Comments and answers for "road network extraction"

Comment by lemzip on lemzip's answer

lemzip — Thu,10 Aug 2017 18:14:37 GMT

@redgeographicsThanks for the workbench.I have got it working but just a query,it looks like it is not including roads from OSM that should be within the aloted contour.Is this due to it being non node ended?

Thanks

Comment by redgeographics on redgeographics's comment

redgeographics — Mon,07 Aug 2017 11:20:06 GMT

Here you go.I'm using the OpenCage geocoder (removed my API key) to geocode an address,build a buffer around that and use that to extract data from OSM through the Overpass API (many thanks to @pimververfor figuring that one out).Then I'm adding some more data,built-up areas for The Netherlands,so I can make a guesstimate of the max speed in case it's not in OSM.The resulting road data is then cut in 4 slightly overlapping chunks to facilitate parallel processing.The NetworkCostCalculator does the actual work and I'm storing the drivetime distance as Z-values,then a ContourGenerator with some cleanup to end up with something that looks reasonably accurate and correct.
drivetime-sample.fmw

The problem is that it's still taking a fair amount of time to process,the parallel processing does make a big difference but it still takes my Mac 2 minutes to calculate an 8-minute drivetime contour and the processing time increases exponentially as the drivetime increases.

Comment by lemzip on lemzip's comment

lemzip — Mon,07 Aug 2017 11:09:32 GMT

@redgeographics
thats brilliant,thanks!

Comment by redgeographics on redgeographics's comment

redgeographics — Sat,05 Aug 2017 08:01:39 GMT

I'll try and dig it up on monday.

Answer by markat亚搏在线safe

markat亚搏在线safe — Fri,04 Aug 2017 22:04:31 GMT

I'd recommend validating the network first.All the FME network transformers assume that the network is clean.All intersections are fully noded and junctions occur at endpoints,not mid-point vertices.Use the NetworkTopologyCalculator to help validate the network and look for segments that do not connect

Comment by lemzip on lemzip's comment

lemzip — Fri,04 Aug 2017 14:34:56 GMT

@redgeographics

Any chance you could kindly share the workbench part for the OSM/network cost work?Still struggling with this.

Thanks

Comment by redgeographics on redgeographics's answer

redgeographics — Mon,31 Jul 2017 07:29:55 GMT

To add to @mark_1spatial's answer: I have recently done something quite similar,also using the NetworkCostCalculator and assigning educated guesses for the max speed in cases where it wasn't available in OSM.I've also used the Overpass Turbo API to extract only the roads in a certain radius (determined by assuming somebody driving at 20% over the overall max speed in a straight line for x minutes) around my starting point.

You may also want to look into parallel processing on the NetworkCostCalculator,it'll save you a lot of time.

看到 this threadfor some more discussion.

Answer by lemzip

lemzip — Mon,31 Jul 2017 00:29:44 GMT

sounds good mark,will give it a try.thanks

Comment by mark_1spatial on mark_1spatial's answer

mark_1spatial — Sun,30 Jul 2017 21:52:20 GMT

P.S.You'll need to reproject the OSM from geographic lat long for a measure of distances or consider custom transformer GeographicLengthCalculator.

Answer by mark_1spatial

mark_1spatial — Sun,30 Jul 2017 20:42:17 GMT

@lemziphave a look at the NetworkCostCalculator transformer.Set the Weight Type By Length and output cost by Z value.Then test the Z values for your distance.