[CANUFNET] High precision (+/- 10cm) tree location

Tue Nov 6 15:46:51 EST 2018

In order to use a rangefinder for offsets, you stand outside of the tree crown, in full view of the satellites and shoot the rangefinder laser under the crown at the stem.  The accelerometer in the device and the laser calculates the offset from the point from where the gps signal was collected and the tree stem is.  I can reliably plot trees to +/- 1 metre using this method.  Indeed this is one of the prime industrial uses this device was designed to do.

GPS is used by surveyors in all industries all over the world and has been for decades now.  I’ve been using GPS and GIS solutions for over 20 years now, and it gets better every year.  

 As regards needing lots of “data mining” or a knowledgeable person, I have taught myself to process collected tree data using a free GIS application, QGIS, which can produce maps with legends, icons, numbers etc, as well as exporting tabular data at no cost.  The “curvature of the earth” is accounted for using regional map projection conventions, any of which can be easily configured using this free, open-source software.  I collect data using Trimble Terraflex, which costs $250 per year, but there are cheaper/free software options out there.

As well as being fairly costly, Arcpad does not support Google Earth, and the method of dropping a pin onto a tree seen on aerial mapping is problematic due to the parallel error inherent in aerial and satellite imagery.  Also the map projection embedded within such imagery can sometimes not be re-projected, causing additional errors.

Scott Fairley MA(landarch) MSc(for) LMLI M.arbor.A
consulting arborist|landscape designer

American Society of Consulting Arborists Member
PNWISA Chapter Member
ISA Certified Arborist UI-1192A
TRAQ Tree Risk Assessor
UK Licentiate Landscape Architect
UK Professional Member of the Arboricultural Association
UK Professional Tree Risk Assessor (PTI) LANTRA Awards

email: scott at treesandlandscape.com
web: www.treesandlandscape.com

> On 6 Nov 2018, at 20:26, Peter Shields <peter.shields1 at hotmail.com> wrote:
> 
> My experiences have told me GPS is not the best solution. A problem with GPS is the actual locations and where property boundaries are near, and cm truly count, it will be off.  You would still need to ensure the GPS is then plotting to account for curvature of the earth etc. Which sounds excessive, but it needed if GPS will be your source for accuracy.  Under a canopy is difficult but I have done this so long as a large and know landmark (I.e. a tree, path, tower, fence, etc.) can be found using the below method.
> I have completed many inventories, but they will require some “building” likely with a very knowledgeable person.  Have an ArcPad build set up to use a “head’s up” point data collection using high resolution orthophoto’s.  But google earth is not bad these days, and usually fairly current.  This will require some data mining pending on where you are collecting.  This will require for you to be able  to capture some reference points and measuring on the ground to find them.  Using ArcPad, you can measure fairly reliably to drop your point.  Hardware required will be a tablet.
> The only need for sub metre accuracy, in my experience, has been for property ownership, and if it is contentious, you will likely need a proper surveyor to assist to confirm.
> Hope this helps. 
>  
> Peter Shields
> ISA Board Certified Master Arborist ON-0570B, TRAQ
> ASCA Registered Consulting Arborist #536
> peter.shields570 at gmail.com <mailto:peter.shields570 at gmail.com>
> www.linkedin.com/in/peter-shields570 <http://www.linkedin.com/in/peter-shields570>
> (705) 500-4860 <tel:(705)%20500-4860>
> <F59FA0C1450A4FE48FADBC738B6715B8[629675].png>
>  
>  
> From: CANUFNET <canufnet-bounces at list.web.net <mailto:canufnet-bounces at list.web.net>> on behalf of Scott Fairley via CANUFNET <canufnet at list.web.net <mailto:canufnet at list.web.net>>
> Sent: Tuesday, November 6, 2018 1:07:16 PM
> To: Canadian Urban Forest Network
> Subject: Re: [CANUFNET] High precision (+/- 10cm) tree location
>  
> 
> 
> The only device I’ve ever used that can get sub metre accuracy under tree canopy is the Trimble Geo 7x, as it has a built in laser rangefinder which can shoot under the tree crown to provide an offset from an accurate GPS reading. I have one and it works great, but the windows mobile 6.5 software is starting to feel very dated.
> 
> There may be other solutions that can provide a laser offset via a rangefinder linked to the GPS unit with Bluetooth, but I haven’t much experience with them. Arcpad can do this, but you’re back to the issue of generally using windows mobile again.
> 
> Best
> 
> Scott
> 
> 
> Scott Fairley MA(landarch) MSc(for) LMLI M.arbor.A
> consulting arborist|landscape designer
> 
> American Society of Consulting Arborists Member
> PNWISA Chapter Member
> ISA Certified Arborist UI-1192A
> TRAQ Tree Risk Assessor
> UK Licentiate Landscape Architect
> UK Professional Member of the Arboricultural Association
> UK Professional Tree Risk Assessor (PTI) LANTRA Awards
> 
> email: scott at treesandlandscape.com <mailto:scott at treesandlandscape.com>
> web: www.treesandlandscape.com <http://www.treesandlandscape.com/>
> Tel: 1-(778)-583-6098 <tel:1-(778)-583-6098>
> <Fairley email certs.png>
> 
>> On 5 Nov 2018, at 18:30, Maurice, Jerome via CANUFNET <canufnet at list.web.net <mailto:canufnet at list.web.net>> wrote:
>> 
>> Hi Canufnet,
>> 
>> I came across a recent discussion about tree geolocation tools used by some urban foresters (see below). Based on practical experience, is anyone able to recommend one or more devices that are highly accurate (+/- 20cm) for tree inventory ? what would be a reasonable target under closed canopy cover (20cm ? 50cm ? 1m ?)
>> 
>> Thanks a lot.
>> 
>> Jérôme Maurice, Ing.f. M.Sc.
>> 
>> 
>> -----Message d'origine-----
>> De : CANUFNET [mailto:canufnet-bounces at list.web.net <mailto:canufnet-bounces at list.web.net>] De la part de Art Maat via CANUFNET
>> Envoyé : 19 janvier 2017 17:35
>> À : Marie-Hélène Sauvé; Canadian Urban Forest Network
>> Objet : Re: [CANUFNET] tree protection
>> 
>> Mobile software is available from Histree for plotting and or surveying tree locations with species, condition, images and other variable attribute data in field. 
>> 
>> As well GPS hardware is available and can connect to Android or iOS devices via Bluetooth resulting in sub meter accuracy point locations.  Additionally using Histree and on board satelite views a user can also visually reference a location by moving the map while the pin is stationary. Much like Uber interface. 
>> 
>> Regards,
>> Art Maat
>> 780-937-4056 <tel:780-937-4056>
>> 
>>> On Jan 19, 2017, at 3:08 PM, Marie-Hélène Sauvé via CANUFNET <canufnet at list.web.net <mailto:canufnet at list.web.net>> wrote:
>>> 
>>> Hi there,
>>> 
>>> Just to adjust something about GPS and urban forestry: there exists many
>>> types of devices that are accurate enough (+/-10cm precision) to make a very
>>> good distinction between two trees located nearby (and even the property -
>>> if it's a public tree or not). Those devices are way more expensive than
>>> those easy-to-use Garmin or other GPS device used traditionally in forestry.
>>> Those high-level precision GPS are used by some consultants in the Greater
>>> Montréal. So YES, it may be used and applied. The user has to know how to
>>> use it properly though; GIS skills are required!
>>> 
>>> Cheers,
>>> 
>>> Marie-Hélène Sauvé
>>> 
>>> 
>>> 
>>> -----Message d'origine-----
>>> De : CANUFNET [mailto:canufnet-bounces at list.web.net <mailto:canufnet-bounces at list.web.net>] De la part de via
>>> CANUFNET
>>> Envoyé : 19 janvier 2017 13:12
>>> À : jd at dunster.ca <mailto:jd at dunster.ca>; Julian Dunster; Michael Richardson; Canadian Urban Forest
>>> Network
>>> Objet : Re: [CANUFNET] tree protection
>>> 
>>> Unfortunately GPS is not accurate enough to plot trees, especially when
>>> landmarks that are accurately located by a surveyor aren't close by (i.e. a
>>> forest or large natural area).  GPS's currently available don't have the
>>> resolution to separate two trees that are 2 feet apart, or may be on the
>>> other side of a property line with 100% accuracy.  A critical point. It's a
>>> help but not the solution, yet.
>>> 
>>> CAD and GIS are great for plotting the data (we use both) but the locations
>>> need to be accurate to start with. The days of drawing-in a dot by hand on a
>>> site plan are gone.
>>> 
>>> Stephen Smith
>>> ISA Certified Arborist, Urban Forester
>>> Urban Forest Associates Inc.
>>> -----Original Message-----
>>> From: Julian Dunster via CANUFNET
>>> Sent: Thursday, January 19, 2017 11:56 AM
>>> To: Michael Richardson ; Canadian Urban Forest Network
>>> Subject: Re: [CANUFNET] tree protection
>>> 
>>> Many of arborists in Britain regularly use GPS, GIS, and CAD routinely for
>>> development projects. One of them developed special CAD software for the
>>> purpose. The lack of its use in Canada almost certainly reflects a lack it
>>> being taught in curricula, as part of professional practice. We still focus
>>> on pruning, planting, fertilising and tree stuff, all of which is fine but
>>> needs expanding to the 21st century to include effective use of technology.
>>> Several of my colleagues in BC use CAD all the time. I use GPS and GIS.
>>> 
>>> We need to expand the horizon of what arboriculture and urban forestry might
>>> / should entail. At the same time we can also inform surveyors and
>>> architects of we expect them to produce - such as CAD symbols for canopy
>>> that are scaled to reality on the ground, not simply rubber stamped on a
>>> plan, all at the same size (a pet peeve).
>>> 
>>> On Behalf of Dunster and Associates Environmental Consultants Ltd.
>>> 
>>> 
>>> Dr. Julian A Dunster R.P.F., R.P.P.., M.C.I.P., ISA Certified Arborist, ASCA
>>> Registered Consulting Arborist # 378, ISA Tree Risk Assessment Qualified BC
>>> Wildlife Danger Tree Assessor Honourary Life Member ISA + PNWISA
>>> 
>>> North American distributor for Rinntech
>>> www.dunster.ca <http://www.dunster.ca/>
>>> 
>>>> 
>>>> Some interesting thoughts here.
>>>> 
>>>> Those little dots; most arborists I know do not have the equipment or 
>>>> expertise to to locate trees with any precision, nor the GIS software 
>>>> to plot them.  If an arborist is using a plan created by a surveyor 
>>>> than surely the arborist must locate and plot not the tree, but the 
>>>> entire trunk diameter or root collar/trunk flare with the same 
>>>> accuracy and precision.

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