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Might have to take the plunge and get into GPS Station Surveys
ChrisA replied 5 years, 3 months ago 18 Members · 54 Replies
Seems I’m in a bit of a quandary, but you’ve all been a massive help so far – thank you everyone!
If you take the time to master the use of total station. It will help with accuracies and time saving in building surveys. Especially in non perpendicular walls. As with a good Field to Finish Software. Picking up the features and internal walls will automatically be drawn up and elevations will automatically be drawn as well as linework. however a word of warning, setting up your inital templates and workflow will be frustrating and time consuming, as you have to decide what standards to follow etc, but the time savings from then on will be worth it.
- Posted by: ChrisA
Hi Mark (Silver this time!),
Are they cheaper here then? That’s nice for a change!
That’s all very useful information, thanks for typing!
I kind of assumed that a base and rover would be needed to get under trees – I’m so sorry I don’t speak with the experience you all have! Over here, I visit site which huge tree canopies, though never high density from a building perspective. I just didn’t want to turn up at a site, having arranged the date/time and have to turn around and say, “sorry, I can’t get any satellites”.
I think I’ve got your PM, thank you very much for that, I’ll certainly get in touch with him!
GPS doesn’t work under trees or near buildings. And be very sceptical if you are in these conditions and the controller assures you that everything is fine and accurate.
Also I think you may still be confused about the base options –
Base and Rover – need 2 receivers, no subscription
Network RTK (aka VRS) – only need 1 receiver, but need to pay annual subscription for the corrections by mobile phone.
Nearly everyone uses the second option now (in UK). apart from a few particular reasons that I don’t think will apply to you.
Neither is better or worse as regards working under trees etc;
You might find that you can do what you need with a manual total station. Can get a good one for ?2000 secondhand.
Reflectorless shots for the buildings, walls etc; and get a bipod or similar for spot levels. Bit of walking back and forth but might not be too bad for small surveys. Can be used for setting-out as well. On a clear site it’s easy to use reflectors etc; for one man non-robotic operation.
I’d partly agree with Squowse -but working by yourself with a manual total station isn’t easy of you want to get topo over the whole site. For each shot where a ground level is needed you would have to move the target, go back to the instrument and observe. If you can afford it you are much better off with a robotic unit.
Remember that with a total station you can run the control into the building and fix a number of points to help tie up your internal taped measurements – saving a huge amount of time in old buildings where nothing is quite straight. A traverse down each corridor and a couple of shots into some rooms make everything a lot easier (assuming you aren’t going to splash out on a scanner!)
The only benefit you might get from GPS for your sort of work is that you could establish the site reference point onto OS datum easily, without running to the nearest benchmark, but I suspect most of yours are to a local datum anyway.
Without any survey experience don’t buy off the internet – you need a dealer support for the gear and if you buy through a dealer you can be assured that spares and service will be available for some years. (Christ Lambrecht is probably getting rid of his R6s for the same reason that ours will be replaced – Trimble have stopped providing spares for the early ones).
GPS doesn’t work under trees or near buildings. And be very sceptical if you are in these conditions and the controller assures you that everything is fine and accurate.
I’d like to temper that remark somewhat. GNSS will work, more or less, under some tree cover and near buildings – to a degree, at least. But the coordinate quality will be degraded and it will quit returning positions altogether when the obstructions are enough. Which doesn’t have to be all that much.
A common misconception is that the base collects satellite data and transmits it to the rover. Not so. Both base and rover need to be collecting data from common satellites to get positions. When the data at either becomes to noisy, or the number of common satellites drops below the minimum, fix is lost.
Without any survey experience don’t buy off the internet – you need a dealer support for the gear and if you buy through a dealer you can be assured that spares and service will be available for some years.
I think that is very good advise.
- Posted by: Dave KarolyPosted by: Nate The Surveyor
Chris,
Where are you? England?
And “?20k” is that euro pounds?
What kind of surveying do you do? Boundary? What kind of title do you have over there?
I’m on my phone typing here.
N
I think in the U.K. Boundary Surveying and Engineering Surveying are separate professions.
There is very little boundary surveying in the UK because there is very little land ownership. People own the buildings but they oftentimes do not own the land. We have boundary surveyors in the US due to the Constitution (the 4th and 14th Amendments) that you can’t lose land without due process. Here’s an article explaining the situation: https://www.newstatesman.com/life-and-society/2011/03/million-acres-land-ownership
- Posted by: True Corner
I think in the U.K. Boundary Surveying and Engineering Surveying are separate professions.
There is very little boundary surveying in the UK because there is very little land ownership. People own the buildings but they oftentimes do not own the land. We have boundary surveyors in the US due to the Constitution (the 4th and 14th Amendments) that you can’t lose land without due process. Here’s an article explaining the situation: https://www.newstatesman.com/life-and-society/2011/03/million-acres-land-ownership
Very misleading, especially the article quoted. For all practical purposes “The Crown” will never take back land so it is owned by those who have purchased it. Similarly, in the US, you might own the land but if you declared “independence” for your plot then your authorities would step in and point out that “your” land was “owned” by the US.
The UK system works on the basis of “General Boundaries”. By and large that works well. For the vast majority of land sales no survey is needed and the party purchasing just inspects to see that the apparent boundary on site matches the plan. Most times they don’t even do that, which is when boundary disputes can arise.
Since the UK doesn’t recognise surveying as a “reserved” profession, unlike medicine, then there are no restrictions on practising. It would be correct to say that most surveyors dealing with boundaries and not engineering surveyors and vice versa, but that is a matter of experience in the different fields.
Some of us deal with both.
The UK has a far, far higher percentage of inhabitants owning their own property than most of Europe.
The following is a better article: https://libcom.org/news/article.php/land-ownership-right-roam-uk-10032006
My inlaws owned their building but paid a 99 year leasehold on the land which according to them is quite common. Additionally you don’t have a land registry.
It’s quite a bit different in the UK and the rest of the world for that matter.
- Posted by: True Corner
The following is a better article: https://libcom.org/news/article.php/land-ownership-right-roam-uk-10032006
My inlaws owned their building but paid a 99 year leasehold on the land which according to them is quite common. Additionally you don’t have a land registry.
It’s quite a bit different in the UK and the rest of the world for that matter.
I think that website has a bit of an agenda to say the least!
This is the website for England and Wales land registry. I can assure you it very much exists.
https://www.gov.uk/government/organisations/land-registry
leasehold properties do exist but they are rapidly falling out of favour. there are government acts to enable occupiers to buy them out.
Main difference is we don’t have a “point of beginning” – the land was carved up long before that was thought of. So boundaries are very unlikely to be able to be re-established.
There are lots of different types of surveyors, but chartered surveyors and solicitors (lawyers) deal with property transactions. Our type of measuring equipment is not much use to them, although the square metreage of a building will count for a lot in terms of it’s value. They just measure it up with a tape or disto.
In general the boundary is where the fence or wall is. If you want to argue otherwise you’re going to need some good evidence and lots of money for lawyers. Funnily enough it is rarely a problem.
- Posted by: squowse
Our type of measuring equipment is not much use to them, although the square metreage of a building will count for a lot in terms of it’s value. They just measure it up with a tape or disto.
In general the boundary is where the fence or wall is. If you want to argue otherwise you’re going to need some good evidence and lots of money for lawyers. Funnily enough it is rarely a problem.
Tapes and Distos are OK for internal work (sometimes). There are different types of Chartered Surveyor, qualified in one or more of the 6 sectors within land and buildings, so some of us use total stations and GPS as our main tools.
Whilst the General Boundaries rule serves the UK well (hard to argue when the boundary is “somewhere within the wall”) when arguments do kick off they do so with a vengeance. I have one dispute, started in 2015, which still hasn’t quite reached finality and has already produced survey fees of ?40,000. What the lawyers have pocketed I hate to imagine. All over 50 yards of common boundary – a very well-off area in Surrey, UK.
Sorry for the delay all, it’s Friday night and I finally got round to responding, it’s been a long week, though I actually managed almost a whole day off today, that was nice!
Sireath – Thank you for that, really kind. I think it will be frustrating at first and there’s no doubt a lot of time will be used up getting things set up. I’ve probably said in a previous post, but I’m only doing this because the local surveyors don’t really like small jobs and understandably have to price them similar to a medium/large sized job. It’s often an issue that I want the information for greater accuracy and more useful drawings, but the client isn’t prepared to pay for it. It’ll no doubt take some time, but hopefully time I can gradually recover over…ummm, time.
Squowse – Funnily enough the unit I saw, that I thought would get me under trees (using a GPS system) has been confirmed as not working as expected – and by all people, the seller! Quite honest of them and glad I’ve got your comments to confirm this.
Thank you very much for clarifying my confusion, I’m so sorry to you and everyone for writing these seemingly silly questions, but over on this side of the pond there’s very little information. Understandable of course, as I have knowledge about how I perform my work, and I’m unlikely to give that up for free, for fear of creating more competition!
About the idea of a ?2k manual total station, I’ll a little restricted on have a second pair of hands at conveniently short notice, so for times sake, a Robotic Total Station would be best…just not the best for my wallet. On the bright side, at least any borrowing interest will be tax deductible…but it’s still my actual money that’s being spent! Thanks again for your comments, it truly is invaluable.
Chris Mills – I think you’re right re the Robotic unit, despite the cost increase. That also sounds superb that I can connect it with internal measures. You’re right again re local datum sufficing, I’m not carrying out any large scale builds, normally just a house, or two at most, and mainly extensions to existing buildings.
Quite right about buying off the internet, I’m looking for local outlets first, but nationwide for general cost research. Oddly one has admitted that they can supply me with a Robotic Total station, however it’s very old and parts would be difficult to attain if there were problems…quite honest for a body that wishes to sell something. That’s a really useful headsup about Trimble, I’m sure that’s a real disappointment for many. Thank you again!
Norman Oklahoma – Really appreciate you weighing in, I was under the (wrong) impression that the base need only to be in clear line of sight to sats, and then knows the position of the rover. From the outset I’ve respected and appreciated that this isn’t an area you can casually drop by, and everyone here has indirectly conveyed that, quite rightly.
Thank you Norman, really invaluable info.
True Corner – Quite right, it is a much smaller area, however we have Ordnance Survey to thank for preliminary plans of every corner of the UK (as it’s quite small, it was relatively easy). These are generally used to illustrate the extents of the ownership boundary, I would happily upload one as a sample if anyone is curious.
Chris Mills - Following on from your later comments, I’ve been involved in land purchases and despite the accuracy available to us, we still refer to the old Land Registry plans as ‘gospel’. Clients assume that precise drawings are required, but often the revision of an old 1:1250 scale plan is sufficient and actually the only acceptable format. It’s a funny country isn’t it.
You’re also right about the UK having a greater quantity of property owners, I think Germany is the highest in Europe, that’s partly due to property not being used so much as an income source. That does need to be confirmed though, as I’m only going on memory.
Chris Mills – Sorry, just noticed you’re in this country, hello! Couldn’t agree with you more, I’ve dealt with party issues and it’s just a specialist area. In principle, say in a terrace, you own half of the wall. That’s simple enough isn’t it, but like you say, in situations where the boundary is more vague, clients and owners will only end up lining the pockets of the legal beagles to fight out disputes. It’s a strange world…or rather country.
The base should be as open as possible. Base and rover need common satellites so if the rover is marginal it may work if the base has a lot more satellites available.
U.S. boundary law is like U.K. boundary law with an inadequate scientific element thrown in to make it interesting. Much of the U.S. is arid and larger tracts so it doesn’t lend itself as well to walls and hedges.
Have you thought about renting survey kit? Or, short term renting a network GPS receiver and owning a robotic total station? That way you could establish control stations with OSGB36 co ords and ODN heights with GPS as a basis for surveys with the TS. If you just do floating surveys with a TS you can’t tie into public sewer heights, title deed plans etc. Don’t underestimate the cost of additional software and the time it will take to get familiar with it, the hardware is only half the story.
For the sort of surveys a small architect does, most would be on a local datum. As long as you have the height difference between your drainage outfall and the local sewer that generally does. Whilst it is true that floating surveys won’t tie in with title deed plans, in this country GPS probably won’t either! Far too accurate for a mapping system which originated in the need for the English Army to know how to get at the French and the Scots (sorry, no offence Artie Kay!)
Comment on software is very appropriate: that is where the real learning curve lies.
I’d like to add a few things if I may:
First of all, that GPS that you shared the link for is outrageously expensive for a GPS located in the UK. If you look on Ebay you’ll see them pop up every now and again for well under 2000 quid for a Leica 1200 system.
Secondly, that unit is a base and a rover system. You’ll only need the rover plus some sort of NTRIP system in the UK. South east England (Kent I assume??) is quite populated, and from my time wandering around Maidstone/Sevenoaks/Otford the mobile phone reception from O2 was amazing. This is critical when using NTRIP. You really only need a base station when you’re starting from scratch with nobody to help you find your location. With NTRIP, you’re essentially using someone else’s base station as a reference point. And these days a lot of them are free.
Thirdly, you sound like someone who is doing a lot of “detail surveys” so you can figure what is actually is there, so you can then design a new structure and knock down the old one. As someone said earlier, you might be better off using a total station for that sort of work. Again, from the time I spent in your neck of the woods, you guys like your “huddled together” terrace houses and hedgerows. Without clear line-of-sight access to the sky, your GPS isn’t going to get the job done for you. Not at all.
Doing detail surveys means that you care more about what is there as opposed to where in the world it actually is. If you actually do need to know where in the world it actually is, then you sound like you’re not qualified to do that work in the first place. So if you don’t actually care where it is, then just get your orientation from the kerb/curb line and align it with Google maps so your shadow diagrams will be right.
This is a shockingly bad way to do things and I personally would never dream of doing it like that. But if you genuinely don’t care “where the land is” then go for it. If you think it will matter for some reason, then buy a rover with NTRIP, use it to put in two marks at either end of the street accurate to 10mm or 20mm, then buy an older reflectorless total station (maybe a Leica 1100/1200 robot) and traverse off those two marks. You’ll get all of your kit in the UK for around the same price as that GPS from Sealand.
For example, the rover below it would be closer to what you need……but still too expensive:
http://sealandsurvey.co.uk/leica-atx-1200-gps-network-rover/
But if at any point during the project your information needs to submitted to ANY form of government office to be added to the cadastre, then you shouldn’t be in here asking for advice on equipment. You should be asking about where to find a qualified surveyor in south-eastern UK. Don’t your real estate agents handle cadastral surveying in the UK?
Mick
P.s. Germany has the lowest rate of home ownership anywhere in the European Union. True story! Germany itself is rich. It’s people are paupers. Low wages and high taxes will do that.
One more thing…
Even I, on the west coast of the US, know what Sealand is and something of it’s history. While I have no personal knowledge of Sealand Survey I don’t think I’d be comfortable spending real money buying from a dealer that self-identifies as being Sealandish.
Sealand survey is a reputable company on the border of North Wales. Nothing to do with the Sealand in the Thames.
- Posted by: Micheal D'Aubyn
I’d like to add a few things if I may:
First of all, that GPS that you shared the link for is outrageously expensive for a GPS located in the UK. If you look on Ebay you’ll see them pop up every now and again for well under 2000 quid for a Leica 1200 system.
Secondly, that unit is a base and a rover system. You’ll only need the rover plus some sort of NTRIP system in the UK. South east England (Kent I assume??) is quite populated, and from my time wandering around Maidstone/Sevenoaks/Otford the mobile phone reception from O2 was amazing. This is critical when using NTRIP. You really only need a base station when you’re starting from scratch with nobody to help you find your location. With NTRIP, you’re essentially using someone else’s base station as a reference point. And these days a lot of them are free.
Thirdly, you sound like someone who is doing a lot of “detail surveys” so you can figure what is actually is there, so you can then design a new structure and knock down the old one. As someone said earlier, you might be better off using a total station for that sort of work. Again, from the time I spent in your neck of the woods, you guys like your “huddled together” terrace houses and hedgerows. Without clear line-of-sight access to the sky, your GPS isn’t going to get the job done for you. Not at all.
Doing detail surveys means that you care more about what is there as opposed to where in the world it actually is. If you actually do need to know where in the world it actually is, then you sound like you’re not qualified to do that work in the first place. So if you don’t actually care where it is, then just get your orientation from the kerb/curb line and align it with Google maps so your shadow diagrams will be right.
This is a shockingly bad way to do things and I personally would never dream of doing it like that. But if you genuinely don’t care “where the land is” then go for it. If you think it will matter for some reason, then buy a rover with NTRIP, use it to put in two marks at either end of the street accurate to 10mm or 20mm, then buy an older reflectorless total station (maybe a Leica 1100/1200 robot) and traverse off those two marks. You’ll get all of your kit in the UK for around the same price as that GPS from Sealand.
For example, the rover below it would be closer to what you need……but still too expensive:
http://sealandsurvey.co.uk/leica-atx-1200-gps-network-rover/
But if at any point during the project your information needs to submitted to ANY form of government office to be added to the cadastre, then you shouldn’t be in here asking for advice on equipment. You should be asking about where to find a qualified surveyor in south-eastern UK. Don’t your real estate agents handle cadastral surveying in the UK?
Mick
P.s. Germany has the lowest rate of home ownership anywhere in the European Union. True story! Germany itself is rich. It’s people are paupers. Low wages and high taxes will do that.
No free NRTK in UK as yet.
No measured “cadastre” either. Certainly not with coordinates.
Here’s where you should start. I’m sure there is an RTK correction stream you could use. Some are free here in US.
https://london.craigslist.org/eld/6745377913.html?lang=en&cc=us
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