[gdal-dev] Creating a new raster and adding data

[Henneke, Amanda M]

Thanks Frank for your help, I think I'm further, but still not quite
there.

The definition requires me to send the iBandMap as an array, I cannot
insert the index of the band I wish to write, because then I'm just
passing an integer.  So with that said, I decided to combine all my byte
arrays (buffers) of data into one array and call Write Raster as
follows:

byte[] buffers = new byte[(iHeight * iWidth) * 3];
r_buffer.CopyTo(buffers, 0);
g_buffer.CopyTo(buffers, r_buffer.Length);
b_buffer.CopyTo(buffers, r_buffer.Length * 2);

ds_new.WriteRaster(0, 0, iWidth, iHeight, buffers, iWidth, iHeight, 3,
iBandMap, 0, 0, 0);

But I'm still getting the same exception, so something else must not be
quite right.  I've tried playing around with the pixelSpace, lineSpace
and bandSpace parameters and still no success...any other ideas what I'm
still missing?

Thanks for any assistance!!

Amanda M. Henneke

-----Original Message-----
From: Frank Warmerdam [mailto:warmerdam at pobox.com] 
Sent: Friday, July 17, 2009 12:33 PM
To: Henneke, Amanda M
Cc: gdal-dev at lists.osgeo.org
Subject: Re: [gdal-dev] Creating a new raster and adding data

Henneke, Amanda M wrote:
...
> This is what I have so far...
> 
> Dataset ds = 
> Gdal.Open("F:\\Mat_Class\\Alaska\\new_tifs\\class_ak_sheet_8a.tif", 
> Access.GA_Update); Dataset ds_new = 
> drv.Create("F:\\Mat_Class\\Alaska\\new_tifs\\class_ak_sheet_8a_test.ti
> f", ds.RasterXSize, ds.RasterYSize, 5, DataType.GDT_Byte, new string[]

> { });
> 
> byte[] r_buffer = new byte[iWidth * iHeight]; byte[] g_buffer = new 
> byte[iWidth * iHeight]; byte[] b_buffer = new byte[iWidth * iHeight];
> 
> 
> <get/set values for r_buffer, g_buffer and b_buffer>
> 
> int[] iBandMap = { 1, 2, 3, 4, 5 };
> ds_new.WriteRaster(0, 0, iWidth, iHeight, r_buffer, iWidth, iHeight, 
> 1, iBandMap, 0, 0, 0); ds_new.WriteRaster(0, 0, iWidth, iHeight, 
> g_buffer, iWidth, iHeight, 2, iBandMap, 0, 0, 0); 
> ds_new.WriteRaster(0, 0, iWidth, iHeight, b_buffer, iWidth, iHeight, 
> 3, iBandMap, 0, 0, 0);

Amanda,

When I look in gdal/swig/include/csharp/gdal_csharp.i I see this
defintion:

public CPLErr WriteRaster(int xOff, int yOff, int xSize, int ySize,
      CSTYPE[] buffer, int buf_xSize, int buf_ySize,
      int bandCount, int[] bandMap, int pixelSpace, int lineSpace, int
bandSpace)

I think the problem is that you are passing 1, 2, and 3 as the bandCount
value when you are really only passing a buffer (ie. b_buffer) large
enough for one band.

I suspect you should be passing "1" for bandCount each time, but passing
different offets into iBandMap however that is most appopriately done in
C#.  In C/C++ I could do:

  int[] iBandMap = { 1, 2, 3, 4, 5 };
  ds_new.WriteRaster(0, 0, iWidth, iHeight, r_buffer, iWidth, iHeight,
                     1, &(iBandMap[0]), 0, 0, 0);
  ds_new.WriteRaster(0, 0, iWidth, iHeight, g_buffer, iWidth, iHeight,
                     1, &(iBandMap[1]), 0, 0, 0);
  ds_new.WriteRaster(0, 0, iWidth, iHeight, b_buffer, iWidth, iHeight,
                     1, &(iBandMap[2]), 0, 0, 0);


I'm not sure how this idiom translates into C#.

Good luck,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam,
warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent