On 05/04/15 12:53, image93 wrote:
Hello,
Below, the computational region setting :
--------------------------------------------------------------------
projection: 99 (Lambert Conformal Conic)
zone: 0
datum: towgs84=0,0,0,0,0,0,0
ellipsoid: grs80
north: 7037330.05419347
south: -0.94580653
west: 0
east: 798655
nsres: 1
ewres: 1
rows: 46916
cols: 5324
cells: 249780784
--------------------------------------------------------------------
When i modify the resolution nres/ewres from 1 to "150", i have no longer
error message. But when i try a process with a resolution with a value <
150, the process is endless...
According to you, the results generated at this resolution (150) would be
relevant? valid?
I loaded the output vector into qgis. The results are seem incoherent. The
curves show that we can go in 15 minutes on the other side of Paris! In
reality, From my starting point we would go much further toward toward north
than south west...
I use OSM data. I edited and populated the max speed field thanks to the
value of another filed (type of road).
How to explain this incoherence? Due to v.isochrones? Due to resolution? Due
to input maxspeed values ?
Difficult to say without the data. At this stage, v.isochrones should
probably be considered beta, notably because of a significant rewrite,
so it might be v.isochrone's fault. Then again, as I mentioned in my
response to your other mail, I'm not sure that you are calling
v.isochrones with the correct input data.
Could you make your data available off-list, so that I can experiment
with it myself ?
I am annoyed because it seems impossible to generate the results for a
better resolution than 150.
That is not normal, As I told you offlist, I've been able to run
v.isochrones in a 152,198,630 pixel region on the entire OSM network of
Belgium within 1-2 minutes depending on settings. That's double the
number of pixels of what you would get with a 2m resolution.
Moritz
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