
Sent: Saturday, 2011-03-05 01:58
To: 'talk-ca'
Subject: Re: [Talk-ca] Mapping cut blocks in "wooded" areas
I would tag it as natural=wood as I don’t feel that there is any
distinction between a 2-year old stand and a 250 year old stand in terms
of being wood, or forest. They are merely different ages. Licensees
maintain incredibly accurate and up-to-date maps that indicate the
different openings and their respective stages of development. They
have dedicated GIS guys that maintain these maps as fast as techies
bring it in. I suppose, in theory, an OSM tag could be used to indicate
the stage of opening development, but one would require the date of
harvesting, the date of planting and the dates of the silviculture
surveys to accurately assess the phase. Unless you are a forester you
won’t have access to that information and would be guessing. I just
feel that attempting to seriously map out such temporary features
accurately goes way beyond the ability of OSM (at this point, at least).
Bryan
From: Samuel Longiaru [mailto:longi...@shaw.ca]
Sent: March-04-11 9:43 PM
To: talk-ca
Subject: Re: [Talk-ca] Mapping cut blocks in "wooded" areas
I very much see your point which is why I was asking for some direction.
I guess it comes down to whether the map should reflect what we see at
some given snapshot in time, or whether it is reflecting the overall
landuse scheme. In short, while standing in the middle of a clear-cut,
would it be more accurate that my map show that spot as wooded or not
wooded?
Sam L.
-----Original Message-----
From: Bryan Crosby <azubr...@gmail.com>
To: 'talk-ca' <talk-ca@openstreetmap.org>
Subject: Re: [Talk-ca] Mapping cut blocks in "wooded" areas
Date: Fri, 04 Mar 2011 21:11:20 -0800
RE: cut-blocks
As someone who has spent done time as a forest technician, I strongly
advise against mapping forestry activity. Cut block spatial data
changes daily and any images used to trace are out of date. There are
literally tens of thousands of clear cuts in British Columbia alone and
there is absolutely no way OSM mappers would be able to keep up with
changes. Keep in mind that most clearcuts on crown land (and in some
cases, private land) are temporary openings in various stages forest
development. A 2 year old stand is just as much a forest as a 25 year
old free-to-grow stand or a 250 year old stand of timber. I believe
that mapping a privately held ‘Christmas’ tree farm would be pertinent,
but these are radically different from commercial forestry openings.
I would also advise extreme caution in using images to map forest
development roads unless are working on a high traffic mainline. Many
spur roads are in various stages of deactivation. It may look like a
road from the outdated image, but it may have been completely
deactivated and replanted. A site inspection is the only way to be
sure.
Bryan
British Columbia
From: Daniel Begin [mailto:jfd...@hotmail.com]
Sent: March-04-11 8:19 PM
To: 'Samuel Longiaru'; 'talk-ca'
Subject: Re: [Talk-ca] Mapping cut blocks in "wooded" areas
Hi Samuel,
About tagging forested areas, I would use landuse=forest only if it is
obvious on the field that the area is managed/harvested, as for
landuse=orchard or landuse=vineyard. We have a lot of Christmas tree
plantations in the area and I map them as landuse=forest because it is
obvious on the imagery and on the field.
If it is difficult to determine if an area is under timber lease or not,
because it looks the same, I would keep it natural=wood...
About Cut blocks, I would map the hole they create that wooded area. If
the area is replanted, then some OSM contributor will remove the hole
you map in 10-20 years from now!
Mapping the reality is the best we can do and because the reality
changes over time, we can keep mapping !-)
Daniel
________________________________________________________________________
From: Samuel Longiaru [mailto:longi...@shaw.ca]
Sent: March-04-11 21:45
To: talk-ca
Subject: [Talk-ca] Mapping cut blocks in "wooded" areas
Hi Everybody,
I've been importing CanVec mostly south of Kamloops for the past several
weeks and am going to take some time now to go back and bring stuff up
to date. One question I have though is in regards to how to treat cut
blocks in the wooded areas.
I see according to the map features wiki, that the CanVec imported tag
of natural=wood is technically not correct, at least for here, as wood
is to be reserved only for completely reserved/unmanaged areas. I guess
most of what I have should really be mapped as landuse=forest but I have
not made the change because what is under timber lease and what is not
would be difficult to determine. In one sense it's all managed to some
degree or other. But my point is rather what should be done with the
cut blocks, which in some areas constitute up to 50% or more of the
forested area. http://osm.org/go/WJ1cj_R is a typical area. It seems
improper to keep them as wooded when they are clearly not, and yet most
are replanted and will be wooded again someday... or at least that's
what they keep telling us.
I started mapping them as it truly gives a more accurate representation
of the current state of affairs on the ground... but thought I'd better
get some guidance before proceeding too far.
Thanks,
Sam L.
Kamloops
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