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/*--------------------------------------------------------------------
* $Id: grdgradient.c 10173 2014-01-01 09:52:34Z pwessel $
*
* Copyright (c) 1991-2014 by P. Wessel and W. H. F. Smith
* See LICENSE.TXT 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 or any later version.
*
* 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: gmt.soest.hawaii.edu
*--------------------------------------------------------------------*/
/*
* grdgradient.c
* read a grid file and compute gradient in azim direction:
*
* azim = azimuth clockwise from north in degrees.
*
* gradient = -[(dz/dx)sin(azim) + (dz/dy)cos(azim)].
*
* the expression in [] is the correct gradient. We take
* -[] in order that data which goes DOWNHILL in the
* azim direction will give a positive value; this is
* for image shading purposes.
*
*
* Author: W.H.F. Smith
* Date: 13 Feb 1991
* Upgraded to v2.0 15-May-1991 Paul Wessel
*
* Modified: 1 Mar 94 by WHFS to make -M scale change with j latitude
* 1 Mar 96 by PW to find gradient direction and magnitude (-S and -D)
* 13 Mar 96 by WHFS to add exp trans and user-supplied sigma to -N
* option, and add optional second azimuth to -A option.
* 11 Sep 97 by PW now may pass average gradient along with sigma in -N
* 22 Apr 98 by WHFS to add boundary conditions, switch sense of -S and
* -D, and switch -Da to -Dc, for consistency of args.
* 6 Sep 05 by J. Luis, added a -E option that allows the Lambertian or
* Peucker piecewise linear radiance computations
* Version: 4
*/
#include "gmt.h"
struct GRDGRADIENT_CTRL {
struct A { /* -A<azim>[/<azim2>] */
GMT_LONG active;
GMT_LONG two;
double azimuth[2];
} A;
struct D { /* -D[a][o][n] */
GMT_LONG active;
GMT_LONG mode;
} D;
struct E { /* -E[s|p]<azim>/<elev[ambient/diffuse/specular/shine]> */
GMT_LONG active;
double azimuth, elevation;
double ambient, diffuse, specular, shine;
GMT_LONG mode;
} E;
struct G { /* -G<file> */
GMT_LONG active;
char *file;
} G;
struct L { /* -L<flag> */
GMT_LONG active;
char mode[4];
} L;
struct M { /* -M */
GMT_LONG active;
} M;
struct N { /* -N[t_or_e][<amp>[/<sigma>[/<offset>]]] */
GMT_LONG active;
GMT_LONG mode;
double norm, sigma, offset;
} N;
struct S { /* -S<slopefile> */
GMT_LONG active;
char *file;
} S;
};
EXTERN_MSC GMT_LONG GMT_parse_f_option (char *arg); /* Needed for -L setup */
int main (int argc, char **argv)
{
char *infile = CNULL, format[BUFSIZ], ptr[BUFSIZ];
GMT_LONG error = FALSE, sigma_set = FALSE, offset_set = FALSE, bad;
GMT_LONG pos, p[4], entry, mx, my;
GMT_LONG i, j, ij, k, n, nm, nm2, n_used = 0;
float *data = NULL, *slp = VNULL;
double dx_grid, dy_grid, x_factor, y_factor, dzdx, dzdy, ave_gradient;
double azim, denom, max_gradient = 0.0, min_gradient = 0.0, rpi, lat;
double x_factor2 = 0.0, y_factor2 = 0.0, dzdx2 = 0.0, dzdy2 = 0.0, dzds1, dzds2;
double p0 = 0.0, q0 = 0.0, p0q0_cte = 1.0, norm_z, mag, s[3], lim_x, lim_y, lim_z;
double k_ads = 0.0, diffuse, spec, r_min = DBL_MAX, r_max = -DBL_MAX, scale;
struct GRD_HEADER header;
struct GMT_EDGEINFO edgeinfo;
struct GRDGRADIENT_CTRL *Ctrl = NULL;
double specular (double nx, double ny, double nz, double *s);
void *New_grdgradient_Ctrl (), Free_grdgradient_Ctrl (struct GRDGRADIENT_CTRL *C);
argc = (int)GMT_begin (argc, argv);
Ctrl = (struct GRDGRADIENT_CTRL *)New_grdgradient_Ctrl (); /* Allocate and initialize a new control structure */
GMT_boundcond_init (&edgeinfo);
memset ((void *)s, 0, 3*sizeof(double));
for (i = 1; i < argc; i++) {
if (argv[i][0] == '-') {
switch (argv[i][1]) {
/* Common parameters */
case 'V':
case '\0':
error += GMT_parse_common_options (argv[i], 0, 0, 0, 0);
break;
/* Supplemental parameters */
case 'A':
Ctrl->A.active = TRUE;
j = sscanf(&argv[i][2], "%lf/%lf", &Ctrl->A.azimuth[0], &Ctrl->A.azimuth[1]);
Ctrl->A.two = (j == 2);
break;
case 'D':
Ctrl->D.active = TRUE;
j = 2;
while (argv[i][j]) {
switch (argv[i][j]) {
case 'C':
case 'c':
Ctrl->D.mode |= 1;
break;
case 'O':
case 'o':
Ctrl->D.mode |= 2;
break;
case 'N':
case 'n':
Ctrl->D.mode |= 4;
break;
default:
fprintf (stderr, "%s: GMT SYNTAX ERROR -D option: Unrecognized modifier\n", GMT_program);
error++;
break;
}
j++;
}
break;
case 'E': /* Lambertian family radiance */
Ctrl->E.active = TRUE;
switch (argv[i][2]) {
case 'p': /* Peucker */
Ctrl->E.mode = 1;
break;
case 's': /* "simple" Lambertian case */
Ctrl->E.mode = 2;
if (sscanf(&argv[i][3], "%lf/%lf", &Ctrl->E.azimuth, &Ctrl->E.elevation) != 2) {
fprintf(stderr,"%s: GMT SYNTAX ERROR -Es option: Must append azimuth/elevation\n", GMT_program);
error++;
}
break;
default:
Ctrl->E.mode = 3; /* "full" Lambertian case */
if (sscanf(&argv[i][2], "%lf/%lf", &Ctrl->E.azimuth, &Ctrl->E.elevation) < 2) {
fprintf(stderr,"%s: GMT SYNTAX ERROR -E option: Must give at least azimuth and elevation\n", GMT_program);
error++;
}
entry = pos = 0;
while (entry < 6 && (GMT_strtok (&argv[i][2], "/", &pos, ptr))) {
switch (entry) {
case 0:
case 1:
break; /* Cases already processed above */
case 2:
if (ptr[0] != '=') Ctrl->E.ambient = atof (ptr);
break;
case 3:
if (ptr[0] != '=') Ctrl->E.diffuse = atof (ptr);
break;
case 4:
if (ptr[0] != '=') Ctrl->E.specular = atof (ptr);
break;
case 5:
if (ptr[0] != '=') Ctrl->E.shine = atof (ptr);
break;
default:
break;
}
entry++;
}
break;
}
break;
case 'G':
Ctrl->G.active = TRUE;
Ctrl->G.file = strdup (&argv[i][2]);
break;
case 'L':
Ctrl->L.active = TRUE;
strncpy (Ctrl->L.mode, &argv[i][2], (size_t)4);
/* We turn on geographic coordinates if -Lg is given by faking -fg */
if (! strcmp (Ctrl->L.mode, "g")) GMT_parse_f_option ("g");
break;
case 'M':
Ctrl->M.active = TRUE;
break;
case 'N':
Ctrl->N.active = TRUE;
j = 2;
if (argv[i][j]) {
if (argv[i][j] == 't' || argv[i][j] == 'T') {
Ctrl->N.mode = 1;
j++;
}
else if (argv[i][j] == 'e' || argv[i][j] == 'E') {
Ctrl->N.mode = 2;
j++;
}
j = sscanf(&argv[i][j], "%lf/%lf/%lf", &Ctrl->N.norm, &Ctrl->N.sigma, &Ctrl->N.offset);
}
break;
case 'S':
Ctrl->S.active = TRUE;
Ctrl->S.file = strdup (&argv[i][2]);
break;
default:
error = TRUE;
GMT_default_error (argv[i][1]);
break;
}
}
else
infile = argv[i];
}
if (argc == 1 || GMT_give_synopsis_and_exit) {
fprintf (stderr,"grdgradient %s - Compute directional gradients from grid files\n\n", GMT_VERSION);
fprintf (stderr, "usage: grdgradient <infile> -G<outfile> [-A<azim>[/<azim2>]] [-D[a][o][n]]\n");
fprintf (stderr, "[-E[s|p]<azim>/<elev[ambient/diffuse/specular/shine]>]\n");
fprintf (stderr, "[-L<flag>] [-M] [-N[t_or_e][<amp>[/<sigma>[/<offset>]]]] [-S<slopefile>] [-V]\n\n");
if (GMT_give_synopsis_and_exit) exit (EXIT_FAILURE);
fprintf (stderr,"\t<infile> is name of input grid file.\n");
fprintf (stderr,"\n\tOPTIONS:\n");
fprintf (stderr, "\t-A sets azimuth (0-360 CW from North (+y)) for directional derivatives.\n");
fprintf (stderr, "\t -A<azim>/<azim2> will compute two directions and save the one larger in magnitude.\n");
fprintf (stderr, "\t-D finds the direction of grad z.\n");
fprintf (stderr, "\t Append c to get cartesian angle (0-360 CCW from East (+x)) [Default: azimuth].\n");
fprintf (stderr, "\t Append o to get bidirectional orientations [0-180] rather than directions [0-360].\n");
fprintf (stderr, "\t Append n to add 90 degrees to the values from c or o.\n");
fprintf (stderr, "\t-E Compute Lambertian radiance appropriate to use with grdimage/grdview.\n");
fprintf (stderr, "\t -E<azim/elev> sets azimuth and elevation of light vector.\n");
fprintf (stderr, "\t -E<azim/elev/ambient/diffuse/specular/shine> sets azim, elev and\n");
fprintf (stderr, "\t other parameters that control the reflectance properties of the surface.\n");
fprintf (stderr, "\t Default values are: 0.55/0.6/0.4/10.\n");
fprintf (stderr, "\t Specify '=' to get the default value (e.g., -E60/30/=/0.5).\n");
fprintf (stderr, "\t Append s to use a simpler Lambertian algorithm (note that with this form\n");
fprintf (stderr, "\t you only have to provide the azimuth and elevation parameters).\n");
fprintf (stderr, "\t Append p to use the Peucker piecewise linear approximation (simpler but faster algorithm).\n");
fprintf (stderr, "\t Note that in this case the azimuth and elevation are hardwired to 315 and 45 degrees.\n");
fprintf (stderr, "\t This means that even if you provide other values they will be ignored.\n");
fprintf (stderr, "\t-G output file for results from -A or -D.\n");
fprintf (stderr, "\t-L sets boundary conditions. <flag> can be either:\n");
fprintf (stderr, "\t g for geographic boundary conditions\n");
fprintf (stderr, "\t or one or both of\n");
fprintf (stderr, "\t x for periodic boundary conditions on x\n");
fprintf (stderr, "\t y for periodic boundary conditions on y\n");
fprintf (stderr, "\t [Default: Natural conditions].\n");
fprintf (stderr, "\t-M to use map units. In this case, dx,dy of grid\n");
fprintf (stderr, "\t will be converted from degrees lon,lat into meters (Flat-earth approximation).\n");
fprintf (stderr, "\t Default computes gradient in units of data/grid_distance.\n");
fprintf (stderr, "\t-N will normalize gradients so that max |grad| = <amp> [1.0].\n");
fprintf (stderr, "\t -Nt will make atan transform, then scale to <amp> [1.0].\n");
fprintf (stderr, "\t -Ne will make exp transform, then scale to <amp> [1.0].\n");
fprintf (stderr, "\t -Nt<amp>/<sigma>[/<offset>] or -Ne<amp>/<sigma>[/<offset>] sets sigma\n");
fprintf (stderr, "\t (and offset) for transform. [sigma, offset estimated from data].\n");
fprintf (stderr, "\t-S output file for |grad z|; requires -D.\n");
GMT_explain_option ('V');
exit (EXIT_FAILURE);
}
if (!(Ctrl->A.active || Ctrl->D.active || Ctrl->E.active)) {
fprintf (stderr, "%s: GMT SYNTAX ERROR: Must specify -A, -D, or -E\n", GMT_program);
error++;
}
if (Ctrl->S.active && !Ctrl->S.file) {
fprintf (stderr, "%s: GMT SYNTAX ERROR -S option: Must specify output file\n", GMT_program);
error++;
}
if (!Ctrl->G.file && !Ctrl->S.active) {
fprintf (stderr, "%s: GMT SYNTAX ERROR -G option: Must specify output file\n", GMT_program);
error++;
}
if (!infile) {
fprintf (stderr, "%s: GMT SYNTAX ERROR: Must specify input file\n", GMT_program);
error++;
}
if (Ctrl->N.norm <= 0.0) {
fprintf (stderr, "%s: GMT SYNTAX ERROR -N option: Normalization amplitude must be > 0\n", GMT_program);
error++;
}
if (sigma_set && (Ctrl->N.sigma <= 0.0) ) {
fprintf (stderr, "%s: GMT SYNTAX ERROR -N option: Sigma must be > 0\n", GMT_program);
error++;
}
if (Ctrl->E.active && Ctrl->E.mode > 1 && (Ctrl->E.elevation < 0.0 || Ctrl->E.elevation > 90.0)) {
fprintf (stderr, "%s: GMT SYNTAX ERROR -E option: Use 0-90 degree range for elevation\n", GMT_program);
error++;
}
if (Ctrl->E.active && (Ctrl->A.active || Ctrl->D.active || Ctrl->S.active)) {
fprintf (stderr, "%s: WARNING: -E option overrides -A, -D or -S\n", GMT_program);
Ctrl->A.active = Ctrl->D.active = Ctrl->S.active = FALSE;
}
if (Ctrl->L.active && GMT_boundcond_parse (&edgeinfo, Ctrl->L.mode)) error++;
if (error) exit (EXIT_FAILURE);
GMT_err_fail (GMT_read_grd_info (infile, &header), infile);
if (Ctrl->N.active && Ctrl->N.sigma != 0.0) sigma_set = TRUE;
if (Ctrl->N.active && Ctrl->N.offset != 0.0) offset_set = TRUE;
if (Ctrl->A.active) {
while (Ctrl->A.azimuth[0] < 0.0) Ctrl->A.azimuth[0] += 360.0;
while (Ctrl->A.azimuth[0] > 360.0) Ctrl->A.azimuth[0] -= 360.0;
if (Ctrl->A.two) {
while (Ctrl->A.azimuth[1] < 0.0) Ctrl->A.azimuth[1] += 360.0;
while (Ctrl->A.azimuth[1] > 360.0) Ctrl->A.azimuth[1] -= 360.0;
}
}
if (Ctrl->E.active) {
while (Ctrl->E.azimuth < 0.0) Ctrl->E.azimuth += 360.0;
while (Ctrl->E.azimuth > 360.0) Ctrl->E.azimuth -= 360.0;
}
if (Ctrl->E.mode == 2) {
p0 = cosd(90.0 - Ctrl->E.azimuth) * tand(90.0 - Ctrl->E.elevation);
q0 = sind(90.0 - Ctrl->E.azimuth) * tand(90.0 - Ctrl->E.elevation);
p0q0_cte = sqrt(1 + p0*p0 + q0*q0);
}
if (Ctrl->E.mode == 3) {
Ctrl->E.elevation = 90 - Ctrl->E.elevation;
s[0] = sind(Ctrl->E.azimuth) * cosd(Ctrl->E.elevation);
s[1] = cosd(Ctrl->E.azimuth) * cosd(Ctrl->E.elevation);
s[2] = sind(Ctrl->E.elevation);
k_ads = Ctrl->E.ambient + Ctrl->E.diffuse + Ctrl->E.specular;
}
GMT_boundcond_param_prep (&header, &edgeinfo);
GMT_grd_init (&header, argc, argv, TRUE);
nm = GMT_get_nm (header.nx, header.ny);
mx = header.nx + 4;
my = header.ny + 4;
nm2 = GMT_get_nm (mx, my);
data = (float *) GMT_memory (VNULL, (size_t)nm2, sizeof (float), GMT_program);
GMT_pad[0] = GMT_pad[1] = GMT_pad[2] = GMT_pad[3] = 2;
if (Ctrl->S.active) slp = (float *) GMT_memory (VNULL, (size_t)nm, sizeof (float), GMT_program);
GMT_err_fail (GMT_read_grd (infile, &header, data, header.x_min, header.x_max, header.y_min, header.y_max, GMT_pad, FALSE), infile);
/* set boundary conditions: */
GMT_boundcond_set (&header, &edgeinfo, GMT_pad, data);
if (Ctrl->M.active) {
dx_grid = project_info.DIST_M_PR_DEG * header.x_inc * cosd ((header.y_max + header.y_min) / 2.0);
dy_grid = project_info.DIST_M_PR_DEG * header.y_inc;
}
else {
dx_grid = header.x_inc;
dy_grid = header.y_inc;
}
x_factor = -1.0 / (2.0 * dx_grid);
y_factor = -1.0 / (2.0 * dy_grid);
if (Ctrl->A.active) {
if (Ctrl->A.two) {
Ctrl->A.azimuth[1] *= (M_PI / 180.0);
x_factor2 = x_factor * sin (Ctrl->A.azimuth[1]);
y_factor2 = y_factor * cos( Ctrl->A.azimuth[1]);
}
Ctrl->A.azimuth[0] *= (M_PI / 180.0);
x_factor *= sin (Ctrl->A.azimuth[0]);
y_factor *= cos (Ctrl->A.azimuth[0]);
}
p[0] = 1; p[1] = -1; p[2] = mx; p[3] = -mx;
min_gradient = DBL_MAX; max_gradient = -DBL_MAX;
ave_gradient = 0.0;
if (Ctrl->E.mode == 3) {
lim_x = header.x_max - header.x_min;
lim_y = header.y_max - header.y_min;
lim_z = header.z_max - header.z_min;
scale = MAX(lim_z, MAX(lim_x, lim_y));
lim_x /= scale; lim_y /= scale; lim_z /= scale;
dx_grid /= lim_x; dy_grid /= lim_y;
x_factor = -dy_grid / (2 * lim_z); y_factor = -dx_grid / (2 * lim_z);
}
for (j = k = 0; j < header.ny; j++) {
if (Ctrl->M.active) {
lat = GMT_j_to_y (j, header.y_min, header.y_max, header.y_inc, 0.5 * header.node_offset, header.ny);
dx_grid = project_info.DIST_M_PR_DEG * header.x_inc * cosd (lat);
if (dx_grid > 0.0) x_factor = -1.0 / (2.0 * dx_grid); /* Use previous value at the poles */
if (Ctrl->A.active) {
if (Ctrl->A.two) {
x_factor2 = x_factor * sin(Ctrl->A.azimuth[1]);
}
x_factor *= sin(Ctrl->A.azimuth[0]);
}
}
for (i = 0; i < header.nx; i++, k++) {
ij = (j + 2) * mx + i + 2;
for (n = 0, bad = FALSE; !bad && n < 4; n++) if (GMT_is_fnan (data[ij+p[n]])) bad = TRUE;
if (bad) { /* One of corners = NaN, skip */
data[k] = GMT_f_NaN;
if (Ctrl->S.active) slp[k] = GMT_f_NaN;
continue;
}
dzdx = (data[ij+1] - data[ij-1]) * x_factor;
dzdy = (data[ij-mx] - data[ij+mx]) * y_factor;
if (Ctrl->A.two) {
dzdx2 = (data[ij+1] - data[ij-1]) * x_factor2;
dzdy2 = (data[ij-mx] - data[ij+mx]) * y_factor2;
}
/* Write output to unused NW corner */
if (Ctrl->A.active) { /* Directional derivatives */
if (Ctrl->A.two) {
dzds1 = dzdx + dzdy;
dzds2 = dzdx2 + dzdy2;
data[k] = (float)((fabs(dzds1) > fabs(dzds2)) ? dzds1 : dzds2);
}
else {
data[k] = (float)(dzdx + dzdy);
}
ave_gradient += data[k];
min_gradient = MIN (min_gradient, data[k]);
max_gradient = MAX (max_gradient, data[k]);
}
else if (Ctrl->D.active) {
azim = (Ctrl->D.mode & 1) ? atan2d (-dzdy, -dzdx) : 90.0 - atan2d (-dzdy, -dzdx);
if (Ctrl->D.mode & 4) azim += 90.0;
if (azim < 0.0) azim += 360.0;
if (azim >= 360.0) azim -= 360.0;
if (Ctrl->D.mode & 2 && azim >= 180) azim -= 180.0;
data[k] = (float)azim;
if (Ctrl->S.active) slp[k] = (float)hypot (dzdx, dzdy);
}
else { /* Ctrl->E.active */
if (Ctrl->E.mode == 3) {
norm_z = dx_grid * dy_grid;
mag = d_sqrt(dzdx*dzdx + dzdy*dzdy + norm_z*norm_z);
dzdx /= mag; dzdy /= mag; norm_z /= mag;
diffuse = MAX(0,(s[0]*dzdx + s[1]*dzdy + s[2]*norm_z));
spec = specular(dzdx, dzdy, norm_z, s);
spec = pow(spec, Ctrl->E.shine);
data[k] = (float)((Ctrl->E.ambient+Ctrl->E.diffuse*diffuse+Ctrl->E.specular*spec) / k_ads);
}
else if (Ctrl->E.mode == 2)
data[k] = (float)( (1 + p0*dzdx + q0*dzdy) / (sqrt(1 + dzdx*dzdx + dzdy*dzdy) * p0q0_cte) );
else /* Peucker method */
data[k] = (float)( -0.4285 * (dzdx - dzdy) - 0.0844 * fabs(dzdx + dzdy) + 0.6599 );
r_min = MIN (r_min, (double)data[k]);
r_max = MAX (r_max, (double)data[k]);
}
n_used++;
}
}
if (Ctrl->M.active || GMT_io.in_col_type[GMT_Y] == GMT_IS_LAT) { /* Data is geographic */
double sum;
/* If the N or S poles are included then we only want a single estimate at these repeating points */
if (header.y_min == -90.0 && header.node_offset == 0) { /* Average all the multiple N pole estimates */
for (k = 0, sum = 0.0; k < header.nx; k++) sum += data[k];
sum /= header.nx; /* Average NP gradient */
for (k = 0; k < header.nx; k++) data[k] = (float)sum;
}
if (header.y_min == -90.0 && header.node_offset == 0) { /* Average all the multiple S pole estimates */
for (i = 0, k = header.nx * (header.ny - 1), sum = 0.0; i < header.nx; i++, k++) sum += data[k];
sum /= header.nx; /* Average SP gradient */
for (i = 0, k = header.nx * (header.ny - 1); i < header.nx; i++, k++) data[k] = (float)sum;
}
}
if (Ctrl->E.active) { /* data must be scaled to the [-1,1] interval, but we'll do it into [-.95, .95] to not get too bright */
scale = 1.0 / (r_max - r_min);
for (k = 0; k < nm; k++) {
if (GMT_is_fnan (data[k])) continue;
data[k] = (float)((-1.0 + 2.0 * ((data[k] - r_min) * scale)) * 0.95);
}
}
if (offset_set)
ave_gradient = Ctrl->N.offset;
else
ave_gradient /= n_used;
if (Ctrl->A.active) { /* Report some statistics */
if (Ctrl->N.active) {
if (Ctrl->N.mode == 1) {
if (sigma_set) {
denom = 1.0 / Ctrl->N.sigma;
}
else {
denom = 0.0;
for (k = 0; k < nm; k++) if (!GMT_is_fnan (data[k])) denom += pow(data[k] - ave_gradient, 2.0);
denom = sqrt( (n_used - 1) / denom);
Ctrl->N.sigma = 1.0 / denom;
}
rpi = 2.0 * Ctrl->N.norm / M_PI;
for (k = 0; k < nm; k++) if (!GMT_is_fnan (data[k])) data[k] = (float)(rpi * atan((data[k] - ave_gradient)*denom));
header.z_max = rpi * atan((max_gradient - ave_gradient)*denom);
header.z_min = rpi * atan((min_gradient - ave_gradient)*denom);
}
else if (Ctrl->N.mode == 2) {
if (!sigma_set) {
Ctrl->N.sigma = 0.0;
for (k = 0; k < nm; k++) if (!GMT_is_fnan (data[k])) Ctrl->N.sigma += fabs((double)data[k]);
Ctrl->N.sigma = M_SQRT2 * Ctrl->N.sigma / n_used;
}
denom = M_SQRT2 / Ctrl->N.sigma;
for (k = 0; k < nm; k++) {
if (GMT_is_fnan (data[k])) continue;
if (data[k] < ave_gradient) {
data[k] = (float)(-Ctrl->N.norm * (1.0 - exp((data[k] - ave_gradient)*denom)));
}
else {
data[k] = (float)(Ctrl->N.norm * (1.0 - exp(-(data[k] - ave_gradient)*denom)));
}
}
header.z_max = Ctrl->N.norm * (1.0 - exp(-(max_gradient - ave_gradient)*denom));
header.z_min = -Ctrl->N.norm * (1.0 - exp((min_gradient - ave_gradient)*denom));
}
else {
if ( (max_gradient - ave_gradient) > (ave_gradient - min_gradient) ) {
denom = Ctrl->N.norm / (max_gradient - ave_gradient);
}
else {
denom = Ctrl->N.norm / (ave_gradient - min_gradient);
}
for (k = 0; k < nm; k++) if (!GMT_is_fnan (data[k])) data[k] = (float)((data[k] - ave_gradient) * denom);
header.z_max = (max_gradient - ave_gradient) * denom;
header.z_min = (min_gradient - ave_gradient) * denom;
}
}
}
/* Now we write out: */
if (Ctrl->A.active) {
if (Ctrl->N.active) {
strcpy (header.title, "Normalized directional derivative(s)");
}
else {
strcpy (header.title, "Directional derivative(s)");
}
sprintf (format, "\t%s\t%s\t%s\t%s\n", gmtdefs.d_format, gmtdefs.d_format, gmtdefs.d_format, gmtdefs.d_format);
if (gmtdefs.verbose) {
fprintf (stderr, "%s: Min Mean Max sigma intensities:", GMT_program);
fprintf (stderr, format, min_gradient, ave_gradient, max_gradient, Ctrl->N.sigma);
}
}
else {
if (Ctrl->E.mode > 1)
strcpy (header.title, "Lambertian radiance");
else if (Ctrl->E.mode == 1)
strcpy (header.title, "Peucker piecewise linear radiance");
else
strcpy (header.title, "Directions of maximum slopes");
}
GMT_pad[0] = GMT_pad[1] = GMT_pad[2] = GMT_pad[3] = 0; /* Because of the shift */
if (Ctrl->G.active)
GMT_err_fail (GMT_write_grd (Ctrl->G.file, &header, data, 0.0, 0.0, 0.0, 0.0, GMT_pad, FALSE), Ctrl->G.file);
GMT_free ((void *) data);
if (Ctrl->S.active) {
strcpy (header.title, "Magnitude of maximum slopes");
GMT_err_fail (GMT_write_grd (Ctrl->S.file, &header, slp, 0.0, 0.0, 0.0, 0.0, GMT_pad, FALSE), Ctrl->S.file);
GMT_free ((void *)slp);
}
Free_grdgradient_Ctrl (Ctrl); /* Deallocate control structure */
GMT_end (argc, argv);
exit (EXIT_SUCCESS);
}
double specular (double nx, double ny, double nz, double *s) {
/* SPECULAR Specular reflectance.
R = SPECULAR(Nx,Ny,Nz,S,V) returns the reflectance of a surface with
normal vector components [Nx,Ny,Nz]. S and V specify the direction
to the light source and to the viewer, respectively.
For the time beeing I'm using V = [azim elev] = [0 90] so the following
V[0] = sind(V[0])*cosd(V[1]);
V[1] = -cosd(V[0])*cosd(V[1]);
V[2] = sind(V[1]);
Reduces to V[0] = 0; V[1] = 0; V[2] = 1 */
/*r = MAX(0,2*(s[0]*nx+s[1]*ny+s[2]*nz).*(v[0]*nx+v[1]*ny+v[2]*nz) - (v'*s)*ones(m,n)); */
return (MAX(0, 2 * (s[0]*nx + s[1]*ny + s[2]*nz) * nz - s[2]));
}
void *New_grdgradient_Ctrl () { /* Allocate and initialize a new control structure */
struct GRDGRADIENT_CTRL *C;
C = (struct GRDGRADIENT_CTRL *) GMT_memory (VNULL, (size_t)1, sizeof (struct GRDGRADIENT_CTRL), "New_grdgradient_Ctrl");
/* Initialize values whose defaults are not 0/FALSE/NULL */
C->E.ambient = 0.55;
C->E.diffuse = 0.6;
C->E.specular = 0.4;
C->E.shine = 10;
C->N.norm = 1.0;
return ((void *)C);
}
void Free_grdgradient_Ctrl (struct GRDGRADIENT_CTRL *C) { /* Deallocate control structure */
if (C->G.file) free ((void *)C->G.file);
if (C->S.file) free ((void *)C->S.file);
GMT_free ((void *)C);
}
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