I’ve been mapping for a bit in Portugal and am a bit astonished how well mapped polygons/areas are just blatantly deleted in Portugal.
Is this what the recommendations are for mapping in Portugal?
Example:
Pamela, entire residential area polygon just scrapped
Queluz-belas, caught a local mapper deleting all the residential polygons.
Luckily he put them back
This area, map was basically “finished” but the residential area had ofcourse to be deleted
The admins aren’t doing much about it, according to them players have time to correct/remove data but permanently deleting data is all standard from my experience.
I see that you’re basically talking about residential areas being deleted.
Residential areas applied to entire towns and cities is not correct data. Is a well debated issue and is seen by many (please, read the related wiki) as a mapping for the render, encompassing many other areas, like industry, religious, education, agricultural, and government areas, besides cemeteries, parks and other green areas.
Those polygons were probably deleted because of that. Please, don’t map entire urban areas as residential, because it’s not correct, it’s not verifiable and it doesn’t translate what exists on the ground.
Hey, not only at yours, here in the Canzano district and surrounding area seen them disappearing as snow for sun, residentials, tree groups, farm plots, address nodes and more. Used the JOSM ‘undelete’ function to get them back and sent a message to the ‘once in 3 years active mapper’. Actually had a msg back he would take it on for next time.
The use of Better-osm-org is a G-send… nicely lists out the deleted objects with ID codes and back they are… just parsed thru all the change sets by that mapper in reverse order to catch them all.
Was perusing the residential area wiki topics and came across a line saying that if there were inner areas to a residential zone, I’m thinking of school grounds, shopping centres and the like, they could be isolated with a multipolygon relation. That seems not to have aged well. Not seen or done that in long time, occasionally beginning mappers do that going by the letter of the wiki and that I leave alone, but for larger urban areas that develops into really unwieldy relations. For 360 fully inner areas can simply be mapped and the data consumers know to treat those areas as different to the surrounding. Think not so long ago that was confirmed by @Minh_Nguyen here on these forums, but as everything in OSM can change without notice, it may be changed view again.
PS And this line “It is strongly discouraged to glue landuse to road lines. Glued landuse makes the data much harder to work with.” done that myself in the me very early mapping days until I needed to maintain landcover changes… it cured me, but still see it being done. Fortunately, long as mapped as closed polygons glued to ways it’s extremely easy to split them off with the Ctrl+X function, when in a multipolygon relation it can turn into a serious chore. A ‘don’t glue area outlines to highways’ line should be plastered all over wiki’s touching on polygon and multipolygon mapping. Renders great, not a white pixel on the map, but beyond, please don’t.
Yes, it can be done with multipolygons, but as you mentioned, this would leave many relations in a big area creating many difficulties to edit and many headaches to other mappers. Residential areas should be mapped as other landuse areas, ie, just where they exist (neighbourhoods, living areas and small villages where almost all houses are residential) and not covering huge areas just to appear on the map.
About gluing areas to roads, this is an old problem that could be solved if editors warned mappers that this should be avoided. Unfortunately, iD (because it’s the most used) development is stalled and this is one of the many things that were not implemented.
Renderers will always draw smaller landuses after larger ones, and so smaller areas can be safely mapped on top of larger ones without the complication of multipolygons from the viewpoint of rendering. But in general data consumers won’t “know” how to handle “stacked” landuses, and so I would tend to use MPs for larger inner areas, so that data consumers will be able to correctly calculate e.g. retail vs. residential landuse areas.