imagico has commented on the following diary entries

Post When Comment
Why I need OpenStreetMap 2 days ago

Regarding 'bitrot' (or in other words: the problem of outdated information) - it seems that typically OSM has a significant advantage over official mapping institutions in this field in many areas. But this is to a significant part because OSM is simply as a whole much younger than these institutions. In the future managing the transit from initial data acquisition (where the majority of edits add new data) to data maintenance (where the majority of edits update or correct existing data) is one of the big challenges of the future for OSM. We know this is possible - primarily from a few mostly urban areas where this is happening right now already but we also know that OSM currently is much better at initial data acquisition than at data maintenance which is likely in the future going to lead to significant volumes of essentially unmaintained data.

How are you "supposed" to map landuse? 3 days ago

A few things to consider:

  • Anyone can create a page like on the wiki - such pages are not in any way authoritative.
  • There is no authority in OSM that tells you how to map things. The tag pages (like are meant for documenting use of tags but do not always do so accurately.
  • In OSM you should only map what is observable on the ground. This contrasts strongly with typical landuse or landcover classification systems elsewhere which are based on assigning the least unlikely class to every point on the earth surface. You should not do that in OSM because that would devalue information on landuse that has been positively identified by mappers on the ground.
  • If you have an area you can positively identify as a certain landuse but there is no existing tag in OSM to describe it you should invent a new tag and document it.
  • If there is an area you can not verifiably attribute in a uniform way there is no need to map it at all.

So specifically: If you have an area where grain or other non-permanent crops are grown you can map it as landuse=farmland. If you have an area with residential buildings you can map it landuse=residential. If you do so diligently (i.e. making sure there are no larger areas that are not farmland or residential within the area you map) the areas you can uniformly map this way are usually fairly small. If they are larger it makes sense to map them in smaller parts (split at sensible lines) for easy maintainance.

AI With Satellite Images for OpenStreetMap 15 days ago

Basically, anything that is visible in a satellite image is now going to be able to be identifiable via software at the same level of accuracy as an “armchair” mapper.

Nothing could be further from the truth.

At the same time this statement is fairly demeaning for OSM mappers who - in the majority - map with a high level of competence and consideration. Comparing this to the crude mechanically trained monkey style algorithms commonly advertised as 'AI' these days demonstrates either a severe misunderstanding of the work of mappers in OSM or a similarily wrong understanding of how these algorithms work.

Religious belief in AI as the solution to any and all problems of mapping will not make these algorithms work any better or make them more useful for mapping in OSM.

About another OSMF board meeting about 1 month ago

You do state that you don't want to speculate, but then you do go on to speculate. You speculate "it is not clear if these are favours given in return for money". This is what led me to call you out for peddling conspiracy theories.

I think you are confusing speculation (in the sense of considering an unproven assumption to be true) with skepticism. Citing the paragraph in question as a whole:

Is delaying the announcement of a donation or inflating the importance of Missing Maps in OSM something that harms OSM? Maybe not. But because it is not clear if these are favours given in return for the money it certainly makes it less likely that people take things the OSMF board says at face value, i.e. it has a negative effect on credibility.

This argument does not hinge on the assumption that favours are given in return for the money (i.e. speculation), it is based on the uncertainty if they are (i.e. scepticism, not assuming something unproven to be true).

Another general remark regarding your style of communication in this discussion - i found your focus on specific words and use of language in contrast to focusing on the underlying reasoning and arguments which are independent of the specific words used (both in your replies to me and the analysis of Dale Kunce's remarks and context) problematic. Most people in the OSM community are not native English speakers and it is mostly a courtesy to you and other English speakers if they write in English. But there are many who feel deterred by the prospect of what they write being dissected into individual words and phrases which are then evaluated without giving consideration to the reasoning and arguments they are embedded in.

About another OSMF board meeting about 1 month ago


I think i made it very clear that i do not want to speculate on matters i have no insight into.

If you want to ignore my advise that the way things have been handled is not good for the credibility of the board and how this can be improved that is your choice. I think i explained my reasoning well enough so that anyone with an open mind would either be able to follow my reasoning or point out where my reasoning is flawed (so we could have a productive discussion like i had for example with Peda and Kate).

But i am not sure what you are trying to achieve with diverting into baseless and unrelated accusations. If that is an attempt to bully me into not speaking my mind in the future - that is not going to work.

About another OSMF board meeting about 1 month ago


I don't know the contractual details between the OSMF and the American Red Cross and i don't know what exactly is the chain of events that resulted in the timing of the announcement of the donation - nor why Martijn wrote the blog post in the form it was published. Therefore i don't want to speculate on these things. But the board should be aware that if they generally feel that they should aim to "give something back" for donations as long as it does not directly harm the goals of the OSMF people will look at actions of the board with that in mind and will wonder if things the board does are motivated by inherent interests of the OSM project and the community or of they are primarily in the interest of donors.

Is delaying the announcement of a donation or inflating the importance of Missing Maps in OSM something that harms OSM? Maybe not. But because it is not clear if these are favours given in return for the money it certainly makes it less likely that people take things the OSMF board says at face value, i.e. it has a negative effect on credibility.

Which i think brings us well back to the topic since credibility of the board was my main point regarding the subject in relation to which i mentioned the donation - i.e. the taking a stand agenda item.

Having clear policies on such matters, being transparent and avoiding organizational secrets as much as possible - and in this case: taking a clear stand on demeaning statements made in public by people with some connection to OSMF business are all ways to make it easier to maintain credibility.

About another OSMF board meeting about 1 month ago

Thanks for the comment and the additional perspective.

I assume you are referring to me pointing out that Peda is the only real hobby mapper with no professional relationship to OSM on the board. This is being said in the context of cultural diversity. With that in mind i think this is still a valid assessment because IMO what primarily defines my cultural background is not what i am doing right now but what i have done in the past.

When you are currently looking for work you are probably primarily looking for something where your past professional experience (which includes OSM) can be valuable - even if the work is not directly OSM related - just like Paul and Frederik will do work for customers that is not related to OSM. Peda however (who as you probably know started a new job last year) has no such OSM related professional background. This IMO gives him a unique perspective among the current board members.

But my point ultimately is not to argue who of the board members is the one that can most meaningfully speak for the OSM community - this would inappropriately reduce a highly multi-dimensional question to an arbitrary single dimension. I wanted to point out that the bandwidth of cultural backgrounds on the board is small so that even the most 'off-band' member (be that Peda or anyone else) is still very much mainstream compared to the bandwidth of backgrounds that exist in the OSM community.

And i am sure most of the current board members do at least occasionally perform recreational mapping.

About another OSMF board meeting about 1 month ago

I looked through the minutes and found the following face-to-face meetings:

  • 2010-01-23
  • 2010-12-11
  • 2011-06-11
  • 2011-11-04
  • 2015-02-16
  • 2016-05-28
  • 2016-09-25
  • 2017-05-20

I missed the 2015 one when writing this post but anyway there seems to be a distinct gap and therefore speaking of a regular feature does not seem quite right.

I think this also kind of relates to the matter of conservativism i mentioned in the end - if you do things out of tradition or of you do things because there are at the moment convincing arguments to do them.

About another OSMF board meeting about 1 month ago

Thanks Paul and Peda for the replies.

I want to comment further just on one thing Peda said:

But I think we owe it to the donor to only publish the news when the server is actually up and running to help them with their PR as well (i.e. give them something for their money).

This very fundamentally differs from my understanding of the role of the OSMF and the OSMF board and the function of donations. I don't want to pass judgement on this - it very well could be a cultural difference - but i have serious problems with understanding the moral framework behind the concept of donations cited above, i.e. donations resulting in the OSMF board having the obligation "to give something back". This clashes with my understanding of a "donation".

If i for example read the "alternative fact" of Missing Maps accounting for 10% of all OSM mapping contributions in the blog post - which seems odd because it is so clearly misleading (it is actually more like one percent) and the author of the blog post (Martijn) can be assumed to be able to check this quickly - i am now wondering if that is part of giving something back for the money. Although i personally would reject that idea i am obviously not the yardstick here, i just try to understand it.

With the above in mind i also noticed the blog post does not actually call it a donation, it calls it a "grant" - which is conceptually quite different. This would of course lead to the question what the contractual conditions of the grant are and in general to what extent the board can and should accept contractual obligations in exchange for money.

Given the overall volume of donations the OSMF now gets this might be a subject that deserves a somewhat broader discussion.

About another OSMF board meeting about 1 month ago

Note i put 'secret' in quotes.

My problem with that - as i have already indicated on osmf-talk i think - is not that this happened (everyone can make mistakes) but that the board presented it as if that was perfectly all right and just an insignificant delay and otherwise perfectly normal.

I would immediately stop "putting my finger into the wound" on this matter if the board

  • admitted that the way this was handled was wrong and counteracting the efforts in more transparency made otherwise.
  • put clear policy measures into place that will reliably prevent such thing from happening again (like for example a fixed requirement to publish any material contribution above EUR 5k within a month of it being made).
Motorway Junction Node Placement about 1 month ago

What might cause a bit of confusion here is that Daniel's example showed a tapered deceleration lane (see the first illustration) while the convention of including exit lanes in the main road lanes applies to parallel deceleration lanes (which is the only kind of lane we know in Germany). For the tapered deceleration lane there is no inclusion in the lanes of the main road as i understand things.

Motorway Junction Node Placement about 1 month ago

The neutral way to look at things like this is to consider which approach

  • provides the most information
  • is most intuitive and convenient for the mapper

The first point would call for approach two plus splitting the link into sections 'connected', 'theoretically separated' and 'physically separated'. Because approach three would not record information on the beginning of lane separation (which you would for example also need for precise routing) it would contain significantly less useful information.

The second point would in particular speak against the '45 degree angle' concept of your approach three which creates a purely abstract geometry element with no verifiability on the ground. You call this "balance between the needs of renderers and routers" (or in other words: combined tagging for the renderer and router) - i would call it codified mediocrity in both rendering and routing.

Have you looked at what approaches are actually most widely used in OSM - like some statistics on the angle between motorway and motorway_link at motorway_junction? You can bet that if you start fixing these to a 45 degree angle in a country where 2/3 of the junctions are mapped with a smaller angle you will rightfully get significant opposition to such edits. Looking at a few places around Europe it seems pretty clear that your 45 degree concept does not have much popularity.

Say hello to the giant Multipolygons 2 months ago

I just wanted to point out that the description of the historic development in OSM-Carto by kocio is not quite right. The problem with low zoom waterbody rendering has been discussed and fully analyzed many years ago - i linked to some parts of the discussion in the blog entry above - others are referenced from there. I also discussed the topic a bit more than year ago here from a somewhat different perspective (the rendering side) which was also referenced from the style development here.

The 'solution' now introduced is an approach that has been well known in rendering of OSM based maps and used in many maps, in particular ones without a mapper feedback mandate/function and commercial maps where cost efficiency is the primary goal for many years with similar low quality results. This approach has been rejected several times in the past in OSM-Carto (see in particular here and here).

I agree that the OSM-Carto issue tracker would be a better place for discussing the problem but a productive discussion would require all participants being fully aware of the previous state of discussion and a common understanding of the cartographic goals. At the moment i can see neither of these here. The problem is that while it is easy to recognize the issues with the current approach (as i pointed out in this diary) the cartographic and technical context is complicated and it is tempting to try ignoring parts of this context in the attempt to facilitate understanding. Ideas like "just stopped rendering water haze of sub-pixel size" are an example of such over-simplification. If you want to make it really simple it is best to accept that way_area filtering for filled polygon rendering just does not serve any positive goal, it is purely a method of reducing rendering costs at the expense of quality. This obviously is an over-simplification too but not a harmful one like the other way round.

Viewing OpenStreetMap tiles in GL 2 months ago

Grayscale rendering and other color processing with Leaflet - using canvas/CSS and not WebGL:

Viewing OpenStreetMap tiles in GL 2 months ago

You should however add that this is just the normal raster tiles from the tile servers rendered with WebGL. It is not a vector tiles based version of the standard style like what Rory/Geofabrik have showed some time ago:

Any post processing like for colors or rotation or other coordinate system transforms come with the usual problems of posterization/sampling artefacts etc.

Openlayers/Leaflet IIRC also offer b&w conversion, rotation etc.

Linear barriers 2 months ago

Your description of the latitude problem is correct - if you design your styling to appear 4m wide in Scotland (because the typical hedge is 4m wide) it will be rendered 8m wide at the equator.

You might not consider this to be a problem but you will always optimize for a certain latitude and in a way discriminate other latitudes with that by being less optimized there.

I see your point about the visual weight.

Linear barriers 2 months ago

The key to getting it working was to ensure that the width of lines used at high zooms mostly matched the real width of the feature on the map

The problem with that is that in Mercator it works reasonably well for a small area map like of Britain but it does not on a global map over a wider range of latitudes. There this kind of thing is much more complicated - see

Design wise i am not sure if a crossable barrier like a cattle grid being rendered much stronger than a non-crossable barrier like a fence or hedge is very intuitive. You can certainly get used to it but it still looks kind of strange.

Say hello to the giant Multipolygons 2 months ago

@Alan - I think that is a misunderstanding of the "One feature, one OSM element" rule in two separate ways.

First the riverbank polygons do not represent the river, they represent the water covered area of the river. This area can be split in mapping just like landuse mapping can be split. The river itself is represented by the linear ways with waterway=river and potentially a waterway relation collecting those ways.

Second i think "One feature, one OSM element" does not mean you need to merge all features that are part of a larger scale concepts into one OSM element (like all natural=wood areas that are part of the Amazon rain forest into one giant multipolygon). In case of a river mappers standing in Hamburg are mapping the Elbe locally as a way waterway=river, name=Elbe - like here:

Mappers in Lovosice will map their river locally with waterway=river, name=Labe:

This is not in violation of "One feature, one OSM element" because to the local mappers this is not the same feature obviously. The larger scale concept of a river as a global feature is represented as a waterway relation in addition but that is a concept separate from the river as a local feature.

All of this has nothing to do with the subject at hand: The problematic mapping incentives created by using way_area filtering on riverbank polygons in the standard style. Even if you want to interpret "One feature, one OSM element" differently and create thousands of new giant MPs extending in some cases across whole continents to represent the water covered areas of rivers as global concepts the right way to do that is to discuss this with the mapping community and achieve consensus on that matter, not to push this from a prominent map style for convenience of the map designers.

@nebulon42 - i understand your point and normally if it had just been a loss of quality in the map this is about i would not have said anything - hoping that even if those making the changes won't listen to me they will over time recognize the problems and either fix them or ask for and accept help to do better. But this is going to have a massive effect on mapping pushing mappers strongly in a certain direction so i think it is important to bring this up. And as you noticed i discussed this matter on many occasions in the map styling context so arguing the same point yet again in style development after my views on the matter have already been ignored there many times did not seem a very productive course of action.

I have considered resigning my position as maintainer but as long as OSM-Carto is prominently featured on the OSMF infrastructure i don't think this is the responsible thing to do. So i will continue providing critical feedback and provide alternative styling ideas to whoever will listen. I am grateful if there is a possibility to do that in style development but if not i will also do so in other places like here.

Say hello to the giant Multipolygons 2 months ago

Mapping for the renderer means mapping against established conventions to achieve a certain rendering result. Splitting riverbank polygons into small parts has always been documented practice and it universally used by mappers as you can now see in the standard style.

You probably did not notice my mapping tip to create a MP for thousands of lakes together was ironic. It is meant to illustrate that even if you are fine with the standard map style pushing mappers to a certain style of mapping against established practice and common sense this would still lead to completely ridiculous incentives in this case.

2017 Board Election Statistics 3 months ago

Just to avoid misunderstandings - the 2.9562 exhausted votes are from people who have had only 1 or 2 people on their ballot so after Heather was elected and David eliminated they did not have any vote left to make a difference. So if those who had Heather/David on 1/2 or the other way round or only one of them and an empty ballot otherwise they could have, if they had added Joost to the bottom of their list, made a difference in the final results.