[HOT] The Economist Title to Come July 16th

Ralph Aytoun ralph.aytoun at ntlworld.com
Thu Jul 21 13:51:17 UTC 2016

From: john whelan <jwhelan0112 at gmail.com>
>That I think we have some expertise in doing.  .......
> ......I suspect with some GIS input we might be able to improve the 
> process.

Laura is quite correct. Our OSM is not technically accurate enough to be 
used in legal argument. For Land Registry it requires a Chartered Land 
Surveyor to carry out a survey on the ground using theodolite and linking it 
to the fixed local triangulation beacons. Our satellite imagery is  floating 
.... it is not adjusted accurately to fixed triangulation points on the 
ground so we have the problem that each time the background imagery is 
updated the features already mapped no longer fit.

If we can gather enough historical imagery going back far enough we could 
prove ongoing occupation and buildings on a piece of land but that will not 
prove ownership, only a length of consistent occupation/habitation by 

>From: "Laura O'Grady" <laura at lauraogrady.ca>

>From what I understanding surveying is much more precise than mapping from 
>sat imagery. I believe what we're doing is referred to as >topological 
>editing or digitizing and is generally considered to fall within the domain 
>of GIS. The two fields are now starting to crossing >over in what is known 
>as geomatics.

>If there's precedent for land surveyed data then HOT mapping might not be 
>considered to be accurate enough.

+1 Laura. Quite correct, tracing from unfixed satellite imagery and GIS is 
not going to replace 'on the ground' survey from triangulation points.

And even then ... if the government of the day chooses to ignore or nullify 
any registration of land then there is very little anyone can do about it. 
Rural Africa has a long way to go before we can think of any kind of 
security of land tenure for local habitants. That is unfortunate but a 
reality of life there.

Our task at Openstreetmap is to put them on the map so that aid agencies 
know they are there and can help alleviate some of their problems. 
Unfortunately by putting them on the map also alerts others to the fact that 
they are there and their intentions may not be as honourable as ours. For 
that reason Missing Maps tends to map areas that are identified as in need 
of help and this means that the good they derive from being on the map 
outweighs any downside.

Thanks for that interesting idea John, but I do not believe it is possible 
through Openstreetmap.

Anyone else with ideas for a solution or thoughts on this?


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