Best offset OptionsPosted by therock003 on June 4, 2019 at 7:24 pm
Tomorrow im going to survey a small plot with a lot of canopies and constructions surrounding it and unfortunately my helper is indisposed and im going at it alone.
What are my best options at offseting to get as many points as possible with the gnss unit and avoid revisiting with a total station. What practices do you use and what are the most convilenient and accurate ways to get those hard to reach points
- 8 Replies
- MemberJune 4, 2019 at 7:40 pm
A robotic total station that tracts well,would be your best instrument to use one man can run it and do the staking. If you dont have a robotic total station try using a 15 foot range pole to get higher than the canopy, equipment, and structures if possible. Cross chaining has always worked well for me. You can lay your tape out and take a shot at say 30 feet then come in and take another shot on the 15 foot. Just be careful not to move the tape. Or take offset shots at different angles if needed. I hate to take offset shots to property corners and fence corners, but I have in the past and probably will again one day.
- MemberJune 4, 2019 at 10:03 pm
Robotic total station is the way to go for sure.
But if that is not available, a handheld disto plus a GNSS rover can work in certain conditions. Certainly easier than taping it in while trying to hold the rover.
I have used 2-point distance offsets with this method, confirmed by total station later on, with good results. Depending on field software used, it may be easy to have the software calc the final point while you are shooting it, or not. Postprocessing can be annoying with offsets and calculated points…“…people will come to love their oppression, to adore the technologies that undo their capacities to think.” -Neil Postman
- MemberJune 5, 2019 at 5:11 pm
Without investing in new equipment? Multiple swing ties (ie. 3 min. where 2 for location and 1 for check) and good notes in the fieldbook. A camera is invaluable (especially one with an integrated GPS–see the Canon ones for a relatively cheap, feature packed one).
Everybody has time to do things twice–nobody seems to have time to them right the first time. It may take you an extra hour or so, but it will be done right.
- MemberJune 5, 2019 at 6:50 pm
“Everybody has time to do things twice–nobody seems to have time to them right the first time. It may take you an extra hour or so, but it will be done right.”
- MemberJune 6, 2019 at 1:37 pm
Many years ago now while I was a crew chief at a large regional firm another crew chief discovered the offset function on the data collector and he had an epiphany that he could set the gun in one spot and turn angles and use the offset function to enable him to “get the shot” without actually getting the shot. Hundreds of useless topo points. Offset LeftRight as well as InOut whatever distance he “thought” was correct and offset UpDown what ever he thought was correct. He was getting more acreage than anyone else by far and many thought of ourselves as inferior to this topo genius until we learned of his ruse. The topo’s he performed all had to be redone precisely because of the offset feature being misused.
- MemberJune 6, 2019 at 4:09 pm
Must be related to the crew chief I knew about ten years back who was too lazy to break out the total station when we needed a couple of topo features under the trees. He found out that if he ran under the trees as fast as he could with the network rover while frantically pressing the “measure” button, he could take a shot before he lost initialization. He would do that, then walk back out, regain init, then repeat as needed.
I figured something was odd because fire hydrants were landing in the street. I think the farthest flung shot was something like eighty feet…“…people will come to love their oppression, to adore the technologies that undo their capacities to think.” -Neil Postman
- MemberJune 6, 2019 at 5:05 pm
Ahh yes the old drag the Satellites into cover move.
- MemberJune 6, 2019 at 6:17 pm
You have to make sure the satellites have a good grip on the receiver before you try that. ????
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