Timeline for Prior art on rhumb line and great ellipse areas?
Current License: CC BY-SA 3.0
10 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| May 1, 2015 at 14:18 | vote | accept | cffk | ||
| Nov 4, 2014 at 20:42 | answer | added | cffk | timeline score: 3 | |
| Nov 3, 2014 at 7:39 | comment | added | Martin F | Somewhat related question: gis.stackexchange.com/questions/41157/… | |
| Nov 3, 2014 at 2:14 | comment | added | cffk | Danielsen dx.doi.org/10.1179/003962689791474267 solved the problem where the edge is a geodesic in 1989 and that solution is employed by GeographicLib. Extending the technique to rhumb lines and great ellipses is straightforward enough (see the links in the question). | |
| Nov 2, 2014 at 23:13 | comment | added | mdsumner | Ok thanks, we are on the same page at least. I don't see a problem with this, it's a limitation in most systems that the "curve" must be stored as an approximation rather than be generated on the fly from a rhumb or gc rule. I am interested to see if there will be any answers. | |
| Nov 2, 2014 at 22:01 | comment | added | cffk | Consider measuring the area of an polygon where one side is a rhumb line running SE from 39N 120W to 35N 115.0107164W (part of the border between California and Nevada). This "line" becomes a curve in the Lambert equal-area cylindrical projection (and most other equal area projections). So you'll need to insert intermediate points on rhumb line to be able to represent the polygon accurately in an equal-area projection. So instead of doing one unit of work to calculate the area contribution of this edge, you'll have to do 630 units of work (assuming you need to insert one point per km). | |
| Nov 2, 2014 at 20:45 | comment | added | mdsumner | Equal area not angle. The extra vertices are not for calculating per se, just for representing the region in the right way. I don't get your overall task really, I don't see how it's any different to calculating area normally. | |
| Nov 2, 2014 at 13:15 | comment | added | cffk | @mdsumner, you're right that using an equal angle projection is the standard way to handle area calculations. However, the need to insert (a possibly large number of) intermediate vertices makes this method equivalent to "slicing the area into many strips". As a result, the calculation either slow or inaccurate or both. I'm interested in methods which don't have this limitation. | |
| Nov 2, 2014 at 1:16 | comment | added | mdsumner | Standard practice would be to do the calcs in an appropriately local equal area projection. Right? The only real issue is whether your shapes have sensible topology and/or sufficient vertices to represent whatever the thing is correctly when you transform, or draw it in that projection. (But this a constant concern that is basically a broken part of most/all GIS, and a key knowledge base item of the "expert-practitioner"). | |
| Nov 1, 2014 at 20:33 | history | asked | cffk | CC BY-SA 3.0 |