Question

我是gdal的新手。我正在尝试计算NDVI。但我有一些问题，所以我尝试做一些简单的测试，但是 “dataset.GetRasterBand（1）.WriteRaster（...）”不起作用，这导致空图像

我的代码是：

 #A function to create the output image
 def createOutputImage(self, outFilename, rb_ds):
    # Define the image driver to be used 
    # This defines the output file format TIF
    driver = gdal.GetDriverByName( "Gtiff" )

    # Check that this driver can create a new file.
    metadata = driver.GetMetadata()
    if metadata.has_key(gdal.DCAP_CREATE) and metadata[gdal.DCAP_CREATE] == 'YES':
        print 'Driver GTiff supports Create() method.'
    else:
        print 'Driver GTIFF does not support Create()'
        sys.exit(-1)

    # Get the spatial information from the input file
    geoTransform = rb_ds.GetGeoTransform()
    geoProjection = rb_ds.GetProjection()
    # Create an output file of the same size as the inputted 
    # image, but with only 1 output image band.
    newDataset = driver.Create( outFilename, rb_ds.RasterXSize, \
                                rb_ds.RasterYSize, 1, gdal.GDT_Float32)


    # Define the spatial information for the new image.

    newDataset.SetGeoTransform(geoTransform)
    newDataset.SetProjection(geoProjection)

    return newDataset


# The function which loops through the input image and
# calculates the output NDVI value to be outputted.    
def calcNDVI(self, red_band, NIR_band, outFilePath):
    # Open the red band dataset
    red_band_dataset = gdal.Open( red_band, gdal.GA_ReadOnly )
    nir_band_dataset = gdal.Open( NIR_band, gdal.GA_ReadOnly )

    # Check the dataset was successfully opened
    if (red_band_dataset is None) or (nir_band_dataset is None):
        print "The datasets could not openned"
        sys.exit(-1)

    # Create the output dataset
    outDataset = self.createOutputImage(outFilePath, red_band_dataset)
    # Check the datasets was successfully created.
    if outDataset is None:
        print 'Could not create output image'
        sys.exit(-1)

    # Load de two band
    red = red_band_dataset.GetRasterBand(1)

    for line in range(red.YSize):
        # read a line
        red_scanline = red.ReadRaster(0, line, red.XSize, 1, red.XSize, 1, gdal.GDT_Float32)

        outDataset.GetRasterBand(1).WriteRaster(0,line,red.XSize, 1, red_scanline, buf_xsize=red.XSize,buf_ysize=1, buf_type=gdal.GDT_Float32)


        del outputLine

    print "NDVI calculate correct"

我是从红色（图像）到outputDataset的行的复制行，但我有一个空图像

我正在使用此资源：http://learningzone.rspsoc.org.uk/index.php/Learning-Materials/Python-Scripting/9.4-Calculate-NDVI-using-GDAL

由于

Answer 1

如果没有提供输出（“NDVI计算正确”打印吗？），看起来这个程序在尝试del outputLine时会抛出错误，因为outputLine未声明。此崩溃将导致创建的图像写入一行，否则tiff将为空白。

WriteRaster不起作用

1 个答案: