That’s something the spanish community is aware of. These elements come from the Centro de Descargas del CNIG (IGN) , since they are rendered by the IGN raster map (it’s cartographic information). Actually, they’re altitude level marks.
The big issue here is the render, specifically, the carto-css or mapnik , which is doing nothing about it, since 2019:
abierto 02:17AM - 22 Mar 19 UTC
amenity-points
### Expected behavior
Prominent and isolated peaks should be shown at mid zoom … levels. It's common for large-scale maps to show the tallest mountain peak in a country, thus the most important mountain peaks should be shown as early as z8, when rivers are first shown.
Minor sub-peaks on the sides of larger mountains and insignifcant hills should not be shown until high-mid zoom levels (eg z14)
The names and elevations of important mountains should be rendered with priority. They should not be blocked by nearby minor peaks
### Actual behavior
All natural=peak features are shown from z11 without names or elevation, and the names are shown at z10 without clear prioritization of prominent peaks. In areas where many small peaks have been mapped, the map is full of peak symbols at z11
While the icons of taller peaks are prioritized, the name label of a tall mountain can be blocked by a minor subsidiary peak; eg the tiny "South Summit" of Mt Everest blocks display of the main peak's name label at several zoom levels.
### Possible Solutions
1) Use existing OSM tags, including name and elevation tags, to simply filter out less important peaks (i.e. those lacking names, elevation, or both).
- This can reduce the number of peaks in some areas, but many areas would still have too many at z11, and it would not be easy to filter for the 1% of most important peaks which could be shown at lower zoom levels.
2) Calculate an importance value for each peak based on the distance to the next higher peak
- This is similar to isolation, but would only look at the distance to other peaks (and saddles?) tagged with elevation
- Could be sufficient to show some very important peaks sooner, but would not work well in areas where elevation is not tagged for many peaks
3) Preprocess peaks from OSM database with a DEM (digital elevation model) to determine the isolation of each peak, and use this to help rank importance (along with name and elevation)
- Requires preprocessed data stored elsewhere or preprocessing along with a DEM at time of rendering
- Should allow a fairly robust importance rating for all peaks in the OSM database, including those that lack elevation tags
- Could be done frequently; daily basis
4) Preprocess peaks with a DEM to calculate prominence
- More complicated that finding isolation, because this requires creating a model of all ridge lines and saddles in addition to the location of peaks. However, prominence is considered a better importance rating for peaks by most mountaineers and climbers.
- Probably would need to be done infrequently; once per month, with results stored in a separate file (eg at osmdata.openstreetmap.de)
### Links and screenshots illustrating the problem
- The name and elevation of Mt Everest are blocked by the icon for South Peak (a tiny bump on the ridge with prominence of only 10 meters)
https://www.openstreetmap.org/#map=11/-6.9384/107.4223
- z11 East of Bandung in Java, many peaks are shown, but it isn't clear what is the tallest mountain, or where the main ridgeline is located.
https://www.openstreetmap.org/#map=11/48.9651/19.2563
- z11 Many peaks are shown at z11 near Ruzomberok in Slovakia, but most do not add clear information to the map
https://www.openstreetmap.org/#map=11/-3.2416/119.0774
- z11 in Sulawesi, Indonesia. Showing all of these peaks equally at z11 is not very helpful.
Zooming out to z10 shows no peaks. Mauna Kea in Hawaii is the tallest peak for 1000s of kilometers in all directions, and an elevation of 4205 meters, but is not shown at z10.
https://www.openstreetmap.org/node/2189450439#map=12/19.82069/-155.46804
You can test different renders to see how they deal with natural=peak (spoiler: better)
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