Hi there,

Thomas Förster wrote:
> Am Dienstag 20 Februar 2007 09:57 schrieb Dene:
> 
>>Hi Chris
>>
>>>Are the landcover db boundaries vector-based? If they are then there
>>>is no reason why the terrain could not be created more accurately at
>>>those boundaries, for example between land and rivers.
>>
>>As far s I know, at the moment the land cover is triangle based. ie each
>>triangle in the processed terrain is assigned a landcover texture from
>>sea, ocean etc to urban etc. This and the simplification of the terrain
>>& elevation error limits cause the landcover boundaries to be distorted.
> 
> Depends on what you see as land cover db. The default terrain is created from 
> SRTM for elevation data and vmap0 for land use (not 100% sure) and the line 
> features like rivers, roads, railways...
> 
> Unfortunately vmap0 only codes the course of the line features, not their 
> width. Thats why rivers are uniformly 25 meters wide (except where they are 
> wide enough to be coded as polygons in vmap0, mostly estuaries), roads are 10 
> meters, ...

Is there a free data source that can replace vmap0, that has accurate
terrain-type boundaries?

> That means there is no way to improve the river shores from the original data 
> alone. Several people (including me) have created small parts of scenery by 
> digitizing scanned survey maps, which tremendously increased visual 
> appearance. Yet time consumption (~30h for a 10x10km area from 1:25.000) and 
> unclear copyright/terms of use issues don't let it scale well.
> 
> Anyway, Martin Spott already created a data base to collect vector data 
> contributions and provide a single base for scenery creation.
> 
> http://www.custom-scenery.org/Landcover-DB.212.0.html


Kind regards,

Chris Wilkinson, Brisbane, Australia.

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