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- /*--------------------------------------------------------------------
- * The GMT-system: @(#)gmt_grd.h 3.18 01/13/00
- *
- * Copyright (c) 1991-2000 by P. Wessel and W. H. F. Smith
- * See COPYING file for copying and redistribution conditions.
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; version 2 of the License.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * Contact info: www.soest.hawaii.edu/gmt
- *--------------------------------------------------------------------*/
- /*
- * grd.h contains the definition for a GMT-SYSTEM Version >= 2 grd file
- *
- * grd is stored in rows going from west (xmin) to east (xmax)
- * first row in file has yvalue = north (ymax).
- * This is SCANLINE orientation.
- *
- * Author: Paul Wessel
- * Date: 26-MAY-1990
- * Revised: 21-OCT-1998
- */
- /* Nodes that are unconstrained are assumed to be set to NaN */
- #define GRD_COMMAND_LEN 320
- #define GRD_REMARK_LEN 160
- #define GRD_TITLE_LEN 80
- #define GRD_UNIT_LEN 80
- struct GRD_HEADER
- {
- int nx; /* Number of columns */
- int ny; /* Number of rows */
- int node_offset; /* 0 for node grids, 1 for pixel grids */
- double x_min; /* Minimum x coordinate */
- double x_max; /* Maximum x coordinate */
- double y_min; /* Minimum y coordinate */
- double y_max; /* Maximum y coordinate */
- double z_min; /* Minimum z value */
- double z_max; /* Maximum z value */
- double x_inc; /* x increment */
- double y_inc; /* y increment */
- double z_scale_factor; /* grd values must be multiplied by this */
- double z_add_offset; /* After scaling, add this */
- char x_units[GRD_UNIT_LEN]; /* units in x-direction */
- char y_units[GRD_UNIT_LEN]; /* units in y-direction */
- char z_units[GRD_UNIT_LEN]; /* grid value units */
- char title[GRD_TITLE_LEN]; /* name of data set */
- char command[GRD_COMMAND_LEN]; /* name of generating command */
- char remark[GRD_REMARK_LEN]; /* comments re this data set */
- };
- /*-----------------------------------------------------------------------------------------
- * Notes on node_offset:
- Assume x_min = y_min = 0 and x_max = y_max = 10 and x_inc = y_inc = 1.
- For a normal node grid we have:
- (1) nx = (x_max - x_min) / x_inc + 1 = 11
- ny = (y_max - y_min) / y_inc + 1 = 1
- (2) node # 0 is at (x,y) = (x_min, y_max) = (0,10) and represents the surface
- value in a box with dimensions (1,1) centered on the node.
- For a pixel grid we have:
- (1) nx = (x_max - x_min) / x_inc = 10
- ny = (y_max - y_min) / y_inc = 10
- (2) node # 0 is at (x,y) = (x_min + 0.5*x_inc, y_max - 0.5*y_inc) = (0.5, 9.5)
- and represents the surface value in a box with dimensions (1,1)
- centered on the node.
- -------------------------------------------------------------------------------------------*/
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