I want to record the relative position of several thousand points on a block of land down to about 5cm or 10cm accuracy. What would be the easiest device to do this? Can GPS recievers get this accurate? Are there cheap laser distance meters or something? The max distance between point is about 25m. Any ideas?
Laser unit , several hundred $ but will do it out to 50 M or more in moderate light and further at duck
oops.. dark :)
A 30m steel surveying tape would be a good start. Cheap too.
-- Regards, Adrian Jansen adrianjansen at internode dot on dot net Design Engineer J & K Micro Systems Microcomputer solutions for industrial control Note reply address is invalid, convert address above to machine form.
Darkwing Duck???
no idea what that is
You can't see it unless you are Peking.
Those kinda jokes quack me up.
sounds like a bit of a quakup to me
First, GPS can achieve accuracies down to about 2 mm, if you really need it. You'd need a geodetic-grade receiver and post-processing using carrier-wave data logged over a period of time.
But the first question HAS to be: what are you trying to do? How accurate do you need your final results to be? You can easily make your individual measurements accurate to 1, 5 or 10 cm, but if you then triangulate your several thousand points, the final accuracy is a function of the cumulative errors [usually using least-squares methods]. Do you need 3D points, or just 2D? An ordinary measuring 30-m tape will usually do for 5 cm accuracy, but several thousand points sounds more like a job for a theodolite, where you can get instantaneous readings one after the other, without the hassles of a tape. There are domestic laser- and sound-based hand-held distos, but I doubt they'd go as far as 25 metres. 10 metres, maybe, but not 25. Stanley make one called an Intellimeasure.
Atom You should explain a bit more about the project.
Post this question on the GPS Australia website.
How big is the block? Why do you need that accurracy? relative to what?
If you are laying out a building, the fibreglass 30m tape will probably suffice, provided the block is flat. If this is your farm, then a basic GPS will suffice.
telephone. get the yellow pages, look under "surveyors".
yes. differential GPS can easily
oh, you want cheap, set up some profiles and run a grid of string walk round with a measuring stick.
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