Executing GDALRasterize() function wtih options

Question

I am using GDAL 2.1.0, in both Windows and Linux environments.

I want to programmatically rasterize a shapefile in my C++ app.

gdal_rasterize

I can successfully execute the stand-alone gdal_rasterize app from the command line. For example, the following works to rasterize a shape file that contains areal features about farms.

gdal_rasterize  -a 'crop_id'  -l 'farms'  -init 0  -ts 1024 1024  -ot Byte  farms.shp  farms.tif

GDALRasterize()

The following is my attempt to perform the same rasterization within my C++ app.

GDALAllRegister();

...

//------------------------------
// Paths of the source and destination files, relative to current working directory.
string srcPath = "farms.shp";
string dstPath = "farms.tif";

//------------------------------
// Open the vector dataset.
unsigned int openFlags = GDAL_OF_VECTOR | GDAL_OF_READONLY; 
GDALDataset * pSrcDataset = static_cast<GDALDataset *>( GDALOpenEx(
  srcPath.c_str(), 
  openFlags,
  NULL, NULL, NULL ) );

// The one layer.
OGRLayer * pSrcLayer = pSrcDataset->GetLayer( 0 );

//------------------------------
// Rasterize options.
// TODO: Are these intended to be just like the command line arguments 
// I would use if executing gdal_rasterize?
// https://gdal.org/programs/gdal_rasterize.html
char ** argv = NULL;

// -a <attribute_name>
// An attribute field on the features to be used for a burn-in value.
argv = CSLSetNameValue( argv,  "-a", "crop_id" );

// -l <layer_name>
// The layer from the datasource that will be used for input features.
argv = CSLSetNameValue( argv,  "-l", pSrcLayer->GetName() );

// -init <value>
// Pre-initialize the output image bands with these values.
argv = CSLSetNameValue( argv,  "-init", "0" );

// -ts <width> <height>
// The output file size in pixels and lines. 
argv = CSLSetNameValue( argv,  "-ts", "1024 1024" );

// -ot <type>
// Force the output bands to be of the indicated data type.
argv = CSLSetNameValue( argv,  "-ot", "Byte" );

GDALRasterizeOptions * pOptions = GDALRasterizeOptionsNew( argv, NULL );

//------------------------------
// Perform rasterization.
int usageError;
GDALDataset * pDstDataset = static_cast<GDALDataset *>( GDALRasterize(
  dstPath.c_str(), NULL,
  pSrcDataset,
  pOptions,
  &usageError ) );

//------------------------------
// Cleanup.
GDALRasterizeOptionsFree( pOptions );
CSLDestroy( argv );
GDALClose( pSrcDataset );
GDALClose( pDstDataset );

Problem: Invalid arguments

The first problem is that I am providing the rasterization arguments incorrectly. The following error printed to standard output lets me know that I am doing it wrong.

GDAL code 6: Unknown option name '-a=crop_id'

Providing the arguments incorrectly is probably the cause of my other problems.

Problem: Projection and SRS unknown

The following errors printed to standard output.

GDAL code 10: Pointer 'hDS' is NULL in 'GDALGetProjectionRef'.

GDAL code 1: The input vector layer has a SRS, but the output raster dataset SRS is unknown.
Ensure output raster dataset has the same SRS, otherwise results might be incorrect.

Problem: Crash from uninitialized pointer

I eventually crash because of a bad pointer.

First-chance exception at 0x10050ee0 in make_wcf.exe: 0xC0000005: Access violation reading location 0x00000040.
Unhandled exception at 0x10050ee0 in make_wcf.exe: 0xC0000005: Access violation reading location 0x00000040.

Answer 1

The problem was that I was using the wrong CSL* function to build the rasterization argument array. The following works, and GDALRasterize() performs correctly without errors.

//------------------------------
// Rasterize options.
char ** argv = NULL;

argv = CSLAddString( argv, "-a" );
argv = CSLAddString( argv, "crop_id" );

argv = CSLAddString( argv, "-l" );
argv = CSLAddString( argv, pSrcLayer->GetName() );

argv = CSLAddString( argv, "-init" );
argv = CSLAddString( argv, "0" );

argv = CSLAddString( argv, "-ts" );
argv = CSLAddString( argv, "1024" );
argv = CSLAddString( argv, "1024" );

argv = CSLAddString( argv, "-ot" );
argv = CSLAddString( argv, "byte" );

GDALRasterizeOptions * pOptions = GDALRasterizeOptionsNew( argv, NULL );

... call GDALRasterize() as before ...