{ "id": 5431, "title": "Why are the LongitudeDegrees data points negative numbers?", "url": "/competitions/flight2-milestone/discussion/5431", "author_name": "", "post_date": "2013-08-17T21:51:10.347Z", "votes": null, "comment_count": 3, "views": 2074, "content": "

Also: are the specified waypoints in the data mandatory points imposed upon the flight, or are they just historical artifacts that just happened to be the waypoints that were chosen (important to know, as the entry submissions require us to designate waypoints). 

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Are user submissions free to contain as many ordinal "legs" of the flight as desired (presumably because our solvers for minimized total costs suggest such), or are the waypoints instead "nonnegotiable" i.e., imposed on each flight?

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Right now, I am presuming that the lat, long, altitude coordinates defining each waypoint are free to be chosen, and that we can make use of an arbitrary number of them, and thus specify as many ordinals for a flight as desired, but if I am wrong, it would be nice to know that this isn't the case.

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", "messages": [ { "id": "28877", "postDate": "08/17/2013 21:51:10", "content": "

Also: are the specified waypoints in the data mandatory points imposed upon the flight, or are they just historical artifacts that just happened to be the waypoints that were chosen (important to know, as the entry submissions require us to designate waypoints). 

\n

Are user submissions free to contain as many ordinal "legs" of the flight as desired (presumably because our solvers for minimized total costs suggest such), or are the waypoints instead "nonnegotiable" i.e., imposed on each flight?

\n

Right now, I am presuming that the lat, long, altitude coordinates defining each waypoint are free to be chosen, and that we can make use of an arbitrary number of them, and thus specify as many ordinals for a flight as desired, but if I am wrong, it would be nice to know that this isn't the case.

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", "rawMarkdown": "", "votes": null }, { "id": "28892", "postDate": "08/18/2013 11:34:32", "content": "

Negative latitude coordinate means south (positive north), and a negative longitude means west (positive east). So I guess data is focused to west side then?

", "rawMarkdown": "", "votes": null }, { "id": "28900", "postDate": "08/18/2013 16:47:42", "content": "

All flights westbound -  Is that what you mean? 

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That seems unlikely, but I am waiting to hear from someone from GE associated with this competition to settle what the positive/negative signs in the Lat/Long coords mean.

", "rawMarkdown": "", "votes": null }, { "id": "28902", "postDate": "08/18/2013 17:46:43", "content": "

In parallel with sfin's explanation above, the text & diagrams at the National Atlas say the following about how to interpret latitude & longitude when "directional designators" (like North, South, East, West) are omitted:

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[quote]When the directional designators are omitted, northern latitudes are given positive values and southern latitudes are given negative values.[/quote]

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Also: 

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[quote]There are 180 degrees of longitude to the east of the Prime Meridian; when the directional designator is omitted these longitudes are given positive values. There are also 180 degrees of longitude to the west of the Prime Meridian; when the directional designator is omitted these longitudes are given negative values. [/quote]

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So San Francisco, with lat/long of  (37.78° North, 122.41° West), is represented as (37.78, -122.41)

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Also the order, sign, and units of latitude & longitude are specified in international standards (e.g. see ISO 6709)

", "rawMarkdown": "", "votes": null } ], "comments": [ { "id": 28892, "author_name": "sfin2015", "author_url": "", "post_date": "08/18/2013 11:34:32", "content": "

Negative latitude coordinate means south (positive north), and a negative longitude means west (positive east). So I guess data is focused to west side then?

", "votes": null, "replies": [] }, { "id": 28900, "author_name": "booksiberia1", "author_url": "", "post_date": "08/18/2013 16:47:42", "content": "

All flights westbound -  Is that what you mean? 

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That seems unlikely, but I am waiting to hear from someone from GE associated with this competition to settle what the positive/negative signs in the Lat/Long coords mean.

", "votes": null, "replies": [] }, { "id": 28902, "author_name": "chefele", "author_url": "", "post_date": "08/18/2013 17:46:43", "content": "

In parallel with sfin's explanation above, the text & diagrams at the National Atlas say the following about how to interpret latitude & longitude when "directional designators" (like North, South, East, West) are omitted:

\n

[quote]When the directional designators are omitted, northern latitudes are given positive values and southern latitudes are given negative values.[/quote]

\n

Also: 

\n

[quote]There are 180 degrees of longitude to the east of the Prime Meridian; when the directional designator is omitted these longitudes are given positive values. There are also 180 degrees of longitude to the west of the Prime Meridian; when the directional designator is omitted these longitudes are given negative values. [/quote]

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So San Francisco, with lat/long of  (37.78° North, 122.41° West), is represented as (37.78, -122.41)

\n

Also the order, sign, and units of latitude & longitude are specified in international standards (e.g. see ISO 6709)

", "votes": null, "replies": [] } ], "raw_markdown_by_id": { "28877": "", "28892": "", "28900": "", "28902": "" }, "source": "meta" }