I know the preferred method to locate your base is to collect a few hours of data the day before and then submit it to opus and key it in when you start your base and your work.
Many times however I do not have time for this. I do a lot of small projects where I may be in and out in half a day and it is not feasible to collect data the day before. In these scenarios the option is to start the base using a here and log data. You then stakeout your points and you are not really putting them exactly where you want due to errors in the here base position. You can apply the opus location for the base location after the fact in TBC and know where exactly you put things which works for our needs but I was wondering any methods if any to better locate the base? VRS is not an option in the area we are working in.
I don't understand how you would have points to stake out before control has been established on a site. I think the approach you should take is to find out where the established project control points are.
In an ideal situation you are correct. The stakeout positions for what we are doing are not very critical. If we are within 5-10 feet of the project design stakeout location then all is good but we do need to know where we put things. If we don't do it before we set up the base we do need to correct the data to opus after the fact in TBC so that we report true locations and elevations.
I was just wondering what methods I could use get a better location for the base than using "here" when we are in a hurry. For example what if I logged WAAS data for 30 minutes or so and then saved that point and used it for a base location? Using "here" we have seen shifts up to 6' once corrected to opus. This is acceptable to us but I was wondering how to do better.
Yes. Calibrate (localize) or occupy existing control.
Can you average epochs for your "here" base position?
If so, do this for ten to fifteen minutes and then start your survey.
> Can you average epochs for your "here" base position?
>
> If so, do this for ten to fifteen minutes and then start your survey.
I don't think so. When you click here it instantly starts up. Basically this is what I was wanting to do was average my base location.
Isn't a 4 hour session sufficient for Opus?
> Isn't a 4 hour session sufficient for Opus?
Yes it is but the data usually isn't available until that night.
For example I roll up to job site at 7 AM. I start base logging and do my RTK stakeout and may be done and gone by noon. The opus data is not available until that night which for all practical purposes means if I want to use the opus location for the base before I stakeout I need to collect the data for opus the day before I do my stakeout.
The current system collects enough data for opus and the positions I stake out can be corrected in TBC after we get the opus solution.
I was just trying to figure out a way to better locate the base to minimize the errors of my stakeout points.
I don't see a lot of options, as mentioned above, you need control. Published points nearby where you can set-up or Opus. I was under the impression that the corrected data was needed for deliverables, so waiting 24 hours for the reply should not be much of a problem?
Can you guarantee that a here solution is always within 5-10 ft? I wouldn't.
Can you set up a rtk intuitcom bridge to bring cellular via radio to your project area and then use a RTN position as your base position. Or do it all with the RTN via intuitcom bridge if you are meeting accuracy specs.
> I don't see a lot of options, as mentioned above, you need control. Published points nearby where you can set-up or Opus. I was under the impression that the corrected data was needed for deliverables, so waiting 24 hours for the reply should not be much of a problem?
>
> Can you guarantee that a here solution is always within 5-10 ft? I wouldn't.
Yes waiting 24 hours for opus to make the corrections for the deliverables is fine. I was just looking for ways to minimize the adjustments as I stake out the points before I get the solution. Once I get the solution I am able to correct and know exactly where the points are but they are often not exactly where they are supposed to be per the original plan due to errors in the base here location.
5-10 foot shift is no problem even 20 foot probably wouldn't be either as long as everything's relative position is correct. That being said I am just trying to figure out a better way of doing things to make my stake outs more accurate.
How would one tie to existing control? Say for example I know where a benchmark is. I don't want to set my base up over it because it will get stolen. Can I set my base at a random location, take a shot on the benchmark with a rover and then somehow correct the base position? I am sure this all can be easily done in TBC but I was talking about doing it in the field on the fly.
> Can you set up a rtk intuitcom bridge to bring cellular via radio to your project area and then use a RTN position as your base position. Or do it all with the RTN via intuitcom bridge if you are meeting accuracy specs.
I don't think so. In many of these areas there is zero cell coverage and the closest cors station is 100 miles away.
You would have to calculate the delta's BM surveyed Vs. BM published. Power off the base, enter a new point Here-Adj. Based on the calculation. Restart the base with known point (Here-Adj), check tie at your Benchmark or another if you can. If all looks good, go stakeout.
What about using DGPS, like a Trimble pathfinder?
> In an ideal situation you are correct. The stakeout positions for what we are doing are not very critical. If we are within 5-10 feet of the project design stakeout location then all is good but we do need to know where we put things. If we don't do it before we set up the base we do need to correct the data to opus after the fact in TBC so that we report true locations and elevations.
>
> I was just wondering what methods I could use get a better location for the base than using "here" when we are in a hurry. For example what if I logged WAAS data for 30 minutes or so and then saved that point and used it for a base location? Using "here" we have seen shifts up to 6' once corrected to opus. This is acceptable to us but I was wondering how to do better.
I would not trust an autonomous position, which is what you are getting with the 'HERE' button, to be within 5 to 10 feet.
Just my 2 cents
We use Trimble's IBase and VRS
But its not as accurate as we would like for Cadastral work - where our own RTK base is prefered.
It is possible to use IBase to get an initial position for the base station and go from there
You can use Trimble's RTX post processing service from inside TBC 3.1
Just log 1 hour of static data and you can send that straight away to RTX through TBC and a Survey Grade position ( a few centimeters) will be sent back instantly. Alternatively if you are lucky enough to have R10s then subscribe to Omnistar or Trimble real time RTX and you will get an accurate positions in real time
I Don't Understand
You have coordinates for items to be staked out, but have no coordinates for any existing physical point on site?
Just where the heck are your stakeout coordinates coming from?
Paul in PA
I Don't Understand
> You have coordinates for items to be staked out, but have no coordinates for any existing physical point on site?
>
> Just where the heck are your stakeout coordinates coming from?
>
> Paul in PA
A client might need random drill test holes on a parcel of land. Whether the starting point of the drill is here or there does not really matter, what matter is spacing between drill holes and exact final NEH.
(Just an example.)
