PIL images

tkrajina · tkrajina · commit a2da838a9b16 · 2013-05-30T06:19:29.000+02:00
diff --git a/README.md b/README.md
@@ -10,6 +10,16 @@ See: [http://www2.jpl.nasa.gov/srtm/](http://www2.jpl.nasa.gov/srtm/).
     >>> elevation_data = srtm.get_data()
     >>> print 'CGN Airport elevation (meters):', elevation_data.get_elevation(50.8682, 7.1377)
 
+You can create elevation images with:
+
+    import srtm
+    geo_elevation_data = srtm.get_data()
+    image = geo_elevation_data.get_image((500, 500), (45, 46), (13, 14), 300)
+    # the image s a standard PIL object, you can save or show it:
+    image.show()
+
+image.show()
+
 ## gpxelevations
 
 **TODO**
diff --git a/srtm/data.py b/srtm/data.py
@@ -28,8 +28,8 @@
 import zipfile as mod_zipfile
 import cStringIO as mod_cstringio
 
-
-import retriever as mod_retriever
+from . import utils as mod_utils
+from . import retriever as mod_retriever
 
 class GeoElevationData:
     """
@@ -129,7 +129,6 @@ def retrieve_or_load_file_data(self, file_name):
 
     def get_file_name(self, latitude, longitude):
         # Decide the file name:
-
         if latitude >= 0:
             north_south = 'N'
         else:
@@ -149,6 +148,52 @@ def get_file_name(self, latitude, longitude):
 
         return file_name
 
+    def get_image(self, size, latitude_interval, longitude_interval, max_elevation, 
+                  unknown_color = (255, 255, 255, 255), zero_color = (0, 0, 255, 255),
+                  min_color = (0, 0, 0, 255), max_color = (0, 255, 0, 255)):
+        """
+        Returns a PIL image.
+        """
+        import Image as mod_image
+        import ImageDraw as mod_imagedraw
+
+        if not size or len(size) != 2:
+            raise Exception('Invalid size %s' % size)
+        if not latitude_interval or len(latitude_interval) != 2:
+            raise Exception('Invalid latitude interval %s' % latitude_interval)
+        if not longitude_interval or len(longitude_interval) != 2:
+            raise Exception('Invalid longitude interval %s' % longitude_interval)
+
+        width, height = size
+        width, height = int(width), int(height)
+
+        latitude_from,  latitude_to  = latitude_interval
+        longitude_from, longitude_to = longitude_interval
+
+        image = mod_image.new('RGBA', (width, height),
+                              (255, 255, 255, 255))
+        draw = mod_imagedraw.Draw(image)
+
+        for row in range(height):
+            for column in range(width):
+                latitude  = latitude_from  + float(row) / height * (latitude_to  - latitude_from)
+                longitude = longitude_from + float(column) / height * (longitude_to - longitude_from)
+                elevation = self.get_elevation(latitude, longitude)
+
+                if elevation == None:
+                    color = unknown_color
+                else:
+                    elevation_coef = elevation / float(max_elevation)
+                    if elevation_coef < 0: elevation_coef = 0
+                    if elevation_coef > 1: elevation_coef = 1
+                    color = mod_utils.get_color_between(min_color, max_color, elevation_coef)
+                    if elevation <= 0:
+                        color = zero_color
+
+                draw.point((column, height - row), color)
+
+        return image
+
 class GeoElevationFile:
     """ Contains data from a single Shuttle elevation file. """
 
diff --git a/srtm/utils.py b/srtm/utils.py
@@ -0,0 +1,25 @@
+# -*- coding: utf-8 -*-
+
+# Copyright 2013 Tomo Krajina
+#
+# 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.
+
+def get_color_between(color1, color2, i):
+    """ i is a number between 0 and 1, if 0 then color1, if 1 color2, ... """
+    if i <= 0:
+        return color1
+    if i >= 1:
+        return color2
+    return (int(color1[0] + (color2[0] - color1[0]) * i),
+            int(color1[1] + (color2[1] - color1[1]) * i),
+            int(color1[2] + (color2[2] - color1[2]) * i))
diff --git a/test_srtm_file_to_image.py b/test_srtm_file_to_image.py
@@ -1,56 +1,16 @@
 # -*- coding: utf-8 -*-
 
+import logging as mod_logging
 import Image as mod_image
 import ImageDraw as mod_imagedraw
-import srtm as mod_srtm
-
-def get_color_between(color1, color2, i):
-    """ i is a number between 0 and 1, if 0 then color1, if 1 color2, ... """
-    if i <= 0:
-        return color1
-    if i >= 1:
-        return color2
-    return (int(color1[0] + (color2[0] - color1[0]) * i),
-            int(color1[1] + (color2[1] - color1[1]) * i),
-            int(color1[2] + (color2[2] - color1[2]) * i))
 
-UNKNOWN_COLOR = (255, 255, 255, 255)
-ZERO_COLOR    = (0  , 0  , 255, 255)
-MIN_COLOR     = (0  , 0  , 0  , 255)
-MAX_COLOR     = (0  , 255, 0  , 255)
-
-width, height = 300, 300
-max_elevation = 300
+import srtm as mod_srtm
 
-start_latitude, start_longitude = 45.0, 13.0
-# Zašto ovo pukne?
-#start_latitude, start_longitude = 43.0, 14.0
+mod_logging.basicConfig(level=mod_logging.DEBUG,
+                        format='%(asctime)s %(name)-12s %(levelname)-8s %(message)s')
 
 geo_elevation_data = mod_srtm.get_data()
-geo_file = geo_elevation_data.get_file(start_latitude, start_longitude)
-
-side = geo_file.square_side
-
-image = mod_image.new('RGBA', (side, side),
-                      (255, 255, 255, 255))
-draw = mod_imagedraw.Draw(image)
-
-for row in range(side):
-    if row % 100 == 0:
-        print 'row=%s' % row
-    for column in range(side):
-        elevation = geo_file.get_elevation_from_row_and_column(row, column)
-
-        if elevation == None:
-            color = UNKNOWN_COLOR
-        else:
-            elevation_coef = elevation / float(max_elevation)
-            if elevation_coef < 0: elevation_coef = 0
-            if elevation_coef > 1: elevation_coef = 1
-            color = get_color_between(MIN_COLOR, MAX_COLOR, elevation_coef)
-            if elevation <= 0:
-                color = ZERO_COLOR
 
-        draw.point((column, row), color)
+image = geo_elevation_data.get_image((500, 500), (20, 30), (-80, -70), 300)
 
 image.show()
