Talk:Polar Regions Rendering Issues

Base for zoom level differences

Although the average based on population may be at 30 degrees, this is not true for the stylesheet developers, who are generally in the 45-55 range. I'm going to go ahead and restore the 51 numbers.Pnorman (talk) 21:13, 18 June 2014 (UTC)

As i have written in the edit summary 51 degrees is a higher latitude than about 90 percent of the world population. Given that OSM is an international project trying to serve people from anywhere in the world equally i can only hope that the stylesheet developers you are talking about are not so self centered that they think designing the style primarily for this latitude is a good idea.

Unless you seriously think the standard map style should be optimized for 51 degrees latitude i would suggest your revert your revert. Because even if this has been an aim in the past maintaining this as a target for the future sends a very wrong message. --Imagico (talk) 22:23, 18 June 2014 (UTC)

I'm not suggesting optimization around any value. We don't design targeting **any** latitude. I'm saying that if you're going to compare zoom factors, you should do it around the average location of stylesheet authors or where they typically look at.

We're normally looking at something in the 45-55 range, not in the 0-30 range. The farthest south I have loaded in my test database is about 48 degrees. Pnorman (talk) 00:56, 24 June 2014 (UTC)

So you are saying style design does not target any particular latitude range but you and other style sheet developers are looking only at the 45-55 deg range when doing style design. I have troubles understanding this and likely i am not the only one.

Be that as it may - the way you modified the table clearly conveys the message that ~51 degrees is the target latitude of style sheet design.

The latitudes 0 and 30 degrees do not represent a range to target - 0 is the base latitude of the map projection where the projection units equal real world units. This is defined by the map projection (changeable through the proj4 +k/+k_0 parameter) and does not imply any preference for map design. 30 degrees is as explained about the world population average. You could reasonably add a third latitude that would minimize the average scale discrepancy for the viewers which would likely be around 35 degrees. This range (~30-35 degrees) would be the logical target range. There however is no way to motivate a base latitude of 51 degrees other than a subjective bias towards certain areas.

Aiming for a map style agnostic to the projected map scale variation is a great idea, with the currently employed tools this is however quite difficult to pursue.

As a general side note i would suggest to anyone doing map style development for global application to test on a wide range of areas around the globe - not only with regards to latitude but also for different general geographical settings. --Imagico (talk) 13:34, 25 June 2014 (UTC)

Alternative views

I came to this page looking for information about how OSM handles high latitudes - and I'm a bit confused. Surely, given the way that OSM works, there is no point in trying to un-optimise a map style which is, as suggested, optimised for temperate regions in order to make it render polar regions differently. The polar regions aren't going to be just sub-optimal on a web-mercator projection - they are going to be substantially wrong (in normal senses of the word). Rather than trying to fix a rendering designed for temperate regions it is surely necessary that the OSM community work to provide different maps which are optimised for those regions further north/south. Or am I missing something? Rostranimin (talk) 16:43, 10 November 2016 (UTC)

The central problem of almost all OSM based maps is the implicit assumption that the nominal map scale (ratio of pixels to map units) is the same as the real map scale (ratio of pixels to ground units) everywhere in the map - or a constant fraction of it. This assumption - how widespread it may be - is however not strictly required to render a map. So the idea to design maps based on real local scale is not something that should be dismissed sweepingly although usual tools do not really support this very well. And doing so would benefit both high and low latitude areas. Things like starting to display labels based on local scale rather than zoom level are quite feasible.

The discussion of thematic points mentioned on this page is rather outdated by the way. Many of the issues mentioned have changed in the meantime.--Imagico (talk) 23:05, 10 November 2016 (UTC)

I should be clear - I'm not challenging any assertion that there's a problem with the use of most standard tools in the polar regions - just the proposed solution I read here (changing the rendering of the existing tools & maps). We have established tools which are optimised in a way that doesn't work for polar regions - that's historically how maps work - they are always designed for a particular viewpoint (scale, projection, etc etc). We can't get away from this - but we CAN presumably use OSM in a way that provides different tools and maps which are optimised for different latitudes. Rostranimin (talk) 14:21, 13 November 2016 (UTC)