HELP!

[stonecirclegirl]

Hi all. Hows everyone? Haven't been on here for a while due to exams etc etc but I'm back with another annoying question (sorry!)

I am trying to put together a field workbook for end of first year to be used in the field on our dig during the summer. Two of the subjects we have to put in are triangulation and trilateration. Now I know I should probably know what these are by now but we seem to have had two conflicting lectures on what they are and what they are in relation to :face-huh:. All that is clear is that they are in relation to grids and plotting (probably)

Can anyone out there, in your infinite wisdom, please explain??

(Got out some library books and they seem to say different things too - I'm totally confused! Thought someone out there might be able to explain to me in idiot proof language...[?]

Thanks
:D

[Cautionary Tale]

I can provide you wth a very long winded explanation (and am happy to do so), but first off try looking at wikipedia - it has some very clear diagrams which explain the two really very clearly. Essentially trianulation is about angles, while trilateration (which I tended to use more often) is about having a known baseline and measuring distances.

Of the Clan Sutton

[kevin wooldridge]

quote:Originally posted by Barnesy
trilateration (which I tended to use more often) is about having a known baseline and measuring distances.

Sorry to be awfully pedantic, but your explanation as it stands is really describing offsetting rather than trilateration.

Trilateration is where 'distance' measurement (as opposed to 'angle' measurement) of a target point is taken from three or more known stations, not necessarilly a known baseline. The polar co-ordinates of the target point can then be established by using a beam compass to draw overlapping circles from each station, using the relevant measured distance as the radius, or by using the complicated mathematical formula as described in Wikipedia.

After doing the maths you may feel that triangulation and the use of the sine rule is an easier way to establish polar co-ordinates of any given point.

In the field I recommend a Total Station, as it is unlikely that at any future point in your archaeological career, (unless of course its as a lecturer at a field school for undergraduates) will you expected to use either triangulation or trilateration, although Pythagoras might occassionally come in handy.

[stonecirclegirl]

Thanks all for you advice.

I'm beginning to get trilateration now, but triangulation still confuses me. In one of our lectures triangulation was described as measuring from two known points (ie ends of baseline) to object, and nothing about angles was mentioned. Think thats why I've got myself so fuddled! :face-huh:

Ah well. From now on trilateration is distance and triangulation is angles no matter what! Somewhere along the line I think we've been told the wrong thing - no wonder I've got myself in a state about it!

Thankyou for your help! :D

[Cautionary Tale]

quote:Originally posted by kevin wooldridge
Sorry to be awfully pedantic, but your explanation as it stands is really describing offsetting rather than trilateration.


Bang to rights. Slapped wrists all round. [:I]

I'd still recommend to all those fresh faced site archaeologists out there to have these mathmatical tools at their disposal if they end up doing a minor watching brief which doesn't warrant a total station, though as the price drops I would imagine this will increasingly become less of a concern. May put this to a poll....

Of the Clan Sutton

[Curator Kid]

I agree Barnsey. It's good to know the maths - especially if the electronic gizmos get water in them or their batteries run out. Besides, I doubt the price of a total station will ever drop lower than that of a couple of measuring tapes.

[BAJR Host]

Exactly... I always try to teach people the basics of survey with a theodolite first... then a gizmo.... if you don't get the maths, you can't understand what you are doing... if you understand the background principals, you can actually 'force' your Total Station' to do things - (no nothing saucy!) by understanding the geometry and maths behind what you are doing.



Another day another WSI…

[Magpie]

I would say that you should master the basics using tape measures and Pythagoras and at some stage in your archaeology career you will have to manage without a total station or theodolite. As well as the price advantage of a couple of 30m tapes over a total station they are a lot easier to carry on that 5 km treck into the uplands when you work in remote areas :D

[stonecirclegirl]

Thank you all:D

I'm sure you'll be pleased and somewhat relieved to know I got my mark back for the workbook, and I got 80percent! Yay.

So, no more questions... until I come up with another dilemma anyway...[:I]

[BAJR Host]

:D:D Wooooooooooo Hoooooooooooooo

good job

Another day another WSI?

[stonecirclegirl]

Thanks! :D

[AchingTrenchHeadAtADesk]

This place is soooo helpful. Can anyone give me a fiver?

[garybrun]

I can give you a fiver... but it will cost you a tenner. :-)

http://www.ukdfd.co.uk
Recording OUR heritage for future generations.