From: john whelan <[email protected]>
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 someone.

From: "Laura O'Grady" <[email protected]>

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?

Ralph

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