Wikipedia:WikiProject Geographical coordinates/Linear
There are a number of ways in which linear referencing (coordinate referencing for linear features) can be added to Wikipedia. As yet, there is no single method which has achieved consensus.
The best method may depend on the type of feature, its length, and the number of significant points of interest along it (though such points need not be sufficiently notable as to warrant their own article).
What are linear features
[edit]Linear features include, but are not limited to:
- Tracks, trails, etc.
- Roads
- Railway lines
- Bridges
- Tunnels
- Canals
- Borders
- Rivers
- Valleys
- Mountain ranges
Options
[edit]Editors may give:
- One pair of coordinates, for the mid point
- One pair of coordinates, for the most significant point (e.g. the estuary or mouth of a river)
- Two pairs of coordinates, one for each end
- Three pairs of coordinates, combining the above
- Multiple coordinates, for points of interest
- No coordinates
Main coordinates
[edit]In any of the above cases, which involve more than one pair of coordinates, a single (or "main") pair may be used as the coordinates for the whole article (and for its inclusion in partner sites such as Google Maps).
A "main" coordinate may not be appropriate for very long features; the definition of "very long" in this context is yet to be determined.
Flexibility is needed in order to label a representative point. For example, a canal's "main" coordinates may be best given as a point where it is a body of water; a nearby location may be better than a midpoint occupied by a notable or atypical object such as a tunnel or causeway.
Solutions
[edit]- Whole article as table:
- Table in article (non-collapsible):
- Table in article (collapsible):
- Mouth of river:
- Both end points; plus middle as "main" coordinates:
- Each end:
Templates
[edit]These templates may be useful:
- {{coord}} - for each point's coordinates
- {{kml}} - maps of all coordinates; coordinates as KML download; etc.
Draft recommendations
[edit]feature | main coordinates 1 | further recommended coordinates 2 | optional additions3 | examples |
---|---|---|---|---|
bridge | midpoint5 | both ends | features crossed, support pillars | Astoria–Megler Bridge |
canal | midpoint5 | both ends | junctions, wharves, crossings, locks | |
unburied pipeline | midpoint5 | endpoints | pumping stations, junctions, major changes in direction | |
buried pipeline | one endpoint | other endpoint and midpoint5 | pumping stations, exposed sections | |
railway | midpoint5 | both ends | stations, former stations, junctions, significant bridges | |
river | estuary/mouth | source, major confluences | crossings, other confluences, boundaries crossed, weirs, major changes in direction, islands | Johnson Creek (Willamette River) |
road | midpoint5 | both ends | major towns visited, major junctions, major features crossed | M6 |
tunnel | one endpoint | other endpoint and midpoint5 | ventilation shafts | Robertson Tunnel |
valley | central point | both ends | watersheds, rivers, settlements, landmarks, features |
Notes:
- See above.
- For very short features (e.g. a small bridge) just the mid-point will suffice.
- For very long features, only major points of interest should be included.
- Route is a series of paths, as in a highway route. Or a long distance hiking trail, a series of individual trails which (usually) connect. To be unambiguous, the point must not be near any intersection
- "Midpoint" is not meant to be strictly the mathematical midpoint, but a representative point of the feature near its middle. If this should fall in a non-representative portion, the coordinate point chosen should be moved further toward one end. If the midpoint of a highway falls at an intersection with another highway, the coordinate chosen should be moved some distance from the intersection so that the other highway is not misinterpreted as the feature. Likewise, a highway portion which splits into two streets (as in an urban one way grid) should not be used as the selected point unless that is representative of the feature.
Precision
[edit]Coordinates for points on linear features should use a high level of precision, commensurate with features' small width, not great length, to ensure that the points are centred on, not merely near, the feature.
Out of scope
[edit]This guideline is not intended to cover:
- Polygons (i.e. country or county outlines) (e.g. Italy, Texas Coastal Bend)
- Lines of latitude or longitude.
- Forked, branched or other irregular features
- Non-linear collections of points of interest (e.g. "all cathedrals in England")
See also
[edit]Wikipedia:WikiProject U.S. Roads/Maps task force/Tutorial#Creating a KML file