sharpetronics/Map-Projections
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So many cones

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I fixed up American polyconic, and I'm kind of glad I have it, even though it's a terrible map projection whose only application is making gores and Cassini is better for that, anyway.
This commit is contained in:
Justin Kunimune 2019-10-15 22:41:17 -04:00
parent cf8d4ca4dc
commit 5cf6bcd6e2
2 changed files with 19 additions and 4 deletions
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5
src/apps/MapApplication.java
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@ -145,8 +145,9 @@ public abstract class MapApplication extends Application {
Pseudocylindrical.MOLLWEIDE, ArbitraryPseudocylindrical.NATURAL_EARTH,
ArbitraryPseudocylindrical.ROBINSON, Pseudocylindrical.SINUSOIDAL,
Tobler.TOBLER, Pseudocylindrical.WAGNER_II, Pseudocylindrical.WAGNER_V },
{ Lenticular.EISENLOHR, Gyorffy.E, Lenticular.HAMMER, Lenticular.LAGRANGE,
Lenticular.STREBE_95, Lenticular.VAN_DER_GRINTEN, Lenticular.WAGNER_VIII,
{ Lenticular.AITOFF, Lenticular.POLYCONIC, Lenticular.EISENLOHR, Gyorffy.E,
Lenticular.HAMMER, Lenticular.LAGRANGE, Lenticular.STREBE_95,
Lenticular.VAN_DER_GRINTEN, Lenticular.WAGNER_VIII,
WinkelTripel.WINKEL_TRIPEL },
{ Misc.BONNE, Snyder.GS50, Misc.GUYOU, Misc.HAMMER_RETROAZIMUTHAL,
Pseudocylindrical.LEMONS, Misc.PEIRCE_QUINCUNCIAL, Misc.T_SHIRT,

18
src/maps/Lenticular.java
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@ -286,7 +286,7 @@ public class Lenticular {
public static final Projection POLYCONIC = new Projection(
"American polyconic", "A map made for narrow strips of longitude that was really popular with the USGS for a while.",
2*Math.PI, 3.5, 0b1011, Type.OTHER, Property.EQUIDISTANT, 3) {
2*Math.PI, 4.81527, 0b1011, Type.OTHER, Property.EQUIDISTANT, 3) {
public double[] project(double lat, double lon) {
if (lat == 0)
@ -296,7 +296,21 @@ public class Lenticular {
}
public double[] inverse(double x, double y) {
return null;
if (y < 0) { // the math gets inconvenient in the Southern Hemisphere
double[] refl = inverse(x, -y);
return new double[] {-refl[0], refl[1]};
}
else if (y == 0)
return new double[] {0, x};
double logitLatGuess = Math.log(Math.hypot(x, y+Math.PI/2)/Math.hypot(x, y-Math.PI/2));
double lat = NumericalAnalysis.bisectionFind(
(ph)->(Math.pow(x, 2) + Math.pow(y - ph, 2) - 2*(y - ph)/Math.tan(ph)),
0, Math.PI/2*(Math.exp(logitLatGuess) - 1)/(Math.exp(logitLatGuess) + 1), // this guess is pretty complicated, but I'm proud of it
1e-4);
if (Double.isNaN(lat))
return null;
return new double[] { lat, Math.atan2(x, -(y - lat - 1/Math.tan(lat)))/Math.sin(lat) };
}
};