LTE: Letters to the Editor
Professional Surveyor Magazine - February 2014
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Leading the Pack
I read Gavin’s article about Leica [July 2013] with great interest; the MS50 is what I am planning on buying shortly.
PSM was great, as usual. You guys are leading the pack with content and quality.
William T. Derry, PLS
More Practice, Less Theory
As a practicing surveyor I recognize the importance of theory. But I’m afraid the NGS has made it pretty difficult to follow their revisions. What I would find most helpful is a simple x, y and z chart that shows the change in feet or meters for the location of a point relative to the various reference frames over time. Is the 1986 realization .003 m different in x or 0.3 meters than that in 2007 for our area? A chart with these values for each corner and in the center of our state, New Mexico, would indicate the change in a meaningful manner.
Keep writing your articles.
Gallup, New Mexico
I don’t entirely disagree with you. I am not sure that the National Geodetic Survey realizes the problems the datum changes are creating in the industry. Lately, I have been asking the NGS to put the dates of these coordinate changes on their website. If surveyors have access to the dates of the changes in realizations to NAD83, they will know when they go to the field that they need to localize to the results of a previous survey. Quite honestly, as owners of the coordinate systems, they should maintain a file of these changes including, as you suggest, the affects on the coordinates.
When they created the HARN, they let everyone know the magnitude of this change, but this was on a national level. I heard that the magnitude of change for NAD83 (2011) is small when compared to NAD83 (2007), somewhere at the cm-level. This may be true for some places in the United States, and may even be true for most of the United States, but this is not what I personally saw nor what the surveyor I referenced in the article saw.
Additionally, it would be nice if they maintained transformation parameters between the different realizations of NAD83. While I understand that they may not have enough reliable data for the early realizations like the HARN and early CORS versions, they did have transformation parameters for NAD83 (2007) to WGS84 (G1150), which is no longer available on their website. Nor is there a transformation going from NAD83 (2007) to NAD83 (2011) even though both are based on ITRF datums, which have transformation parameters between all its different datums.
All I can say now is if you are aware of changes to WGS84 or NAD83, then surveys using previous realizations will need to be localized to place your survey in the older realization. Mathematically, you could go the other way, but this may require some programming on your part, since software supplied in controllers and adjustment packages usually goes to the local system, which in this case would be the previous realization, and not the other way.
Impossible Not to See
Enjoyed your article about the Mt. McKinley climb
in the December issue of Prof Surv.
Wish you had a current picture of the monument from the climb! “Impossible not to see.” Well, take a photo, then! And those guys should have at least put a hand held on the mon. for a few minutes so you could have showed us a lat and long of its position.
Maybe next time.
Paul G. Landau, PLS
Hood River, Oregon
Hi Paul, thanks for reading and writing in.
The genesis of that story was very much a coincidence. The two brothers who did the climb were not looking for the monument; they happened to see the monument while they were up there and mentioned it to their grandfather. He’s the one who mentioned it to Rhonda Rushing’s father because they live in the same retirement community.
Had we sent the climbers on the mountain ourselves to look for the monument, we definitely would have asked them to take a picture or two and some measurements.
UPDATE: The “Pre” in Precision
A revised version
of this article detailing a visit to Leica Geosystems in Switzerland is on our website.
The paper [that the January feature article
was based on] was, in my opinion presented out of context when framed with the 2012 archaeological mission lead and executed exclusively by Parks Canada.
The paper describes a multi-year, multi-departmental, multi-disciplinary project known as the Arctic Charting and Mapping Pilot Project. It was written from a surveyor’s perspective to which Parks Canada’s search for evidence from the Franklin Expedition was but one of many interests.
While Parks Canada influenced the selection of the project area, the overall execution of this project (from planning, mobilization to demobilization) was led by the Canadian Hydrographic Service in collaboration with other federal government departments, sectors and private interests. My dear colleagues at Parks Canada were partners in the collaboration, with relatively less skin in the game compared to the equipment assets and resources my department was bringing to the table. The research vessel, Martin Bergmann, was a lame duck of a ship, which proved to be more trouble than she was worth.
Because of the sensationalism of media coverage associated with the “Search for Franklin,” the true story of the project was never recorded. The Canadian Broadcasting Corporation (CBC) did (post media frenzy) do the project some justice by airing a series of scientific, surveying and mapping stories for the French Language (Radio Canada) version of Discovery Channel, Decouvert. To date, no English-language media has framed the project in this regard.
My disappointment in what was published in Professional Surveyor is rooted in my expectation that a surveying publication would actually frame the story as my paper intended, from a surveyor’s perspective. Clearly had I seen a proof copy prior to publication, I would have withdrawn permission for you to use my work within the context your magazine chose to frame it.
Canadian Hydrographic Service
We regret difficulties in our editorial process that resulted in miscommunication with Andrew and thus an article that did not fully represent his white paper.
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