From 32c3b6844d04601a2c53f375a0c68cc962ee88b4 Mon Sep 17 00:00:00 2001
From: tomrink <rink@ssec.wisc.edu>
Date: Sun, 14 Feb 2021 21:57:25 -0600
Subject: [PATCH] add inverse transforms
---
modules/util/geos_nav.py | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)
diff --git a/modules/util/geos_nav.py b/modules/util/geos_nav.py
index a7217e8f..58e8dfa6 100644
--- a/modules/util/geos_nav.py
+++ b/modules/util/geos_nav.py
@@ -211,6 +211,31 @@ class GEOSNavigation:
return geographic_lon, geographic_lat
+ def sat_to_earth(self, x, y):
+ if self.scan_geom == 'GOES':
+ x, y = goes_to_geos(x, y)
+
+ c1 = (h * np.cos(x) * np.cos(y)) * (h * np.cos(x) * np.cos(y))
+ c2 = (np.cos(y) * np.cos(y) + fp * np.sin(y) * np.sin(y)) * d
+
+ if c1 < c2:
+ return np.nan, np.nan
+
+ s_d = np.sqrt(c1 - c2)
+ s_n = (h * np.cos(x) * np.cos(y) - s_d) / (np.cos(y) * np.cos(y) + fp * np.sin(y) * np.sin(y))
+ s_1 = h - s_n * np.cos(x) * np.cos(y)
+ s_2 = s_n * np.sin(x) * np.cos(y)
+ s_3 = s_n * np.sin(y)
+ s_xy = np.sqrt(s_1 * s_1 + s_2 * s_2)
+
+ geographic_lon = np.arctan(s_2 / s_1) + self.sub_lon
+ geographic_lat = np.arctan(fp * (s_3 / s_xy))
+
+ geographic_lon *= RAD_TO_DEG
+ geographic_lat *= RAD_TO_DEG
+
+ return geographic_lon, geographic_lat
+
# def compute_scale_offset(lon_a, lat_a, col_a, line_a, lon_b, lat_b, col_b, line_b):
# lamda_a, theta_a = earth_to_sat(lon_a, lat_a)
# lamda_b, theta_b = earth_to_sat(lon_b, lat_b)
--
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