A short tree walk in Mayow Park

[Tim Lund]

Just a few metres in a South Easterly direction



Either that, or I need to make a couple of adjustments to the parameters for converting Grid References to latitude and longitude

Source here

[Tim Lund]

I may need to apply the Helmert transform

[art4]

Tim

I've just been reading about Helmert transformation since you posted. I don't understand can you explain it to me in an easy way please?

[Tim Lund]

Tim

I've just been reading about Helmert transformation since you posted. I don't understand can you explain it to me in an easy way please?

No.

Don't think I'm being unhelpful - I wish I could, but as explained on this website

Some people have asked me about converting between latitude/longitude & Ordnance Survey grid references. The maths is extraordinarily complex, but the Ordnance Survey explain the resulting formulae very clearly in Annex C of their Guide to coordinate systems in Great Britain.

So go find in Annex C of 'A guide to coordinate systems in Great Britain' here

But stick to the easier bits, and you'll find some new facts with which you will be able to amaze your friends

Relative to the centre of the Earth, a point on the ground can move as much as a metre up and down every day just because of the tidal influences of the sun and moon.

The relative motion of two continents can be 10 centimetres a year, which is significant for mapping because it is constant year after year – after 50 years a region of the earth may have moved by 5 metres relative to a neighbouring continent.

Many other small effects can be observed – the sinking of Britain when the tide comes in over the continental shelf (a few centimetres), the sinking of inland areas under a weather system ‘high’ (about 5 millimetres), and the rising of the land in response to the melting of the last Ice Age (about 2 millimetres per year in Scotland, up to 1 centimetre per year in Scandinavia)

Did you feel the Earth move?

Anything for a chance to link to Carol King

[youtubes]https://www.youtube.com/watch?v=sGdyMgvRNEg[/youtubes]

[Tim Lund]

Feeling much better with my Helmert transform applied



My favourite tree, right on target. Well, maybe a few metres to the north. Good enough, I reckon.

And this is what the Excel formula looked like

{=aXYZToLatLng(aHelmert(aLatLngHToXYZ(I6:J6,TRUE),TRUE),TRUE)}

Hope that helps

[Eagle]

Tim

I a,m baffled. Why not tall trees. Is this discriminatory ????? What about Equal Tree Rights

[Tim Lund]

Eagle - since the data set - for all trees which are the responsibility of the Council - included details of the height, spread and species as well as location, I could prepare such maps with any level of discrimination you might ask for, although I'm not saying I would. But, with Chalara ash dieback spreading across the British Isles, I can imagine one just showing them could be of wider interest.