[pgrouting-users] polygons of drivingDistance

pgRouting pgrouting-users
1

Dear List,

I calculated the pgr_DrivingDistance for two costs (10 min, 20min). Then I used pgr_pointsAsPolygon in order to get polygons out of my points. Usually it works well, but sometimes the polygon with the "lower" cost covers some areas which the polygon with "higher" cost does NOT cover. Here is an example:

https://www.dropbox.com/s/tblyp7q4sp56sla/Error%20Alphashape.png?dl=0
(green=low cost red=high cost)

My goal is that polygons with "lower" cost are completely inside polygons with "higher" cost.

How would you approach this issue?

Best,
Jakob

2

Hi Jakob,

Are you using pgRouting v2.1 ?
If so, could you try to specify same alpha value (except 0) in both cases ?

[pgr_pointsAsPolygon — pgRouting Manual (2.1.0)]
http://docs.pgrouting.org/2.1/src/driving_distance/doc/dd_points_as_polygon.html#pgr-points-as-polygon

I guess that different optimal alpha value are used in the cases.

If specifying same alpha value doesn't solve the problem, please
create a ticket on
Github(Issues · pgRouting/pgrouting · GitHub) and upload
coordinate records(*.sql or *.csv)
to somewhere.

Regards,

Ko

2016-01-04 20:24 GMT+09:00 Jakob Miksch <jakob.miksch@posteo.eu>:

Dear List,

I calculated the pgr_DrivingDistance for two costs (10 min, 20min). Then I
used pgr_pointsAsPolygon in order to get polygons out of my points. Usually
it works well, but sometimes the polygon with the "lower" cost covers some
areas which the polygon with "higher" cost does NOT cover. Here is an
example:

Dropbox - Error - Simplify your life
(green=low cost red=high cost)

My goal is that polygons with "lower" cost are completely inside polygons
with "higher" cost.

How would you approach this issue?

Best,
Jakob
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Ko Nagase (長瀬 興)
Georepublic Japan
mail: nagase@georepublic.co.jp
web: http://georepublic.co.jp