[GRASS5] datum support in GRASS

[Rich Shepard]

On Mon, 17 Jul 2000, Michel Wurtz - ENGEES/CEREG wrote:

> Hmmm... I'm working with agriculture involved people, and for precision
> farming : they want a precision up to 10 cm or less.

  I don't want to go too far off topic, but I must respond to this. Over the
years I have seen demands for accuracies much greater than are really
needed. Governments (and regulators) are particularly guilty of this. I have
come to believe that this demand comes from ignorance of the real world and
what is required for the desired results.

  Even in precision agriculture apps, 10 cm is absurd. I would like the
opportunity to have one of these folks walk a field with me, taking soil
and/or plant samples at 10 cm intervals and show me that there are
significant chemical (or growth) differences at that spatial resolution.

  I went through a long negotiation with wetland regulators in Oregon and
Washington a number of years ago. They did not want to accept our 5-m
accuracy GPS delineation of wetland boundaries; they wanted surveyors to 
locate with 2 cm accuracy the boundary flags we placed. Finally, I took them
to a wetland we delineated and asked them to place boundary flags, too. They
finally realized that the boundary is a transition zone, and flag placement
is a matter of judgement. So, they don't have to be mapped with such high
precision.

  Even in today's world of high-tech agriculture, I doubt that a piece of
farm machinery can affect the soils or crops at 10 cm resolution. And, even
if it could, that it would make any difference in crop yield and profit.

  Bah, humbug! :-)

Rich

Dr. Richard B. Shepard, President

                       Applied Ecosystem Services, Inc. (TM)
              Making environmentally-responsible mining happen. (SM)         
                       --------------------------------
            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


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