Opened 8 years ago

Closed 5 years ago

#3984 closed enhancement (wontfix)

[water] Use width tag for rendering rivers and possibly streets at higher zoom levels

Reported by: LM_1 Owned by: mapnik-team@…
Priority: major Milestone:
Component: mapnik Version:
Keywords: Cc:

Description

Correct rendering of wider rivers is supported by area features like riverbank, which is important for precision within urbanized area. Long rivers in nature (without riverbanks) are rendered unnaturally thin. If riverbanks are not there (way part of river lies within area riverbank) and the width tag is present render the river (canal/stream...) in appropriate size (width).

The same can apply for all highway types (even if this is less important because streets' widths are more consistent), but it would possibly save all the problems such as: http://trac.openstreetmap.org/ticket/3132, http://trac.openstreetmap.org/ticket/3053, http://trac.openstreetmap.org/ticket/2862, http://trac.openstreetmap.org/ticket/1492

This ticket is close to http://trac.openstreetmap.org/ticket/1721 and http://trac.openstreetmap.org/ticket/3076

Change History (4)

comment:1 Changed 8 years ago by Ldp

The width tag is visually hard to implement. What should render at the transition from sections with width tag and those without, or with different values?

All that could conceivably be done now is to make a sudden change in the width of the rendered line, which is aesthetically displeasing.

A major technical hurdle is the fact that the source data can be in different geographical projections, some in projected values, some in latlong values. Line widths are done in pixels. Somehow the geographical value would need to be translated to a pixel value.

In short, I don't see support for width=* tags in the foreseeable future.

comment:2 Changed 8 years ago by LM_1

Firstly, I believe that if it gets to be rendered, much more people would contribute the width (is there any feature that is rendered and not commonly mapped?). In the transition time, there could be "aesthetically displeasing" artefacts.

Sudden change is not the only option, it is imaginable, that the transition is rendered as a triangle going smoothly from the given width to zero between two nodes. Also if the width is changing, the different width could be tagged on two consecutive nodes and it would linearly change from one value to the other.

If you know where to render anything on the map, you must have a way to translate geographical (lat/long) value to pixels. And while transforming meters to pixels could be more complicated it is not impossible. After all, any routing software should be able to that. (There are much harder things done in the rendering)

If it is not a priority, I understand. It just seems to me that it is a feature that is currently missing the most...

comment:3 Changed 5 years ago by math1985

Summary: Use width tag for rendering rivers and possibly streets at higher zoom levels[water] Use width tag for rendering rivers and possibly streets at higher zoom levels

comment:4 Changed 5 years ago by math1985

Resolution: wontfix
Status: newclosed

This is difficult to accomplish. For example, what should we do where the width changes? Explicitly mapping the outline would be the best solution. I will close this as wontfix.

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