Every node in DDD can contain metadata. Metadata is a free set of key=value pairs, which can be used freely to describe the element.
Metadata can also be used for filtering the objects to which operations apply, being a key piece of DDD generation pipelines.
Attributes starting by _ are considered private, and some of these are used internally by DDD.
These attributes are not exported with metadata when the output is saved.
OSM uses height as the "max height" at which a feature exists. For building and other features
which also have a min_height, the actual height is calculated as height - min_height.
Other objects, like roof:height, do instead acually contain the height of that part.
DDD uses "height" for actual object height, regardless of the "min_height" (called base_height
in DDD).
For instance, a fence on the top of a building may be tagged as "height=51" and "min_height=50" in OSM. In DDD the same fence would be described with "height=1" and "base_height=50".
svg:image:data svg:image:height svg:image:width
Used by the SVG exporter. When a node contains `svg:image:data`, a SVG Image element
is created in place of the node, using the given image.
ddd:elevation = geotiff | ddd:area:elevation
Defines which 3D elevation strategy will be used to position the object/vertices in 3D.
Values:
- geotiff
- water (s30_groups_ways)
- path (used by ways)
- (also seen 'max' in ddd:area:elevation)
ddd:area:height ddd:height
Defines area height (over base ground elevation).
Currently this is used for "raised" areas, those that have a kerb or an abrupt
transition of height, but interpretation may vary by area type.
ddd:item:elevation ddd:elevation _height_mapping
Defines which 3D elevation strategy will be used to position the object/vertices in 3D.
Values:
- terrain_geotiff_min_elevation_apply
- terrain_geotiff_elevation_apply
- building
ddd:elevation:base_ref
Values:
- container
ddd:height:base
Item vertical offset.
ddd:min_height osm:min_height + ddd:height ddd:item:height osm:height
Used for fences min_height and max_height. TODO: Normalize! but note Torre de Hercules fence uses min_height=50
ddd:building:elevation _terrain_geotiff_min_elevation_apply:elevation
Defines which 3D elevation strategy will be used to position the object/vertices in 3D.
(TODO: check, usage not confirmed)
ddd:building:elevation:min ddd:building:elevation:max
Stores min and max ground elevation values for a building footprint.
ddd:building:level:0:height
Defines the height of a building's base level (floor 0). This level is deemed
special as the footprint of the building will usually touch the ground at different
elevations, burying part of the building into the ground.
This level 0 height is floor 0 height plus the elevation difference of the footprint.
TODO (review)
osm:height
Used as max_height (note this is MAX height) of a building or building part.
ddd:roof:height osm:roof:height
Building roof part height, in meters.
ddd:extra_height ddd:height ddd:way:height osm:height
Used during way metadata processing. Represents the thickness of the road over
the ground terrain.
For historical reasons, this is obtained from osm:height if available, then managed
as ddd:way:height during the s30_ways phase, then finally copied to ddd:height
and ddd:extra_height.
TODO: Normalize and review usages!
_terrain_geotiff_min_elevation_apply:elevation _terrain_geotiff_max_elevation_apply:elevation
(Internal) Set by the terrain module when applying max or min elevation to an object.
_* Used internally? (not exported?) _last_extr? Extrusion info... etc?
osm:* OpenStreetMap schema metadata osm:item:* Item osm:way:* Way osm:area:* Area + layer + area/way raised vs base + base_height (osm, ddd...)
**
ddd:map:way:width ??
Properties understood by... (?)
ddd:* DDD metadata ddd:crop:* Cropping ddd:elevation:* Elevation applying ddd:align:* Align type ddd:area:raising? ?