[FWTools] Re: ReadRaster syntax

[Bryan Keith]

Hello,

I realize my original question may have not been very clear, but I 
solved my immediate problem.  The second row of a raster ought to be 
read like this:

band.ReadRaster(0,1,band.XSize,1,band.XSize,1,GDT_Float32)

not like I had guessed before.  So row n + 1 of a raster is read like this:

band.ReadRaster(0,n,band.XSize,2,band.XSize,1,GDT_Float32)

I'm still not totally clear what each parameter of the ReadRaster method 
is specifying.  If someone can point me to a help file, I'd appreciate 
it.  Thanks.

Bryan

Bryan Keith wrote:

> I start with this Python code:
>
> import gdal
> from gdalconst import *
> dataset = gdal.Open('ned_dem.asc',GA_ReadOnly)
> band = dataset.GetRasterBand(1)
>
> this line reads the first row in the raster:
>
> scanline = band.ReadRaster(0,0,band.XSize,1,band.XSize,1,GDT_Float32)
>
> this line reads the second row in the raster:
>
> scanline = band.ReadRaster(0,0,band.XSize,2,band.XSize,1,GDT_Float32)
>
> however, this line also reads the second row in the raster:
>
> scanline = band.ReadRaster(0,0,band.XSize,3,band.XSize,1,GDT_Float32)
>
> I'm guessing there's a problem with way I'm using the ReadRaster 
> method, but I haven't found any information on what each parameter is 
> supposed to be.  Thanks.
>
> Bryan
>
> Bryan Keith
> GIS Specialist
> Geomega, Inc.
> Boulder, CO, USA
>