If you are thinking about a GPS that you can use to do topo plans for landscape design, you need to spend about $20k to get anything with that kind of accuracy (GPS survey equipment).
If you're looking for something under a grand that's worth using, I think we're still years away. The manufacturers are still calling the $10K systems "low-cost" and "entry-level."
Bling or no bling, I work in an office that has a $20k plus GPS instrument less than a year old and not the lowest priced survey quality unit. It needs more than just satelites to "correct" it. It needs on the ground stations that are bought and paid for by bigger companies that have invested in it for their own benefit (but everyone else gets the benefit as well). Our working area is between two that are about 30 miles apart. It still is difficult to get a good in a lot of places with all of that. It is not uncommon to be in a place where the +/- is more than a foot vertical and horizontal.
I don't know what kind of answer you are looking for, but that is how it is.
So in all seriousness, how does that work- do you shoot a few grades the old-fashioned way, and then compare the results to what the GPS gives you? I would have to think that when it gets that far out of whack, you're back to grade lasers and what have you?
To the OP- I gotta be honest, I shot a property yesterday that drops 16' in elevation from one end to the other, using my $500 laser transit from Home Depot. In less than an hour I located windows, doors, deck, driveway, existing trees, shot grades all across the back on a grid, and photographed the site; it'll take me another hour or less to draw the basemap. I love the gee whiz toys as much as the next guy, but given that the awesome stand-alone systems (Bartlett uses the Ghostbuster-backpack looking setup that starts at $50K per unit) are so expensive, and the cheap ones have a margin of error worse than +/- three feet, I just don't think you're going to find the better mousetrap just yet. Maybe in five years, but not now.
Of course, if you DO find it- by all means, sign me up!
So in all seriousness, how does that work- do you shoot a few grades the old-fashioned way, and then compare the results to what the GPS gives you? I would have to think that when it gets that far out of whack, you're back to grade lasers and what have you?
No, it lets you know its margin of error as you are working with it. It tells you how many satelites you are hooked up with and the accuracy. Most of the time it locks on and it is very accurate, but not everywhere. Tree cover gives you problems, too. If you are in a place where it is not getting the right level of accuracy, you just don't use it.
The good thing is that it is in the same coordinate system as most if the GIS in my area and the vertical datum is NGVD 88 so you don't need to adjust the datum or rotate points if you use that system. Our office uses it to set up the survey crews on bigger jobs and especially to confim benchmarks in flood zones.
No one can be sure that they are giving you good advice if you don't say what youwant to use it for. All of these things are good for some uses. It just depends what you need it for. Since your profile says that you do landscape design it makes me assume that you want to use it for getting data for base plans for designing landscapes.
Both Papercutter and I also measure up properties for landscape plans. I don't use a GPS or survey equipment in my landscape design office at home (I have a day job in an engineers office, you probably have more equipment and do more landscape plans than I do, so can relax about thinking I'm talking down to you), but I am always looking into the easiest and fastest way to do base plans just like you.
I happen to work with guys that are very familiar with what is available and what it costs. Sometimes I go out in the field with them so I know a little bit.
The manuals for both the Garmin GPSMAP 76Cx Handheld GPS Unit and Garmin Oregon 550t GPS Navigation say the accuracy of the altimeter is "+/- 10' " and 10'-16' for GPS. It is basically good for hiikkng, if that is good enough for you, you'd be all set.
The Topcon is a survey quality GPS that says it is good to centermeter IF you have some accessory components that work with one of those augmentation stations I mentioned above. That would be great for landscape base maps or layout for that matter. It ain't cheap though.
OK buddy
True points to your view of the way business is done on your side of the fence(truly good work).
My point (as you put it together) is to get into an area to be designed and collect the basic layout (accurately, cost efficiently and timely-as a client would want).
The problem is the method:
Using a string level and an almost 10 year old Brunton Multi-Navigator MNS GPS ( that had has an accuracy of + or - 1' ( again 10 years ago).
Ok - lets put it this way:
In 9 years, your saying advancements in GPS or land surveying is still dealing in "Feet" for accuracy, on a hand held?
Well I guess I don't feel as poor as I thought. Even Papercutter's system is still very normal and under a grand in cost.
I just thought there was something a little better out there by now, mind you, Im not trying to take away what a real surveying team does at major sites like yours. My job is mostly backyards (as you guessed).
I'm om both sides of the fence. I do 1/4 acre landscapes as well as working in a land planning office that does bigger sites.
I'm surprised to hear that you have a device that has +/_ a foot based on what everyone else has been telling me. That is pretty good for a lot of landscape plans. I'd be interested in something like that myself. The spec's on that say 10 meters and one alleged surveyor who reviewed it was impressed that he was within 10'.
The problem is the method:
Using a string level and an almost 10 year old Brunton Multi-Navigator MNS GPS ( that had has an accuracy of + or - 1' ( again 10 years ago).
Ok - lets put it this way:
In 9 years, your saying advancements in GPS or land surveying is still dealing in "Feet" for accuracy, on a hand held?
Well I guess I don't feel as poor as I thought. Even Papercutter's system is still very normal and under a grand in cost.
I just thought there was something a little better out there by now, mind you, Im not trying to take away what a real surveying team does at major sites like yours. My job is mostly backyards (as you guessed).
GPS for the amateur user is only accurate to submeter quality.
There is no way your unit is good down to one foot in elevation. Not today not tomorrow, not ever....This technology is not available to the general public for national security reasons. Only the military has the ability to that kind of technology... GPS is ok for cars and handhelds but only for very rough use...
All handheld units are only good for 10 feet +/- vertical and about six feet horizontal...... I am a Land Surveyor and use a New Trimble Unit. It uses US and Russian Satelites for up to 20 satelites to lock onto at one time. It costs about 50k and then the software to use it is near 15k. This unit uses a cell phone and separate static receiver to work with any accuracy below 1 foot in elevation. Even with this equipment you have to post process ( compute and adjust ) information before using it. Even my old Trimble Survey Quality unit is only good for nearest three feet in elevation. Basically sub meter accuracy... So, you are mistaken in believing your Brunton Multi-Navigator is giving you anything under sub meter accuracy... This is the way it is and will remain this way for some time to come.
A better way to get good results with your projects, is to buy a Robotic Total Station and learn how to use it. They are cheap, fast and deadly accurate and only require one person to use...I can topo an entire 1 acre backyard with details in only 1/2 hour.
The copany that I work for looked at the Trimble system, but went with the Leica RTK something or other. I don't do survey work, but work closely in the office with people who do.
Badzook is right on with what I have been told and what I experience processing data in the office.
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OK buddy
