Ralf Gerlich wrote:
This looks quite detailed. I'm not that familiar with the London area so would you say that there is a considerable amount of smaller streets missing in there?
You can see the source data here: http://www.openstreetmap.org/ there are roads missing, simply because the map is not yet complete, nor are they categorised. Once there's some more data, the segments are correctly joined into roads, and the roads are classified then we can be more selective about the roads we include in the scenery.
Even with not so much detailed streets - i.e., leaving all the back-streets out and having only freeways and mainstreets processed - the generation of scenery takes substantially longer than for the standard data. I have no numbers on this, but having to raise the resource limits in fgfs-construct considerably is quite a good indication.
Yes, the cpu limit was set as 120 seconds - I increased it to an hour and *still* had failures, so it's now set at 4 hours here just to be safe.
One other problem that'll probably become more serious with more detailed street-data is that the comparatively small streets not only produce lots of small triangles on the streets themselves but also raise the number of triangles on neighbouring polygons by splitting them. (Currently fgsd crashes on loading some of the more "full" tiles - possibly because of the sheer number of triangles; I will investigate further on that when I get the time)
I've not had that problem yet, but so far the data only covers a relatively small area.
I currently do not have any solution for that and I know that there have been discussions before, but perhaps having more detailed scenery now may be a good reason for the experts here to reconsider this topic.
We've just been discussing another problem on irc - the green texture isn't really appropriate for a city, but I left out the city areas since the texture it uses contains its own roads. I'm not really sure of a solution to this.
This may be solvable by automatically snapping endpoints and recombining shorter segments into longer segments.
It will be solved in future versions of the openstreetmap data - at the moment it just exports as lots of short roads with a start and end point, eventually these will be chained together to form longer roads.
Anyway recombination will only partially solve the problem, as on an intersection only pairs of participating line-segments can be joined. Perhaps we need a better way of making polygons from lines, much like the v.buffer operation of GRASS (http://grass.itc.it/grass61/manuals/html61_user/v.buffer.html).
At the moment I'l just converting the exported openstreetmap data to the tguserdef format, which I suspect is less than ideal. It may be worth having something that will be a bit more intelligent, and resolve some of these problems as it parses the data.
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