At street map level, I have the data, but I don't think I've a license to use it for this purpose (conceivably, I have no license to use it for any purpose ...). Also I'm not completely certain of the mapping from latitude and longitude to OS grid references.
At the geological level, this large image (http://www.chiark.greenend.org.uk/~twomack/goo.jpg) is obtained by flood-filling with blue everything connected by a path below 57m to the sea. It's clearly fiction; you don't get islands with that low relief and a sea-bed going down that shallowly, but I don't know where I'd begin in simulating wave erosion. It might be more accurate in the regions beyond the straits of Bath and of Llandogo, where the waves won't penetrate.
The two islands sticking up by the Cheltenham escarpment are the two hills of Gloucester; the limits of the water in the north-east are Kenilworth and Offchurch, in the north-west it flows under Ironbridge and Stoke becomes a harbour town. Chippenham is the little island in the south-east part of the sea; the straits drown Bath. Chipping Sodbury and parts of Filton survive, and there's an isthmus with Portishead on it. I'm afraid Bristol's gone.
The labelled wet image (5M PNG) (http://www.chiark.greenend.org.uk/~twomack/wet-labelled.png)
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timeasmymeasure
I don't have the software to distribute, but I've got the capability
Date: 2005-03-22 08:21 pm (UTC)At the geological level, this large image (http://www.chiark.greenend.org.uk/~twomack/goo.jpg) is obtained by flood-filling with blue everything connected by a path below 57m to the sea. It's clearly fiction; you don't get islands with that low relief and a sea-bed going down that shallowly, but I don't know where I'd begin in simulating wave erosion. It might be more accurate in the regions beyond the straits of Bath and of Llandogo, where the waves won't penetrate.
The two islands sticking up by the Cheltenham escarpment are the two hills of Gloucester; the limits of the water in the north-east are Kenilworth and Offchurch, in the north-west it flows under Ironbridge and Stoke becomes a harbour town. Chippenham is the little island in the south-east part of the sea; the straits drown Bath. Chipping Sodbury and parts of Filton survive, and there's an isthmus with Portishead on it. I'm afraid Bristol's gone.
The labelled wet image (5M PNG) (http://www.chiark.greenend.org.uk/~twomack/wet-labelled.png)