sounds perfect -- but what's the copyright -- technically the entire survey would be a derivitive work.
JR On 22 June 2010 22:14, Barnett, Phillip <[email protected]> wrote: > Surely you need trig points? > http://www.trigpointinguk.com/info/trigpoints.php > > They’ll only get you accuracy to a few centimetres though, not millimetres. > > > > > ** > *PHILLIP BARNETT > **SERVER MANAGER > * > 200 GRAY'S INN ROAD > LONDON > WC1X 8XZ > UNITED KINGDOM > T +44 (0)20 7430 4474 > F > E [email protected] > WWW.ITN.CO.UK > P Please consider the environment. Do you really need to print this > email? > ------------------------------ > > *From:* [email protected] [mailto: > [email protected]] *On Behalf Of *John Robert Peterson > *Sent:* 22 June 2010 21:33 > *To:* talk-gb OSM List (E-mail) > *Subject:* [Talk-GB] Reference points for total station > > > > I have managed to gain access to a total station ( > http://en.wikipedia.org/wiki/Total_station) for doing a survey of a built > up university campus. The goals of the project are 2 fold: > > 1) learn some new skills > 2) get some decent data for OSM of the area. > > Now for anyone that doesn't know about these things, they measure angles > horizontally with a very precise optical system, and use an IR range finder > beam to locate a reflector prism to within millimeters. It's range is into > the hundreds of meters. It has a sophisticated processing unit in it that > can do some helpful maths and data storage for you. The prism is on top of a > stick of measured length, with a spirit level built in, and is carried and > placed by an assistant known as a "stick monkey". > > It's well known to that that actually know what they are talking about in > these circles, that positioning the stick is actually the talented part of > the operation and that repeatedly pressing the green button on the box is > actually less intellectually demanding. > > There is also a "reflectorless" version that I may be able to gain access > to later, but that's not guaranteed. This uses lasers, and requires no > "stick monkey" and associated gibbons. The plan is to use this for heights > of buildings only. > > The device provides accurate 3d positions with the following caveat: it has > no idea where it is, or where it's pointing until it gets reference data, > this can be done in the following ways: > > It knows where down is via gravity; > > If you give it a number of calibrated reference points, it can work out > where it is and where it's pointing, error control is built into this, so it > needs at least 3, preferably 5 points, one of the points needs to have > proper altitude; > > If you once get it calibrated, you can generate more calibrated reference > points, meaning that you can daisy chain it off itsself; > > Since this is a learning process into surveying, we want to actually do it > to an accuracy of a few millimeters. > > So the question is -- where do we get the first points from? There is one > very old and well known building right in the middle of the area, and there > are a number of land marks around, these may be usable, but how do I know > their positions? > > There are also a number of distant landmarks in the area, but most would be > too far away to use effectively, I dont' think the machine has the ability > to take points only as distant points with no distance, though I do have > access to the raw data, and would happily do the maths myself. > > Thanks, > JR > > > > Please Note: > > Any views or opinions are solely those of the author and do not necessarily > represent those of Independent Television News Limited unless specifically > stated. This email and any files attached are confidential and intended > solely for the use of the individual or entity to which they are addressed. > If you have received this email in error, please notify > [email protected] > > Please note that to ensure regulatory compliance and for the protection of > our clients and business, we may monitor and read messages sent to and from > our systems. > > Thank You. >
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