gis_utils.cpp File Reference

Various GIS-related functions, requires GDAL. More...

#include <assert.h>
#include <iostream>
#include <cmath>
#include <cfloat>
#include <gdal_priv.h>
#include <ogrsf_frmts.h>
#include "cme.h"
#include "simulation.h"
#include "coast.h"
#include "raster_grid.h"

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Detailed Description

Various GIS-related functions, requires GDAL.

Note re. coordinate systems used

1. In the raster CRS, cell[0][0] is at the top left (NW) corner of the grid. Raster grid co-oordinate [0][0] is actually the top left (NW) corner of this cell.

2. We assume that the grid CRS and external CRS have parallel axes. If they have not, see http://www.gdal.org/classGDALDataset.html which says that:

   To convert between pixel/line (P,L) raster space, and projection coordinates (Xp,Yp) space Xp = padfTransform[0] + padfTransform[1] + padfTransform[2]; Yp = padfTransform[3] + padfTransform[4] + padfTransform[5];

   In a north-up image, padfTransform[1] is the pixel width, and padfTransform[5] is the pixel height. The upper left corner of the upper left pixel is at position (padfTransform[0], padfTransform[3]).

3. Usually, raster grid CRS values are integer, i.e. they refer to a point which is at the centroid of a cell. They may also be -ve or greater than m_nXGridSize-1 i.e. may refer to a point which lies outside any cell of the raster grid.

   Author

   David Favis-Mortlock

   Andres Payo

   Date

   2025

   Copyright

   GNU General Public License

Definition in file gis_utils.cpp.