ALWAYS keep GPS, and conventional coord systems SEPARATED.
You can place them on top of each other, so that they are IDENTICAL, at some points, but, you want to be able at any point to operate independent.
SO.... Base line 1, = POINT 1 to POINT 2.
Rename these. They are now 1G and 2G. (Or use 5001 and 5002)
Base line 2 is 9 to 10.
Rename these. 9G, and 10G (G denotes GPS) or use 5009, and 5010.
Now, you have numbers 1-4999 for conventional traverse.
Now, you can play with it. Make a MID point between 1G, and 10G. Call it 11G. Make a mid point between 1 and 10. Call it 11. Now, translate 1-11, placing 11 on top of 11G, Now, rotate 1-11, so that they are CLOSE to the other coords. Just play with it for a while.
Things like wrong prism offsets, and PPM on it will affect the BEST FIT of things.
This is only the GENERAL idea, of how to do it Manually.
IS GPS done via RTK, or Static? This changes the ellipse sizes.
You really need somebody HANDS on and in front of you doing all this. LEAST SQUARES will do this for you. But, your not quite ready for that.
ALWAYS keep GPS, and conventional coord systems SEPARATED.
While that was necessary in the past, it shouldn't be at present, at least not with current field & office software.
Total station observations can be reduced to grid, GNSS observations scaled to ground, or a custom projection may be used so that no warping of observations is needed.
Does this look right or does anyone have any input on how we should be doing this?
To give a typical surveyor answer, it depends...on the project goals, required accuracy, project location, type of gear being used, and which field/office software will be used to process the data. As Nate mentioned, least squares analysis is best practice when fixing control and mixing data from different sources with different standard errors.
However, if all you have is a data collector and must adjust in the field using compass rule, your diagram and method should work just fine.
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If you have the ability to tie points at the beginning and end of a traverse with GNSS, it doesn't take much more time to tag a few points along the way. Even if it's only a point or two in the middle, or every 2-3 points along the corridor, an hour or so of extra work will tighten things up a LOT when you go to adjust them.
When using Robot with GPS, I will typically set the backsight and occupation points with GPS at 60 or 90 epochs. I then average three GPS shots to calc a point to use on the Robot. The GPS and Robot data are together, but the data collector tells me which shot is GPS or Robot. It should also tell if there is a scale factor. We seem to get good numbers doing this.?ÿ
I am new to surveying over a distance of 200m with a total station/gps.?ÿ
Typically the work we carry out is Measured building surveys of houses/small buildings.?ÿ
We are now expanding our work to housing estates and there entrance road(s)
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My question is how to use a mixture of gps for controlling the total station on a road section.?ÿ
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I have made a rough paint image of what we have done.?ÿ
We have done to baselines from 1 to 2 and from 9 to 10 using GPS with 2x 180 second reads.?ÿ
Then we total station along this path from point to point.
The distance from Point 1 to Point 10 is around 1800metres.?ÿ
Does this look right or does anyone have any input on how we should be doing this??ÿ
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For info we are using a Leica TS16 and GS18 and using N4CE for reduction and processing.?ÿ
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TIA
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If you could get GPS on 6 that would be ideal.
We use Trimble so we gather all the data (including 4 sets of rounds on every control point) then combine it all in TBC. I??m sure you can do the same with Leica although their software often makes one want to throw their computer in the river.
Combining GPS vectors and Total Station data is readily done in most Least Squares adjustment packages. I use StarNet, but there are several others that will do it as well.
I don't know much about Leica software, data collectors or total stations, but there must be a simple way to set up a projection and get all equipment to survey in that projection.
That's been how GPS/Conventional has worked since I've been using them starting in the mid 1990's.
You haven't said if this is for setting out or for as-built survey. I'm assuming you are working in the UK. (US readers stop here - in the UK there are no property corners to find or set!)?ÿ If it is for setting out then your client should have provided you with the control stations used for the design survey. If it is for an as-built then the original control has probably disappeared. If it is for a proposed development then you need to ensure that you leave good reliable, recoverable control.
If you have been given control then use it. If it is a local grid then that might be random, might be National Grid (possibly truncated) or might be based on a single GPS point (accuracy unknown). In any case you can try and find a point you have been given, using the GPS if necessary to get within a decimetre or two and then poke around.
For the sort of arrangement you have outlined I would use the two GPS baselines as bearings, select one of the points, say 2 or 9 as the origin and valculate the EDM traverse between them. (Remember to convert the GPS values to ground, without scale factor.)
n4ce will handle this easily. You could either do it by traverse between the two points and then?ÿ use n4ce adjustment to close onto them or you could calculate the traverse separately as a one-off with one GPS station and bearing and then use other GPS baseline just as a check. (Or use the n4ce facility to transform the instrument traverse onto the two end GPS stations.
Remember that this is for housing, not a nuclear reactor, so closures at the ends within a cm. or two will be plenty good enough. It's probably better then to keep the traverse legs unadjusted (if the residuals are small enough) and just split the misclosure equally to each end by shifting all the EDM coordinates by a constant amount.
For most estates the critical part is ensuring the existing highway ties in, so I would normally use a couple of stations along there as the GPS reference, if I hadn't been given anything else. That way they will probably remain (as long as you set them clear of the new entrance) and the builder's groundworks contractor can reference them as necessary.
Not quite as simple as that! But Wendell won't thank me if I write a whole text book on here.
UK does have some determined boundaries which are coordinated, if that is the way the owner wishes to register their property, but generally we work on the "general boundaries" principle where features indicate the GENERAL location of the boundary without being specific as to exactly where it is. The Deeds accompanying the Title Plan may (or more commonly may not) provide additional description and/or some dimensions.
So a boundary might be shown on the Title Plan as being along a hedgeline. With no other clues it would generally be taken as the root of the hedge (and in areas with a strong prevailing wind the hedge moves over the centuries, as it seeds and grows new plants, and creates variations). The boundary may be marked with "T" symbols to show who is responsible for maintenance. If not then both parties share the cost. There might be a note in the Deeds stating that the boundary is, say, 3 ft. from the rootline.
Point features such as boundary stones do occasionally exist, but generally they would be centuries (millennia) old although I have?ÿ seen the odd newish one. Because the UK has a long history of land enclosure fences/hedges/walls are generally a more appropriate form of marking. Ground level blocks are occasionally used to delineate the edge of public land from private land when there is a good reason not to have a feature above ground level AND there is some form of right of access for the public onto the private land. (Most common where there is a public path across, perhaps, a private car parking area and the landowner doesn't want members of the public wandering around - the blocks would show where the path is to walk straight across.
The advantage of this system is that it is much cheaper for landowners in that survey is rarely needed for a land sale. There are surprisingly few arguments relating to boundaries (although lots about boundaries when they are used as a good excuse to annoy a neighbour you don't like!). We also have the advantage of very good mapping for 300 years so there aren't large tracts of unmapped terrain (although it doesn't all match GPS - but that's the advantage of "general boundaries" - you just correct it to "what it was supposed to be").
Ah ha! The top of this text has gone off the top of my screen - Sorry Wendell!
Not quite as simple as that! But Wendell won't thank me if I write a whole text book on here.
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Actually, Wendell might appreciate you "writing a book" for the forum. The more interesting content we users contribute, the more likely he will get more people reading the forum. It's definitely interesting to hear how it's done "over there" vs. my own backyard.
England gets a double-interest score for me, since U.S. common law originated there. Much of our boundary determination is based on common law principles.
There are surprisingly few arguments relating to boundaries
Around these parts; water front property is at a premium. A few inches (tenths of a foot, millimeters) potentially means a lot of money. The value of the entire property will be based on length of waterfront. This is usually determined by a surveyor. Not sure about UK, but it's hard to get surveyors to agree, around here. Hard to imagine projecting a hedgerow down to the shoreline, with any kind of accuracy...
