1 files changed, 117 insertions, 0 deletions
diff --git a/src/projections/PJ_patterson.cpp b/src/projections/PJ_patterson.cpp
new file mode 100644
index 00000000..0d19414e
--- /dev/null
+++ b/src/projections/PJ_patterson.cpp
@@ -0,0 +1,117 @@
+/*
+ * Copyright (c) 2014 Bojan Savric
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/*
+ * The Patterson Cylindrical projection was designed by Tom Patterson, US National
+ * Park Service, in 2014, using Flex Projector. The polynomial equations for the
+ * projection were developed by Bojan Savric, Oregon State University, in
+ * collaboration with Tom Patterson and Bernhard Jenny, Oregon State University.
+ *
+ * Java reference algorithm implemented by Bojan Savric in Java Map Projection
+ * Library (a Java port of PROJ.4) in the file PattersonProjection.java.
+ *
+ * References:
+ *    Java Map Projection Library
+ *       https://github.com/OSUCartography/JMapProjLib
+ *
+ *    Patterson Cylindrical Projection
+ *       http://shadedrelief.com/patterson/
+ *
+ *    Patterson, T., Savric, B., and Jenny, B. (2015). Cartographic Perspectives
+ *       (No.78). Describes the projection design and characteristics, and
+ *       developing the equations.    doi:10.14714/CP78.1270
+ *       https://doi.org/10.14714/CP78.1270
+ *
+ * Port to PROJ.4 by Micah Cochran, 26 March 2016
+ */
+
+#define PJ_LIB__
+
+#include <math.h>
+
+#include "projects.h"
+
+PROJ_HEAD(patterson, "Patterson Cylindrical") "\n\tCyl";
+
+#define K1 1.0148
+#define K2 0.23185
+#define K3 -0.14499
+#define K4 0.02406
+#define C1 K1
+#define C2 (5.0 * K2)
+#define C3 (7.0 * K3)
+#define C4 (9.0 * K4)
+#define EPS11 1.0e-11
+#define MAX_Y 1.790857183
+/* Not sure at all of the appropriate number for MAX_ITER... */
+#define MAX_ITER 100
+
+
+static XY s_forward (LP lp, PJ *P) {           /* Spheroidal, forward */
+    XY xy = {0.0,0.0};
+    double phi2;
+    (void) P;
+
+    phi2 = lp.phi * lp.phi;
+    xy.x = lp.lam;
+    xy.y = lp.phi * (K1 + phi2 * phi2 * (K2 + phi2 * (K3 + K4 * phi2)));
+
+    return xy;
+}
+
+
+static LP s_inverse (XY xy, PJ *P) {           /* Spheroidal, inverse */
+    LP lp = {0.0,0.0};
+    double yc, tol, y2, f, fder;
+    int i;
+    (void) P;
+
+    yc = xy.y;
+
+    /* make sure y is inside valid range */
+    if (xy.y > MAX_Y) {
+        xy.y = MAX_Y;
+    } else if (xy.y < -MAX_Y) {
+        xy.y = -MAX_Y;
+    }
+
+    for (i = MAX_ITER; i ; --i) { /* Newton-Raphson */
+        y2 = yc * yc;
+        f = (yc * (K1 + y2 * y2 * (K2 + y2 * (K3 + K4 * y2)))) - xy.y;
+        fder = C1 + y2 * y2 * (C2 + y2 * (C3 + C4 * y2));
+        yc -= tol = f / fder;
+        if (fabs(tol) < EPS11) {
+            break;
+        }
+    }
+    if( i == 0 )
+        pj_ctx_set_errno( P->ctx, PJD_ERR_NON_CONVERGENT );
+    lp.phi = yc;
+
+    /* longitude */
+    lp.lam = xy.x;
+
+    return lp;
+}
+
+
+PJ *PROJECTION(patterson) {
+    P->es = 0.;
+    P->inv = s_inverse;
+    P->fwd = s_forward;
+
+    return P;
+}