Is there a way to shift all points in a project in relation to moving one point? Base shift sounds like the answer but it says this only moves the base and the rover, and won’t change existing points.
I have a boundary survey within a subdivision I need to shoot. After drawing it in Civil 3D I would like to shoot one of the monuments and shift all of the points in relation to that shot. Afterwards I would check the other monuments and if all is well stake out my corners.
If this isn’t possible I can’t think of a way to do it without either making two trips to the field or dragging my laptop out there to draw up the points after determining the monument locations.
That’s called localization, we are all hoping and patiently waiting for it
So what’s your method for getting around it? Two tripping it every time?
I use Field genius or I collect 2 points and add them as coordinates to the drawing
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I agree with David, this is the localization feature that you need. It’s in our roadmap and we’re working on it to make it possible in Emlid Flow. I’ve added your request as +1.
Also, you can align the drawing in Civil 3D and combine it with captured points as Michael suggested. I’d recommend you use several points for such alignment to avoid distortion errors.
You can download all data to a spreadsheet, calculate the dE, dN, dZ parameters between surveyed monument coordinates and “accurate” monument coordinates, then apply it to your dataset.
This works if it is a linear shift but true localizations have rotation. Just 1/10th degree of rotation over 1000ft is about 1.7ft.
Good call @michaelL ! If rotation is a concern, This method won’t work. But I presumed he averaged a position in the field, then the shift would be too small to have major implications in terms of rotation.
Rotation is a site condition variable. If monuments are not exactly where the record or CAD says they are or if something is missing and you are having to locate adjoiners then you start accruing rotation. These factors are agnostic to how the base point was acquired. Again is if all you are looking for is a base shift then your method is fine and as a matter of fact you can do a base shift in Flow.
Ideally, the monuments should be distant from each other too since it might affect the precision when rotating the data. And it’s always good to have a third one to perform a check.
Also, sometimes the data need to be scaled too.
Oh geez you had to bring up scaling… LOL. Yes, localizations have scaling but one thing we struggle with is scale factors. Surveyors and Contractors use grid here but Engineers like putting their CAD in surface coordinates… We require at least 4 points (encompassing the site) that are within 0.10ft XYZ on the localization. If we have 3 we can work with it and put in a construction benchmark but less than 3 and a registered Surveyor needs to be called out.
At the moment, you can only do a base shift in Flow at the very start of your survey (since only points captured after you perform the base shift are affected). This might be fine for a lot of people, but for our workflow it is not viable in many situations (where we capture local monuments either throughout the survey when we’re in the area or sometime afterwards depending on what time allows). We also often record the base and post-process it’s position afterwards (then would like to do a 1-point calibration). Currently, I don’t see a way to do base shift back in the office using the base autonomous position and the post-processed position. If there is a way, please let me know!
And just a question for clarification: what you guys are calling localization here, is that the same as performing a site calibration in other software packages?
You can do a base shift or localization (site calibration) in CAD afterwards as long as you have something to align to. I understand the Emlid base shift is different. Site calibrations are really for assigning geodetic coordinates to a grid point regardless of its coordinate reference system. There are specific routines in software like Civil 3D and Carlson Survey for network adjustments and localizations but quite honestly a 3-point alignment in CAD usually works just as well as long as you know your 3 points are good. Vertical rectification is usually a separate step for us regardless.
Right, I see. We don’t usually work in CAD software (in our environmental research), but mostly survey software (often Trimble Business Center, TBC) and GIS. Of course I can do the XY shift in a GIS, but the Z-shift is trickier.
One thing that has always been really easy in TBC is a one-point calibration using the (autonomous) base position and a post-processed base coordinate. However, an exported survey project from Emlid Flow does not contain the base point (which I find really strange), so that workflow, even in a spreadsheet, isn’t that straightforward and requires me to jump through hoops…
Localization in Field Genius is where to have 2 collect points and you reference- these 2 points onto 2 points of your cad drawing
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