Alex-7 has commented on the following diary entries

Post When Comment
My new multilingual web application "Travel Info Pack" to view hotels, museums, supermarkets, cafes, etc. on the map prominently about 2 months ago

Thank you for your comment. I implemented your suggestion. shop=convenience or any other key=value pairs in the input fields will be saved for further usage.

Tool for measuring elevation above sea level on the OSM map 3 months ago

Adriano, and if I use both the barometric altimeter and a GPS/GLONASS altimeter? And on the day of the actual measurement I calibrate the barometric altimeter at the point with the known elevation?

A digital barometric altimeter is not expensive, about 50 USD. I plan to buy one.

I understand what you mean. A low quality GPS altimeter can have an error of about 50 meters. On my new smartphone, however, I have got a quality receiver. I went to the lake with the known elevation of 372 meters and the altimeter shows 373 - 375 meters when I stand near the lake consistently.

I do not suggest adding elevation on the OSM map haphazardly. But in places, where it makes sense. For example, an elevation of a remote mountain lake, or elevation in an area which is below sea level. As in my example above of New Orleans.

By the way, in some cities there are a lot of ele=* tags, For example, Zurich, Geneva, Stockholm, etc. And I did not add any ele=* tags in these cities, local mappers did. I just wrote a application which allows to view this data. And in some cases this data is of better quality, as in New Orleans.

Tool for measuring elevation above sea level on the OSM map 3 months ago

I do not have enough knowledge to answer your question. However I can tell that the local elevation data in some cases is of a better quality than the data from the global sources.

For example, if you check the elevations with this Google Map tool for the same area of New Orleans as in my post above you will see that it is always 0 meters, but in fact some places are below sea level.

And the local mappers are well aware of it. They know it only too well.

Tool for measuring elevation above sea level on the OSM map 3 months ago

This work was already done in New Orleans, Louisiana:

and in New York City:

It is immediately visible that these areas are in the flooding risk zones. And I cannot see it neither on the OSM map, not on Google map. At the same time floodings cause billions in danages.

Tool for measuring elevation above sea level on the OSM map 3 months ago

Some places in this area in the city of Odessa is about 1 meter below sea level, and this part of the city is prone to floods. I cannot see it even on the cycle map layer:

Next time, when I visit this city I may add some ele=* tags to prominent objects and it will be well visible with a single click. I know little about Papua New Guinea, I did not visit it yet, but in Odessa the floods cause terrible problems in this district, and such data could be helpful for understanding the issue.

The question is if my GPS altimeter will measure the elevations precisely enough, but if we do not use the altimeters the producers will not have an incentive to improve them. Besides, I can measure the elevation near the sea at the beach to calibrate the altimeter, and then cycle to the area for the actual measurements.

Tool for measuring elevation above sea level on the OSM map 3 months ago

I agree that it is not the best way to build a comprehensive elevation model.

However, with this tool I discovered already that there is the ele=* tag for the lake Lac Tanay, but not for the nearby lake Lac de Lovenex:

There is the elevation data in its Wikipedia article: and at its Wikidata item. But not in the OSM.

Next time when I go to this lake, I will go to the open space near the lake and measure the elevation with the GPS altimeter and add the ele=* t the OSM.

It makes sense to stay away from high walls which can reflect the GPS signal and cause interference by this.

Tool for measuring elevation above sea level on the OSM map 3 months ago

I agree that there are other ways to obtain elevation data. However in some places, for example Zurich or Geneva, even public transport stops have got the ele=* tag.

It is kind of DIY approach. Besides, the number of GPS satellites is increasing, the GPS receivers also become better. I think if not now, then in the near future the GPS altimeters could become precise enough.

Improving interaction between OSM and academic communities 6 months ago

It is an interesting initiative. There are serious unsolved problems in the GIS domain.

For example, making the OSM map addressable while billions of people do not have addresses because their streets do not have names at all (and will never have).

There were several attempts to solve this problem but we are not there yet. Perhaps a talented scientist is needed to solve it; someone like a mathematician Grigori Perelman. However, such a scientist should be aware of the problem existence in the first place.

Or building an universal up-to-date quality 3D map. The low altitude oblique aerial photography technology is developing very fast and is getting affordable but it is barely used in the OSM. We keep working with satellite imagery which sometimes is quite outdated.

So it's high time for new brave scientific ideas.

Describing Wikidata items with OpenStreetMap tags 12 months ago

It is very interesting. I did not know it. Thank you! From now on I will add OSM tag to Wikidata items where applicable.

Mapping in the least populated area in Germany about 2 years ago


There are quite a lot of German Wikipedia articles with geolocations around Prenzlau. You can see them with this tool:

At the same time not so many OSM tags wikipedia=de:, wikimedia_commons=Category:, wikimedia_commons=File:, wikidata=

There is a link to a Wikipedia or a Wikimedia resource at the marker. And if there is no photo in a Wikipedia article, it is possible to add one.

For example, I usually add an OSM tag, and also make a ground and an aerial image for an article. Here are some examples:

I wrote this tool o locate Wikipedia and Wikimedia resources for planning mapping and Wikipedia photogrpahy expeditions. It is a way to promote tourism in a region.

mfG A.

Geolocations of Wikipedia articles on the OSM map about 2 years ago

Search for geolocations of wikipedia, wikimedia_commons, wikidata OSM tags assigned either to nodes, areas, or ways is implemented.

Geolocations of Wikipedia articles on the OSM map about 2 years ago

k1wi, it is a good idea. Thank you. I've implemented already the display of Wikipedia articles geolocations by the wikipedia and wikimedia_commons tag assigned to a node in the same web-application.

It is a bit more complicated to display a geolocation when the wikipedia tag is assigned to an area or a way. It will try to implement it later.

Geolocations of Wikipedia articles on the OSM map about 2 years ago

This application uses the Wikipedia API. Actually it is just about 20 lines of code.

I use it to plan expeditions to make ground and aerial photos for Wikipedia articles.

There are other web-applications to find Wikipedia articles geolocations on other maps, but I wanted a clean interface, with the OSM map on the whole screen.

The addressable map of Geneva, Switzerland, project almost 5 years ago

Thank you! I improved wording as you suggested.