A property to describe a covered node, way or area, when the use of layers is inappropriate or further clarification is needed.
Used to denote that an object represented by a node, way or area is covered, where layering is inappropriate, or additional clarification is needed.
While layering is the conventional means of showing that one object is covered by another, layering, by wiki definition is to denote separate physical levels. There are numerous situations where layering is inappropriate, and can be misleading in the context of the subsystem being mapped. For example, when a building has a way passing through it, and both the way and the building are at ground level, layering the way at -1 or the building at 1, sets inappropriate physical relationships to other surrounding entities. A tag of "covered" on the entity can not only address this issue, but will also make routing more efficient in cases where, for example, a route to avoid the natural elements is desired, or a route to covered parking or to an area for sheltered entry or egress into a vehicle is desired.
In addition, layering of excavated areas such as underground parking garages and reservoirs only shows relative vertical position, and not whether there is a (concrete supported) ground covering over the area.
To be used to
A. denote that a highway, railway, pedestrian way or waterway passes under a building or other structure, where it is inappropriate to use layering as the differentiator between covered and uncovered. or where "covered" will more clearly define the condition.
B. denote that a power line, water main, water drain, etc., in a narrow trench, has a removable and replaceable covering, allowing for maintenance, and thus potentially allowing it to be traversed without a bridge.
C. denote an area such as an underground parking lot, a covered reservoir/cistern or even such things as an aquarium (e.g., Kelly Tarlton's, Auckland, NZ), when the covering is not a man-made structure that would allow layer differentiation.
When NOT to use:
- as a tunnel feature, since "covered=yes" is implied for tunnels.
- on a highway passing under a bridge, where the path of the under-passing highway may be accurately assumed.
- for entities that are buried in the earth or submerged in water. However, underground excavations, such as parking lots and reservoirs are appropriate.
Can be used along with layering in cases where it would assist in completely describing the relationship.
- http://www.fffw.org/Randy/Photos/covered_storm_drain.jpg Covered storm drain - Matsusaka, Japan
- Wikipedia:Snow shed
maxheight=* may also be associated with the covered way or area to indicate clearance.
Rendering would depend on the object being covered, but would, in general, "diminish" the uncovered rendering.
Rendering suggestions include
- parallel dashed lines with no color fill to denote a covered highway. - a lighter or different color to denote a covered pedestrian way. - a dashed line to indicate a covered waterway (blue) or power line (black).
One option would be to render the covering object (in the renderer's drawing sequence) as semitransparent. This would work in most situations, but might not be visually distinct for narrow lines, which might better be rendered as dashed, similar to in tunnels.
This tag potentially deprecates the following tags:
- man_made=reservoir_covered by man_made=reservoir + covered=yes
- misuse of tunnel=yes
- Questionable use of layering