Re: Total Station or 3D Laser Scanning?

I hardly say it could be done.
1. Laser sanner could provide such precision by applying VERY strong
filtering algorithms. Granite surfaces (even if glass-like finished) cause a
lot of noise. In any case you'll need to set up in elevated position to
"read" the floor, but I don't know if scanners are capable to work in
upside-down
2. If you are required to survey edges you must notice that scanner projects
a brute force grid, nothing even close to feature following. So you'll need
to process huge point clouds (+bilions) to mathematicaly extract hard-lines
(edges and corners) (Are you that skilled in math-stats-alg-comp-geometry to
design such algorithms?)
Also the price of the hardware could be an obstacle. Consider to rent it.
3. Prismless EDM radiation and conventional traversing would not give
(today) such a high accuracy but under very restrictive conditions. (most
shots wouldn't comply your requirements because of the angle of incidence of
laser beam).
4. I would first of all sugest to design a well suited statistic sample
test. You could guarantee a certain confidence level (lets say 95% or up to
99%) to stablish an inference about the whole area status by analysing some
randomly spaced sample areas (the size of the sample is not a difficult
guess if you ask an expert). This areas could be analysed by methods that
could be reasonably applied to fit that specs: conventional edm tacheometry
with a miniprism uside-down.

Is just an opinion.
Best regards

"Stu" <[EMAIL PROTECTED]> escribió en el mensaje
news:[EMAIL PROTECTED]
> Hi,
>
> My company has recently won a contract to survey as-built positions
> and levels of granite slabs and cobbles in a 60m x 40m indoor area. We
> are required to survey all slab corners and individual cobbles ( a
> total of 28,000 points) to an accuracy of +/- 3mm. The client is
> hoping to make a claim against the flooring contractor for being out
> of spec, trip hazards etc.
> I was originally going to survey it conventionally with total station
> and prism, but I have been thinking about other solutions. Would laser
> scanning be a viable alternative? Would laser scanning give the
> required accuracy? The survey was priced for about 3 weeks field time
> and 1 week office.
>
> Any advice gratefully received.
>
> S. Thomas
> Geomatics Manager