Posted By John Francis on 4/5/2009 at 8:07 AM
Well . . . after 2+ years of using the RTK GPS, I've concluded that the initial use of GPS (Static) from conventional surveying, was a much more profound occurrence (production-wise) than to going from static to RTK.
Don't get me wrong, but RTK(at least in the tree-bound midwest), is not so GREAT. It might be "great", but it's not "GREAT!". ADD to this, and in this area of the USA(and probably others), EVERYONE PLANTS PINE TREES ON PROPERTY LINES AND AT PROPERTY CORNERS. A lot of my jobs have actually involved large parcels with NO NATIVE TREES . . . only planted(and often now-huge), PINE trees which are the absolute bane of GPS.
Even with Glonas and sometimes 18+ sats, the time consumed for getting data(away from pine trees and "heavy foliage) ends up comparative to STATIC GPS(somewhere nearby) and conventional operation with a nice reflectorless total station.
I don't do a lot of topographic work in open field and buildings are ALWAYS located using my reflectorless 2005 with the aid of small 1/2" square pieces of reflectorless tape set 4.00' or 6.00' feet above grade.
Often, I find it easier to actually populate a field with about 50 2' long rods with a mark that allows me to bury them to 2" depth(enough to hold them vertical, then to move them to another area and repeat(it's not much more time consuming than the RTK).
The one thing I absolutely love about RTK, is that I "know" that I can rely(or can't rely) on a reading before I leave a site. Albeit, sometimes that reliance is based on multiple shots, measured between and checked and otherwise taking upward to an hour to feel confident with the location. As often as not, these more challenging locations result in conventional traverse anyway.
SETTING pins can be a real pain with RTK in anything but the most open sites, but when in pretty open sites, IT . . . IS . . . NICE.
OVERALL, RTK-GPS has been somewhat of a letdown, in that the places where I "really", want to GPS/RTK-GPS are also places where I really don't want to traverse to conventionally.
If I were to make a now, more-informed decision on equipment and had to choose, the choice would be for one L1/L2 GPS(for OPUS), with a compliment of L1 GPS units and a good reflectorless and additional a lightweight Robotic Total Station.
It's not the problem with RTK . . . it's the problem with the environment . . .
RTK GPS . . . my take
April 8, 2009