Merge pull request #360 from johntruckenbrodt/feature/ers_envisat

ERS and Envisat processing

Author: johntruckenbrodt

pyroSAR/ERS/mapping.py

@@ -321,10 +321,34 @@
 
 
 def get_angles_resolution(sensor, mode, swath_id, date):
-    string_new = ''
-    if mode == 'APP' and date > '20090528':
-        string_new = '-new'
+    """
+    Get acquisition characteristics not contained in the product metadata:
+    
+    - near range incidence angle
+    - far range incidence angle
+    - range resolution
+    - azimuth resolution
+    - near range noise equivalent sigma zero (NESZ)
+    - far range NESZ
+    
+    Parameters
+    ----------
+    sensor: {ERS1, ERS2, ASAR}
+        the satellite sensor
+    mode: {APP, APS, IMP, IMS, WSM}
+        the sensor acquisition mode
+    swath_id: {IS1, IS2, IS3, IS4, IS5, IS6, IS7, WS}
+        the sensor swath ID
+    date: str
+        the acquisition date formatted as YYYYmmdd/YYYYmmddTHHMMSS
+
+    Returns
+    -------
+    tuple[float]
+        the attributes listed above
+    """
+    suffix = '-new' if mode == 'APP' and date > '20090528' else ''
     data = ANGLES_RESOLUTION[sensor][mode][swath_id]
-    return (data[f'near{string_new}'], data[f'far{string_new}'],
-            data[f'range{string_new}'], data['azimuth'],
+    return (data[f'near{suffix}'], data[f'far{suffix}'],
+            data[f'range{suffix}'], data['azimuth'],
             data['nesz_near'], data['nesz_far'])

pyroSAR/ancillary.py

@@ -97,7 +97,8 @@ def groupbyTime(images, function, time):
 
 def multilook_factors(source_rg, source_az, target, geometry, incidence):
     """
-    compute multi-looking factors to approximate a square pixel with defined target ground range pixel spacing.
+    Compute multi-looking factors. A square pixel is approximated with
+    defined target ground range pixel spacing.
     
     Parameters
     ----------
@@ -126,15 +127,16 @@ def multilook_factors(source_rg, source_az, target, geometry, incidence):
     4 1
     """
     azlks = int(round(float(target) / source_az))
-    azlks = azlks if azlks > 0 else 1
+    azlks = max(1, azlks)
     if geometry == 'SLANT_RANGE':
         rlks = float(azlks) * source_az * sin(radians(incidence)) / source_rg
     elif geometry == 'GROUND_RANGE':
         rlks = float(azlks) * source_az / source_rg
     else:
-        raise ValueError("parameter 'geometry' must be either 'SLANT_RANGE' or 'GROUND_RANGE'")
+        raise ValueError("parameter 'geometry' must be either "
+                         "'SLANT_RANGE' or 'GROUND_RANGE'")
 
-    rlks = int(round(rlks))
+    rlks = max(1, int(round(rlks)))
     return rlks, azlks