OSM usually doesn't contain the exact outline of a junction or intersection (except in very few cases where area:highway has been mapped) and most roads don't have a width set.
However you can try to estimate it by looking at the highway class (i.e. primary, secondary, tertiary...) and the number of lanes.
You cannot measure the area of a lines layer.
Convert your lines layer (building outlines) into polygons.
Try Vector>Geometry Tools>Lines to Polygons then reapply your $area expression on the output. The output might require some tweaking if the line nodes to not join together. If you have gaps in the output, try buffering it by 1m and dissolve the result, ...
There is ST_Node & ST_Polygonize, which should do what you need:
SELECT ST_Collect(<geom>) AS multi_geom
-- WHERE <condition>
-- GROUP BY <attribute>
You might want to use a filter and/or grouping attribute to put a limit on the ...
Here's an alternative to splitting the streets at their intersections and converting them into polygons. I don't know if this method is better, but I do think it's interesting to consider different ways of approaching a problem.
Basically, we create a large polygon, and use the streets to split up that polygon.
Create a large "background" polygon, eg ...
it seems like you need to create blocks based on street intersection? you can run the intersect tool in arcmap and set the output type as point. this will give you the points of each intersection.
however, by using streets to create polygons, you can set a buffer around the streets between 30-40ft and dissolve by name of street. This will give you ...
The query in your question looks for the road name. "I 55" and "I 270", however, are modeled in OSM using the ref tag because they aren't really names. You need to modify the query accordingly:
This won't return any results, though. The on/off ramps ...
What I did when I needed to sample the spectral profile of a web map layer was to right click the layer, export the Raw Data to GeoTiff, choose an appropriate extent, and set an appropriate resolution for the layer (it likely will not set a value other than 0, which will yield a failed export).
Then, you do you work off this rendered image. Not ideal, but ...
One possibility of doing this would be with the help of turf.js library.
When adding newly drawn polygon, algorithm for detecting and creating possible holes goes like this:
Convert newly created layer/polygon to GeoJSON and then to turf geometry.
Iterate through all existing layers/polygons.
Convert each layer/polygon to turf geometry and check if it ...
Convert creates so called "derived" objects, which have a slightly different behavior in this case. To get geometry details, you need to replace out; by out geom;, as well as using ::geometry = geometry() like you already did in your second example.
Query would then be:
You can either:
Use the Query Features Tool from the sidebar on the right (the arrow with the question mark, see element 11 at Browsing) and click on the outline of the lake. This will show you all nearby elements.
Log in with your OSM account and click on edit, this will open your favorite OSM editor for the current area.
Use the search box to search for ...