[GRASSLIST:2147] Re: Aerial photos and noxious weeds

[Roy Sanderson]

Hi Rich

I've tried using GRASS with to identify Juncus infestations in semi-natural
vegetation in upland grazing areas in UK with variable levels of success.
These were based on true-colour aerial photos, scanned in on a flatbed
scanner, imported into GRASS and split into RGB components with r.mapcalc
before a supervised classification.  The availability of other wavebands
e.g. nr-IR would improve the classification, and obviously the lower the
over-flight altitude the better.  However, the key factor determining the
relative success is the contrast in spectral signature between your noxious
weeds and the other vegetation.  If the contrast is good then I see no
reason why the technique shouldn't work well.

Roy

At 14:28 23/07/01 -0700, Rich Shepard wrote:
>  Has anyone -- particularly in the U.S. -- used GRASS on scanned aerial
>photos to identify noxious weeds? I wonder if this is a practical approach,
>once one ground-truths the various species and trains the software.
>
>Thanks,
>
>Rich
>
>Dr. Richard B. Shepard, President
>
>                       Applied Ecosystem Services, Inc. (TM)
>            2404 SW 22nd Street | Troutdale, OR 97060-1247 | U.S.A.
> + 1 503-667-4517 (voice) | + 1 503-667-8863 (fax) | rshepard at appl-ecosys.com
>                 Making environmentally-responsible mining happen.
>
>
>

----------------------------------------------------------------------------
Roy Sanderson
Centre for Life Sciences Modelling
Porter Building
University of Newcastle
Newcastle upon Tyne
NE1 7RU
United Kingdom

Tel: +44 191 222 7789
Fax: +44 191 222 6563
r.a.sanderson at newcastle.ac.uk
http://www.ncl.ac.uk/clsm

----------------------------------------------------------------------------