[Tile-serving] [osm2pgsql-dev/osm2pgsql] Generalization: discrete isolation: meaning of column values (Discussion #2422)

[Hidde Wieringa]

Hello,

I am playing around with the experimental discrete isolation features of Osm2pgsql. Following the documentation in https://osm2pgsql.org/doc/manual.html#strategy-discrete-isolation and the blogpost https://blog.jochentopf.com/2022-12-19-selecting-settlements-to-display.html.

The goal is similar to the blog post, to improve the rendering of worldwide train stations on the map, using a calculated measure of importance stored in a database column. Some work in progress is in https://github.com/hiddewie/OpenRailwayMap-vector/pull/633.

In the original blog post is the sentence

> For the map above I used the formula "discr_iso_rank < (3.5 ^ @zoom_level) * 10 and importance_rank < (10 ^ @zoom_level)" to decide which places to show and which not to show. Of course, that’s only an example and it has to be tuned for different types of maps etc.

I would like to understand the exact meaning of the three columns `discr_iso`, `irank` and `dirank` better, in order to tune the values in the SQL queries. Can you elaborate on the exact meaning of the columns, the (expected) value ranges, and what high and low values mean, and how to interpret the values in the columns together?

Thanks in advance.

-- 
Reply to this email directly or view it on GitHub:
https://github.com/osm2pgsql-dev/osm2pgsql/discussions/2422
You are receiving this because you are subscribed to this thread.

Message ID: <osm2pgsql-dev/osm2pgsql/repo-discussions/2422 at github.com>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openstreetmap.org/pipermail/tile-serving/attachments/20251025/ef616701/attachment.htm>