23 |
|
* to reduce the influence of distant neighbors. This yields a |
24 |
|
* smooth interpolation regardless of how the sample points are |
25 |
|
* initially distributed. Evaluation is accelerated by use of |
26 |
< |
* a fast approximation to the atan2(y,x) function. |
26 |
> |
* a fast approximation to the atan2(y,x) function and an array |
27 |
> |
* of flags indicating where weights are (nearly) zero. |
28 |
|
****************************************************************/ |
29 |
|
|
30 |
|
#include <stdio.h> |
156 |
|
{ |
157 |
|
SAMPORD *sortord; |
158 |
|
int *rightrndx, *leftrndx, *endrndx; |
159 |
< |
int bd; |
159 |
> |
int i, bd; |
160 |
|
/* sanity checks */ |
161 |
< |
if (ip == NULL || (ip->ns <= 1) | (ip->dmin <= 0)) |
161 |
> |
if (ip == NULL) |
162 |
|
return(0); |
163 |
< |
/* need to allocate? */ |
164 |
< |
if (ip->da == NULL) { |
165 |
< |
ip->da = (unsigned short (*)[NI2DIR])malloc( |
165 |
< |
sizeof(unsigned short)*NI2DIR*ip->ns); |
166 |
< |
if (ip->da == NULL) |
167 |
< |
return(0); |
163 |
> |
if (ip->da != NULL) { /* free previous data if any */ |
164 |
> |
free(ip->da); |
165 |
> |
ip->da = NULL; |
166 |
|
} |
167 |
+ |
if ((ip->ns <= 1) | (ip->dmin <= 0)) |
168 |
+ |
return(0); |
169 |
+ |
/* compute sample domain */ |
170 |
+ |
ip->smin[0] = ip->smin[1] = FHUGE; |
171 |
+ |
ip->smax[0] = ip->smax[1] = -FHUGE; |
172 |
+ |
for (i = ip->ns; i--; ) { |
173 |
+ |
if (ip->spt[i][0] < ip->smin[0]) |
174 |
+ |
ip->smin[0] = ip->spt[i][0]; |
175 |
+ |
if (ip->spt[i][0] > ip->smax[0]) |
176 |
+ |
ip->smax[0] = ip->spt[i][0]; |
177 |
+ |
if (ip->spt[i][1] < ip->smin[1]) |
178 |
+ |
ip->smin[1] = ip->spt[i][1]; |
179 |
+ |
if (ip->spt[i][1] > ip->smax[1]) |
180 |
+ |
ip->smax[1] = ip->spt[i][1]; |
181 |
+ |
} |
182 |
+ |
ip->grid2 = ((ip->smax[0]-ip->smin[0])*(ip->smax[0]-ip->smin[0]) + |
183 |
+ |
(ip->smax[1]-ip->smin[1])*(ip->smax[1]-ip->smin[1])) * |
184 |
+ |
(1./NI2DIM/NI2DIM); |
185 |
+ |
if (ip->grid2 <= FTINY*ip->dmin*ip->dmin) |
186 |
+ |
return(0); |
187 |
+ |
/* allocate analysis data */ |
188 |
+ |
ip->da = (struct interp2_samp *)calloc( ip->ns, |
189 |
+ |
sizeof(struct interp2_samp) ); |
190 |
+ |
if (ip->da == NULL) |
191 |
+ |
return(0); |
192 |
|
/* get temporary arrays */ |
193 |
|
sortord = (SAMPORD *)malloc(sizeof(SAMPORD)*ip->ns); |
194 |
|
rightrndx = (int *)malloc(sizeof(int)*ip->ns); |
201 |
|
for (bd = 0; bd < NI2DIR/2; bd++) { |
202 |
|
const double ang = 2.*PI/NI2DIR*bd; |
203 |
|
int *sptr; |
181 |
– |
int i; |
204 |
|
/* create right reverse index */ |
205 |
|
if (bd) { /* re-use from previous iteration? */ |
206 |
|
sptr = rightrndx; |
231 |
|
const int ii = sortord[i].si; |
232 |
|
int j; |
233 |
|
/* preload with large radii */ |
234 |
< |
ip->da[ii][bd] = ip->da[ii][bd+NI2DIR/2] = encode_diameter(ip, |
235 |
< |
.5*(sortord[ip->ns-1].dm - sortord[0].dm)); |
234 |
> |
ip->da[ii].dia[bd] = |
235 |
> |
ip->da[ii].dia[bd+NI2DIR/2] = encode_diameter(ip, |
236 |
> |
.5*(sortord[ip->ns-1].dm - sortord[0].dm)); |
237 |
|
for (j = i; ++j < ip->ns; ) /* nearest above */ |
238 |
|
if (rightrndx[sortord[j].si] > rightrndx[ii] && |
239 |
|
leftrndx[sortord[j].si] < leftrndx[ii]) { |
240 |
< |
ip->da[ii][bd] = encode_diameter(ip, |
240 |
> |
ip->da[ii].dia[bd] = encode_diameter(ip, |
241 |
|
sortord[j].dm - sortord[i].dm); |
242 |
|
break; |
243 |
|
} |
244 |
|
for (j = i; j-- > 0; ) /* nearest below */ |
245 |
|
if (rightrndx[sortord[j].si] < rightrndx[ii] && |
246 |
|
leftrndx[sortord[j].si] > leftrndx[ii]) { |
247 |
< |
ip->da[ii][bd+NI2DIR/2] = encode_diameter(ip, |
247 |
> |
ip->da[ii].dia[bd+NI2DIR/2] = encode_diameter(ip, |
248 |
|
sortord[i].dm - sortord[j].dm); |
249 |
|
break; |
250 |
|
} |
257 |
|
return(1); |
258 |
|
} |
259 |
|
|
260 |
< |
/* private call returns raw weight for a particular sample */ |
261 |
< |
static double |
262 |
< |
get_wt(const INTERP2 *ip, const int i, double x, double y) |
260 |
> |
/* Compute unnormalized weight for a position relative to a sample */ |
261 |
> |
double |
262 |
> |
interp2_wti(INTERP2 *ip, const int i, double x, double y) |
263 |
|
{ |
264 |
< |
double dir, rd, r2, d2; |
265 |
< |
int ri; |
264 |
> |
double dir, rd, r2, d2; |
265 |
> |
int ri; |
266 |
|
/* get relative direction */ |
267 |
|
x -= ip->spt[i][0]; |
268 |
|
y -= ip->spt[i][1]; |
272 |
|
rd = dir * (NI2DIR/2./PI); |
273 |
|
ri = (int)rd; |
274 |
|
rd -= (double)ri; |
275 |
< |
rd = (1.-rd)*ip->da[i][ri] + rd*ip->da[i][(ri+1)%NI2DIR]; |
275 |
> |
rd = (1.-rd)*ip->da[i].dia[ri] + rd*ip->da[i].dia[(ri+1)%NI2DIR]; |
276 |
|
rd = ip->smf * DECODE_DIA(ip, rd); |
277 |
|
r2 = 2.*rd*rd; |
278 |
|
d2 = x*x + y*y; |
282 |
|
return( exp(-d2/r2) * ip->dmin/(ip->dmin + sqrt(d2)) ); |
283 |
|
} |
284 |
|
|
285 |
+ |
/* private call to get grid flag index */ |
286 |
+ |
static int |
287 |
+ |
interp2_flagpos(int fgi[2], INTERP2 *ip, double x, double y) |
288 |
+ |
{ |
289 |
+ |
int ingrid = 1; |
290 |
+ |
|
291 |
+ |
if (ip == NULL) /* paranoia */ |
292 |
+ |
return(-1); |
293 |
+ |
/* need to compute interpolant? */ |
294 |
+ |
if (ip->da == NULL && !interp2_analyze(ip)) |
295 |
+ |
return(-1); |
296 |
+ |
/* get grid position */ |
297 |
+ |
fgi[0] = (x - ip->smin[0]) * NI2DIM / (ip->smax[0] - ip->smin[0]); |
298 |
+ |
if (fgi[0] >= NI2DIM) { |
299 |
+ |
fgi[0] = NI2DIM-1; |
300 |
+ |
ingrid = 0; |
301 |
+ |
} else if (fgi[0] < 0) { |
302 |
+ |
fgi[0] = 0; |
303 |
+ |
ingrid = 0; |
304 |
+ |
} |
305 |
+ |
fgi[1] = (y - ip->smin[1]) * NI2DIM / (ip->smax[1] - ip->smin[1]); |
306 |
+ |
if (fgi[1] >= NI2DIM) { |
307 |
+ |
fgi[1] = NI2DIM-1; |
308 |
+ |
ingrid = 0; |
309 |
+ |
} else if (fgi[1] < 0) { |
310 |
+ |
fgi[1] = 0; |
311 |
+ |
ingrid = 0; |
312 |
+ |
} |
313 |
+ |
return(ingrid); |
314 |
+ |
} |
315 |
+ |
|
316 |
+ |
/* private call to set black flag if not too close to the given sample */ |
317 |
+ |
static void |
318 |
+ |
setblk(INTERP2 *ip, const int i, const int gi[2]) |
319 |
+ |
{ |
320 |
+ |
double dx = (gi[0]+.5)*(1./NI2DIM)*(ip->smax[0] - ip->smin[0]) + |
321 |
+ |
ip->smin[0] - ip->spt[i][0]; |
322 |
+ |
double dy = (gi[1]+.5)*(1./NI2DIM)*(ip->smax[1] - ip->smin[1]) + |
323 |
+ |
ip->smin[1] - ip->spt[i][1]; |
324 |
+ |
|
325 |
+ |
if (dx*dx + dy*dy > 2.*ip->grid2) |
326 |
+ |
ip->da[i].blkflg[gi[1]] |= 1<<gi[0]; |
327 |
+ |
} |
328 |
+ |
|
329 |
+ |
#define chkblk(ip,i,gi) ((ip)->da[i].blkflg[(gi)[1]]>>(gi)[0] & 1) |
330 |
+ |
|
331 |
|
/* Assign full set of normalized weights to interpolate the given position */ |
332 |
|
int |
333 |
|
interp2_weights(float wtv[], INTERP2 *ip, double x, double y) |
334 |
|
{ |
335 |
|
double wnorm; |
336 |
+ |
int fgi[2]; |
337 |
+ |
int ingrid; |
338 |
|
int i; |
339 |
|
|
340 |
< |
if ((wtv == NULL) | (ip == NULL)) |
340 |
> |
if (wtv == NULL) |
341 |
|
return(0); |
342 |
< |
/* need to compute interpolant? */ |
343 |
< |
if (ip->da == NULL && !interp2_analyze(ip)) |
342 |
> |
/* get flag position */ |
343 |
> |
if ((ingrid = interp2_flagpos(fgi, ip, x, y)) < 0) |
344 |
|
return(0); |
345 |
|
|
346 |
|
wnorm = 0; /* compute raw weights */ |
347 |
< |
for (i = ip->ns; i--; ) { |
348 |
< |
double wt = get_wt(ip, i, x, y); |
347 |
> |
for (i = ip->ns; i--; ) |
348 |
> |
if (chkblk(ip, i, fgi)) { |
349 |
> |
wtv[i] = 0; |
350 |
> |
} else { |
351 |
> |
double wt = interp2_wti(ip, i, x, y); |
352 |
|
wtv[i] = wt; |
353 |
|
wnorm += wt; |
354 |
< |
} |
354 |
> |
if (wt <= 1e-9 && ingrid) |
355 |
> |
setblk(ip, i, fgi); |
356 |
> |
} |
357 |
|
if (wnorm <= 0) /* too far from all our samples! */ |
358 |
|
return(0); |
359 |
|
wnorm = 1./wnorm; /* normalize weights */ |
368 |
|
interp2_topsamp(float wt[], int si[], const int n, INTERP2 *ip, double x, double y) |
369 |
|
{ |
370 |
|
int nn = 0; |
371 |
+ |
int fgi[2]; |
372 |
+ |
int ingrid; |
373 |
|
double wnorm; |
374 |
|
int i, j; |
375 |
|
|
376 |
< |
if ((n <= 0) | (wt == NULL) | (si == NULL) | (ip == NULL)) |
376 |
> |
if ((n <= 0) | (wt == NULL) | (si == NULL)) |
377 |
|
return(0); |
378 |
< |
/* need to compute interpolant? */ |
379 |
< |
if (ip->da == NULL && !interp2_analyze(ip)) |
378 |
> |
/* get flag position */ |
379 |
> |
if ((ingrid = interp2_flagpos(fgi, ip, x, y)) < 0) |
380 |
|
return(0); |
381 |
|
/* identify top n weights */ |
382 |
< |
for (i = ip->ns; i--; ) { |
383 |
< |
const double wti = get_wt(ip, i, x, y); |
384 |
< |
if (wti <= 1e-9) |
382 |
> |
for (i = ip->ns; i--; ) |
383 |
> |
if (!chkblk(ip, i, fgi)) { |
384 |
> |
const double wti = interp2_wti(ip, i, x, y); |
385 |
> |
if (wti <= 1e-9) { |
386 |
> |
if (ingrid) |
387 |
> |
setblk(ip, i, fgi); |
388 |
|
continue; |
389 |
+ |
} |
390 |
|
for (j = nn; j > 0; j--) { |
391 |
|
if (wt[j-1] >= wti) |
392 |
|
break; |
400 |
|
si[j] = i; |
401 |
|
nn += (nn < n); |
402 |
|
} |
403 |
< |
} |
403 |
> |
} |
404 |
|
wnorm = 0; /* normalize sample weights */ |
405 |
|
for (j = nn; j--; ) |
406 |
|
wnorm += wt[j]; |