[gdal-dev] empty Gtiff from Python

[Chris Yesson]

Tom,

I have just run your code exactly as you sent it (except for output
path), with python 2.5.2 ang gdal 1.8.1.  The ouput file appears in
order (gdalinfo output below).  The file opens and displays normally in
qgis trunk v 1.8.

- Chris

Gdalinfo output

Driver: GTiff/GeoTIFF
Files: output.tif
       output.tif.aux.xml
Size is 10, 10
Coordinate System is:
LOCAL_CS["arbitrary",
    UNIT["metre",1,
        AUTHORITY["EPSG","9001"]]]
Metadata:
  AREA_OR_POINT=Area
Image Structure Metadata:
  INTERLEAVE=BAND
Corner Coordinates:
Upper Left  (    0.0,    0.0)
Lower Left  (    0.0,   10.0)
Upper Right (   10.0,    0.0)
Lower Right (   10.0,   10.0)
Center      (    5.0,    5.0)
Band 1 Block=10x10 Type=Byte, ColorInterp=Gray
  Min=1.000 Max=1.000
  Minimum=1.000, Maximum=1.000, Mean=1.000, StdDev=0.000
  Metadata:
    STATISTICS_MINIMUM=1
    STATISTICS_MAXIMUM=1
    STATISTICS_MEAN=1
    STATISTICS_STDDEV=0

Date: Fri, 28 Oct 2011 10:23:04 +0200
From: Tom van der Putte <tom at vdputte.nl>
Subject: [gdal-dev] empty Gtiff from Python
To: <gdal-dev at lists.osgeo.org>
Message-ID: <4335.1319790184 at vdputte.nl>
Content-Type: text/plain; charset="utf-8"

Hi
List,
 I'm trying to save a numpy array to a GTiff, which should be quite
straightforward, considering all the examples available on the web.
However, I get an file that is not readable by Qgis, is regarded by
ArcMap to have only 0 and gdalinfo displays nothing on the values.
 I start with a ndarray, dtype = int32, shape = ( 10,10). It has
integer values between 1 and 10. The code is as follows:
 import numpy as np
 from osgeo import gdal
 from osgeo import osr
 #np array
 a = np.ones((10,10))
 #coord-system
 sr_str = 'LOCAL_CS["arbitrary"]'
 sr = osr.SpatialReference( sr_str )
 #driver
 driver = gdal.GetDriverByName("GTiff")
 #dataset
 ds = driver.Create("D:\temp\output.tif", 10, 10, 1, gdal.GDT_Byte)
 ds.SetProjection( sr_str )
 ds.SetGeoTransform((0, 1, 0,0, 0,1))
 #write and close
 ds.GetRasterBand(1).WriteArray(a)
 ds = None
 The corresponding gdalinfo is:
 *********
 Raster dataset parameters:
   Projection:
LOCAL_CS["arbitrary",UNIT["metre",1,AUTHORITY["EPSG","9001"]]]
   RasterCount: 1
   RasterSize (10,10)
 Using driver GeoTIFF
   Metadata:
     0:  AREA_OR_POINT=Area
   Image Structure Metadata:
     0:  INTERLEAVE=BAND
 Corner Coordinates:
   Upper Left (0, 0)
   Lower Left (0, 10)
   Upper Right (10, 0)
   Lower Right (10, 10)
   Center (5, 5)
 Coordinate System is:
 LOCAL_CS["arbitrary",
     UNIT["metre",1,
         AUTHORITY["EPSG","9001"]]]
 Band 1 :
    DataType: Byte
    ColorInterpretation: Gray
    Description:
    Size (10,10)
    BlockSize (10,10)
 *********
 I have tried both version 1.6.3 (I'm trying to make a Qgis plugin,
and thus restricted to 1.6.3) as well as 1.8.1. I have also tried ds =
driver.Create("D:\temp\output.tif", 10, 10, 1, gdal.GDT_Int32), but
that didn't make much difference.
 I tried to make a Surfer grid (GSBG), and this somewhat worked: it
gave a nice picture, but the values were off the charts.
 Any clues as to what I'm missing here? Cheers,
 Tom van der Putte
  
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