SDTS_AL
|
#include <sdts_al.h>
Public Member Functions | |
int | GetRasterType () |
int | GetTransform (double *) |
int | GetMinMax (double *pdfMin, double *pdfMax, double dfNoData) |
int | GetXSize () |
int | GetYSize () |
int | GetBlockXSize () |
int | GetBlockYSize () |
int | GetBlock (int nXOffset, int nYOffset, void *pData) |
Class for reading raster data from a raster layer.
This class is somewhat unique among the reader classes in that it isn't derived from SDTSIndexedFeature, and it doesn't return "features". Instead it is used to read raster blocks, in the natural block size of the dataset.
int SDTSRasterReader::GetBlock | ( | int | nXOffset, |
int | nYOffset, | ||
void * | pData | ||
) |
Read a block of raster data from the file.
nXOffset | X block offset into the file. Normally zero for scanline organized raster files. |
nYOffset | Y block offset into the file. Normally the scanline offset from top of raster for scanline organized raster files. |
pData | pointer to GInt16 (signed short) buffer of data into which to read the raster. |
|
inline |
Fetch the width of a source block (usually same as raster width).
|
inline |
Fetch the height of a source block (usually one).
int SDTSRasterReader::GetMinMax | ( | double * | pdfMin, |
double * | pdfMax, | ||
double | dfNoData | ||
) |
Fetch the minimum and maximum raster values that occur in the file.
Note this operation current results in a scan of the entire file.
pdfMin | variable in which the minimum value encountered is returned. |
pdfMax | variable in which the maximum value encountered is returned. |
dfNoData | a value to ignore when computing min/max, defaults to -32766. |
int SDTSRasterReader::GetRasterType | ( | ) |
Fetch the pixel data type.
Returns one of SDTS_RT_INT16 (1) or SDTS_RT_FLOAT32 (6) indicating the type of buffer that should be passed to GetBlock().
int SDTSRasterReader::GetTransform | ( | double * | padfTransformOut | ) |
Fetch the transformation between pixel/line coordinates and georeferenced coordinates.
padfTransformOut | pointer to an array of six doubles which will be filled with the georeferencing transform. |
The padfTransformOut array consists of six values. The pixel/line coordinate (Xp,Yp) can be related to a georeferenced coordinate (Xg,Yg) or (Easting, Northing).
Xg = padfTransformOut[0] + Xp * padfTransform[1] + Yp * padfTransform[2] Yg = padfTransformOut[3] + Xp * padfTransform[4] + Yp * padfTransform[5]
In other words, for a north up image the top left corner of the top left pixel is at georeferenced coordinate (padfTransform[0],padfTransform[3]) the pixel width is padfTransform[1], the pixel height is padfTransform[5] and padfTransform[2] and padfTransform[4] will be zero.
|
inline |
Fetch the raster width.
|
inline |
Fetch the raster height.