Changes between Version 14 and Version 15 of FAQRaster

Timestamp:

Oct 5, 2009, 11:16:01 AM (15 years ago)

Author:

Even Rouault

Comment:

Improve example thanks to Simon (Vsevolod) Ilyushchenko feedback

FAQRaster

@@ -30 +30 @@
 Another approach is to use one of the language bindings to GDAL to create a blank raster from scratch. The tricky part is understanding the !GeoTransform syntax.
 This python snippet shows how to read in a shapefile and output a tiff that matches the shapefile extents 
- * Note: you'll need to modify the `px` variable based on your desired resolution and raster dimensions
 
 {{{
 #!/usr/bin/env python
 
-from osgeo import gdal
-from osgeo import osr
-from osgeo import ogr
-import numpy
-
+try:
+    from osgeo import gdal
+    from osgeo import osr
+    from osgeo import ogr
+except:
+    import gdal
+    import osr
+    import ogr
+    
+# To be adjusted to your needs
 shp = 'test.shp'
 tiff = 'test.tif'
-px = .001
 tiff_width = 7850
 tiff_height = 3500
@@ -49 +52 @@
 vector = ogr.GetDriverByName('ESRI Shapefile')
 src_ds = vector.Open(shp)
-src_lyr = src_ds.GetLayerByIndex(index=0)
+src_lyr = src_ds.GetLayer(0)
 src_extent = src_lyr.GetExtent()
 
@@ -57 +60 @@
 
 # Create raster GeoTransform based on upper left corner and pixel resolution
-raster_transform = [src_extent[0], px, 0.0, src_extent[3], 0.0, -px]
+xres = (src_extent[1] - src_extent[0]) / tiff_width
+yres = (src_extent[3] - src_extent[2]) / tiff_height
+raster_transform = [src_extent[0], xres, 0.0, src_extent[3], 0.0, -yres]
 dst_ds.SetGeoTransform( raster_transform )
 
@@ -66 +71 @@
 
 # Create blank raster with fully opaque alpha band
-zeros = numpy.zeros( (tiff_height, tiff_width), numpy.uint8 )
-dst_ds.GetRasterBand(1).WriteArray( zeros )
-dst_ds.GetRasterBand(2).WriteArray( zeros )
-dst_ds.GetRasterBand(3).WriteArray( zeros )
-opaque = numpy.ones((tiff_height,tiff_width), numpy.uint8 )*255
-dst_ds.GetRasterBand(4).WriteArray( opaque )
-
+dst_ds.GetRasterBand(1).Fill(0)
+dst_ds.GetRasterBand(2).Fill(0)
+dst_ds.GetRasterBand(3).Fill(0)
+dst_ds.GetRasterBand(4).Fill(255)
 }}}