[gdal-dev] How to use the GDALRasterize function. Spefically GDALRasterizeOptions.

[Even Rouault]

Sam,

> 
> I have a few questions with the GDALRasterize fuction.
> 
> 1) How do I set the GDALRasterizeOptions?
> I have tried:
> 
>     /// Create the list of options. Use the same as found on the command
> line gdal_rasterize utility
>     //  http://www.gdal.org/gdal_rasterize.html
>     char *options[] = {
>                             "-at", // All touched (all pixels touched by
> lines or polygons will be
>                                    //   updated, not just those whose center
> point is within the polygon)
>                             "-a_nodata", "-10", // Set the value to be used
> if there is no data
>                             "-tr", resolution_str, resolution_str, // Set
> the X and Y resolution (grid size)
>                             "-ot", dtype, // Set the output type (in this
> case we are using double)
>                             "-a", attribute,  // Set which attribute you
> want to use to determines the raster's value
>                             "-te", xMin, yMin, xMax, yMax, // Set the X,Y
> bounds of the raster (i.e. touched extent)
>                             "-q" // Quiet option
>                     };/

You need to add a final NULL pointer at the end of the options[] array, 
otherwise GDALRasterize() has no way to know where the array ends.

> 
> 
> 2) I am want to read the file I created with the GDALRasterize function
> immediately. When I try to do that by passing in a filename into the const
> char *pszDest (GD/ALRasterize(rasterfile.c_str(), NULL, ds_shp, Options,
> NULL);/), the get the no data value is what is read. After the program is
> finished, I can read the file normally. Therefore I do not think the file is
> closing until after the program has exited.

GDALRasterize() returns a dataset handle that you can potentially immediately 
use for reading its content with RasterIO().But at some point you explicitly 
need to GDALClose() it otherwise the dataset might not be completely 
serialized to disk

If you GDALOpen() this dataset before it has been closed, then you may read a 
partially flushed dataset.

Even

-- 
Spatialys - Geospatial professional services
http://www.spatialys.com