[gdal-dev] loading many files with C API

[Yann Chemin]

Hi again,

the first problem was an input output argv[] confusion. I can load 350
files and it is OK. I may have another problem at the pixel level, but
in case i'll start a new thread.

Thank you Ivan for your suggestion, it would be meaningful indeed to do that.

void usage()
{
	printf( "-----------------------------------------------------------\n");
	printf( "--Calculate the frequency of occurrence of an event--------\n");
	printf( "-----------------------------------------------------------\n");
	printf( "./freq outFREQ infile1[ infile2 infile3 ...] \n");
	printf( "-----------------------------------------------------------\n");
	return;
}

int main( int argc, char *argv[] )
{
      	if( argc < 5 ) {
		usage();
		return 1;
	}
	int 	i, row, col;
        char	*in[MAXFILES];
	char	*out;
	int 	imgs_per_year;
	int	n_imgs;
	int 	n_null_pix;
	GDALDatasetH hDataset[MAXFILES+1];
	GDALAllRegister();
	GDALDriverH hDriver[MAXFILES+1];
	GDALRasterBandH hBand[MAXFILES+1];
	float *pafScanline[MAXFILES+1];
	int nXSize1, nYSize1;

	out	 	= argv[1];

	//Loading input files
	n_imgs = argc - 2;
	for (i=0;i<n_imgs;i++){
		printf("%i / %i %s\n",i,n_imgs,argv[i+2]);
		in[i]	= argv[i+2];
		hDataset[i] = GDALOpen(in[i],GA_ReadOnly);
		hDriver[i] = GDALGetDatasetDriver(hDataset[i]);
		hBand[i] = GDALGetRasterBand(hDataset[i],1);
		nXSize1 = GDALGetRasterBandXSize(hBand[0]);
		pafScanline[i] = (float *) CPLMalloc(sizeof(float)*nXSize1);
	}
	printf("Passed 1\n");
	nYSize1 = GDALGetRasterBandYSize(hBand[0]);

	//Creating output file
	hDataset[n_imgs] = GDALCreateCopy( hDriver[0], out,
				hDataset[0],FALSE,NULL,NULL,NULL);
	hBand[n_imgs] = GDALGetRasterBand(hDataset[n_imgs],1);
	pafScanline[n_imgs] = (float *) CPLMalloc(sizeof(float)*nXSize1);
	////////////////// LOAD Pixels and process from there
/////////////////////////////
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

Thanks
Yann

2008/11/25 Ivan Lucena <ivan.lucena at pmldnet.com>:
> Yann, Frank,
>
> Another thing to considerer is that any process you might want to do on that
> file storage option will be way much slower than if it was done in a multi
> band, tiled, interleaved by pixel format.
>
> That is my experience,
>
> Ivan
>
> Frank Warmerdam wrote:
>>
>> Yann Chemin wrote:
>>>
>>> Hello,
>>>
>>> I need to load about 400 files with the C API to work on each pixel
>>> temporal dimension.
>>>
>>> I would like to make a look to load them but fail so far...
>>>
>>> GDALDatasetH hDataset[MAXFILES];
>>> GDALAllRegister();
>>> GDALDriverH hDriver[MAXFILES];
>>> GDALRasterBandH hBand[MAXFILES];
>>> float *pafScanline[MAXFILES];
>>> int nXSize1,nYSize1;
>>>
>>> //loading input files
>>> for(i=0;i<n_imgs;i++){
>>>    in[i] = argv[i+1];
>>>    hDataset[i] = GDALOpen(in[i];GA_ReadOnly);
>>>    hDriver[i] = GDALDatasetDriver(hDataset[i]);
>>>    hBand[i] = GDALGetRasterBand(hDataset[i],1);
>>>    nXSize1 = GDALGetRasterBandXSize(hBand[0]);
>>>    pafScanline[i] = (float *) CPLMalloc(sizeof(float)*nXSize1);
>>> }
>>>
>>> it mentions error 10: 'hDataset' is NULL in 'GDALGetDatasetDriver'
>>
>> Yann,
>>
>> Is that the first error reported?  Does it occur for i==0 or much later
>> (perhaps around the 250th file)? Many operating systems have a limit
>> on the number of files that can be open at once, in some cases around
>> 256.
>>
>> Best regards,
>
>



-- 
Yann Chemin
International Rice Research Institute
Office: http://www.irri.org/gis
Perso: http://www.freewebs.com/ychemin
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