Precise Ordnance Map Data via an App?
Discussion
No sure if this is the correct place to post but here goes. I'm doing a job where a house has an exact floor height via ordnance maps/height above sea level. This has been marked on the site but upon looking at it, it seems high.
There's very little gravity to the manholes I'm tapping into so it must be right, but I was wondering if there's an easy way to check myself for peace of mind via an app?
There's very little gravity to the manholes I'm tapping into so it must be right, but I was wondering if there's an easy way to check myself for peace of mind via an app?
whatxd said:
No sure if this is the correct place to post but here goes. I'm doing a job where a house has an exact floor height via ordnance maps/height above sea level. This has been marked on the site but upon looking at it, it seems high.
There's very little gravity to the manholes I'm tapping into so it must be right, but I was wondering if there's an easy way to check myself for peace of mind via an app?
Not sure I understand what you’re asking, however surely you just need a normal dumpy level or equivalent if you’re just looking for the height difference between a floor level and manhole level? Apologies if I’ve got completely the wrong end of the stick.There's very little gravity to the manholes I'm tapping into so it must be right, but I was wondering if there's an easy way to check myself for peace of mind via an app?
OutInTheShed said:
Are you wanting to read the altitude from map data, or get a live height from the phone's GPS?
The county council's mapping on their rights of way (etc) portal may have some surveyed heights.
3D gps on phones can be a bit variable.
Some sort of live GPS, or even a similar device that can be purchased from somewhere.The county council's mapping on their rights of way (etc) portal may have some surveyed heights.
3D gps on phones can be a bit variable.
I basically want to sit it on the new house dpc level and see if it reads the same as the height that was with the planning application and is supposed to already have been marked up here on site (which is what I've set level to) just to make sure a mistake hasn't been made somewhere.
I've never seen these numbers myself, just been shown a line and told "that's the height you're going to"
OutInTheShed said:
Proper surveyors used to use DGPS systems, which could get to within a centimetre or so, comparing with a known point.
In about 1990, I had a lodger whose girlfriend was a surveyor.
I expect it's got cheaper and better since then?
Only if left for a very long time, like an hour or 4 hours for a properly accurate point using GNSS raw data then converted to Rinex. In about 1990, I had a lodger whose girlfriend was a surveyor.
I expect it's got cheaper and better since then?
Uncorrected GPS is pretty terrible for altitude, you've no chance.
You might get lucky and find one of the OS Benchmarks is nearby: https://interactivemaps.uk/os-benchmark-archive/ - none of these are calibrated against the modern mapping, they use GPS surveying.
I think your best bet is to find a surveyor with the appropriate kit for a few hundred pounds.
You might get lucky and find one of the OS Benchmarks is nearby: https://interactivemaps.uk/os-benchmark-archive/ - none of these are calibrated against the modern mapping, they use GPS surveying.
I think your best bet is to find a surveyor with the appropriate kit for a few hundred pounds.
What’s the actual aim of getting this information and what are you hoping to achieve?
If it’s not the right height how does that actually help you?
It sounds as if the problem is the height difference to the manhole is insufficient and surely if that’s a fact that’s a fact. It doesn’t matter what else is wrong.
If it’s not the right height how does that actually help you?
It sounds as if the problem is the height difference to the manhole is insufficient and surely if that’s a fact that’s a fact. It doesn’t matter what else is wrong.
If the levels are that critical and you obviously have some doubts about them then it would be definitely worth the money to get a surveyor in now to get some site levels done. Can’t remember what our last one charged but think it was around £600 but that was to do more than just check levels.
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