[OSM-dev] Release openstreetmap-carto v2.25.0

Christoph Hormann chris_hormann at gmx.de
Thu Dec 11 12:10:24 UTC 2014

On Wednesday 10 December 2014, Matthijs Melissen wrote:
> Today, v2.25.0 of the openstreetmap-carto stylesheet has been
> released [...]

First of all these remarks don't have much to do with the changes of 
this release in particular, it is mostly that this has confirmed a 
number of observations i have made in the last months.

It seems to me that with the more active development of the style in the 
past year or so with frequent changes with high visual impact the mode 
of development of the style as it is currently practiced has reached a 
limit where it becomes very difficult to develop well composed changes 
to the style at all.

I am somewhat reluctant to bring up this problem since i think the more 
active development is a good thing in total and i don't want to 
badmouth this.

I have not done a precise statistical analysis but the time for a change 
from being designed to actually being deployed is fairly long, usually 
there are at least 1-2 releases in between, often several months.  This 
does not only mean changes need to be adapted to a changed codebase, it 
also means that the basis in terms of visual design is often changing 
significantly while a change is waiting to be merged.

As a result most changes which are deployed in recent releases are not 
really very well aimed.  They are meant to address certain issues but 
usually introduce at least as many new issues.  Other changes are then 
made later to address some of these with a similar result.  To some 
extent this is inevitable due to the complex interactions within the 
style but it is also largely a result of 'shooting at a moving target'.

I don't have a real solution for this problem but there are a number of 
things that IMO could much improve the situation:

(1) Systematic followups on the success and side effects of changes.  
The only case where i remember this happening is with the landcover 
labeling [1] but note that the majority of the issues pointed out there 
are not yet addressed now, two month later.  IMO development ressources 
should in most cases focus on bringing a change to a satisfying overall 
conclusion before working on new changes.  For most of the recent high 
impact changes this is not the case.

(2) Stricter queuing of changes for deployment.  The manner in which 
pull requests deemed ready for merging are selected for deployment 
seems quite random at least to the casual observer.  Some are merged 
within days, others take several months (the oldest one currently seems 
to be from July [2]) Followups on previous changes should probably be 
given priority.

(3) A test environment with worldwide data.  I know this is not a new 
suggestion and mostly a problem of ressources.  What would already 
help, especially for systematic followups on changes and would probably 
require much less ressources is a frozen tile cache that allows better 
before-after comparisons for changes already deployed.

[2] https://github.com/gravitystorm/openstreetmap-carto/pull/725

Christoph Hormann

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