| 1 |
greg |
2.6 |
/* RCSid $Id: interp2d.h,v 2.5 2013/02/11 23:33:35 greg Exp $ */ |
| 2 |
greg |
2.1 |
/* |
| 3 |
greg |
2.4 |
* Header for interpolation of anisotropic samples on 2-D plane. |
| 4 |
greg |
2.1 |
* |
| 5 |
|
|
* G.Ward Feb 2013 |
| 6 |
|
|
*/ |
| 7 |
|
|
|
| 8 |
greg |
2.3 |
#ifndef _RAD_INTERP2D_H_ |
| 9 |
|
|
#define _RAD_INTERP2D_H_ |
| 10 |
|
|
|
| 11 |
|
|
#ifdef __cplusplus |
| 12 |
|
|
extern "C" { |
| 13 |
|
|
#endif |
| 14 |
|
|
|
| 15 |
greg |
2.4 |
#define NI2DSMF 0.42f /* minimal smoothing factor */ |
| 16 |
greg |
2.1 |
|
| 17 |
|
|
#define NI2DIR (2*4) /* # interpolation directions */ |
| 18 |
|
|
|
| 19 |
|
|
/* Data structure for interpolant */ |
| 20 |
|
|
typedef struct { |
| 21 |
|
|
int ns; /* number of sample positions */ |
| 22 |
greg |
2.4 |
float dmin; /* minimum diameter (default=1) */ |
| 23 |
greg |
2.1 |
float smf; /* smoothing factor (def=NI2DSMF) */ |
| 24 |
greg |
2.4 |
unsigned short (*da)[NI2DIR]; /* anisotropic distances (private) */ |
| 25 |
greg |
2.1 |
float spt[1][2]; /* sample positions (extends struct) */ |
| 26 |
|
|
} INTERP2; |
| 27 |
|
|
|
| 28 |
|
|
/* Allocate a new set of interpolation samples (caller assigns spt[] array) */ |
| 29 |
|
|
extern INTERP2 *interp2_alloc(int nsamps); |
| 30 |
|
|
|
| 31 |
greg |
2.2 |
/* Resize interpolation array (caller must assign any new values) */ |
| 32 |
|
|
extern INTERP2 *interp2_realloc(INTERP2 *ip, int nsamps); |
| 33 |
|
|
|
| 34 |
greg |
2.5 |
/* Set minimum distance under which samples will start to merge */ |
| 35 |
|
|
extern void interp2_spacing(INTERP2 *ip, double mind); |
| 36 |
|
|
|
| 37 |
|
|
/* Modify smoothing parameter by the given factor */ |
| 38 |
|
|
extern void interp2_smooth(INTERP2 *ip, double sf); |
| 39 |
|
|
|
| 40 |
greg |
2.1 |
/* Assign full set of normalized weights to interpolate the given location */ |
| 41 |
|
|
extern int interp2_weights(float wtv[], INTERP2 *ip, double x, double y); |
| 42 |
|
|
|
| 43 |
|
|
/* Get normalized weights and indexes for n best samples in descending order */ |
| 44 |
|
|
extern int interp2_topsamp(float wt[], int si[], const int n, |
| 45 |
|
|
INTERP2 *ip, double x, double y); |
| 46 |
|
|
/* Free interpolant */ |
| 47 |
|
|
extern void interp2_free(INTERP2 *ip); |
| 48 |
greg |
2.2 |
|
| 49 |
|
|
/* (Re)compute anisotropic basis function interpolant (normally automatic) */ |
| 50 |
|
|
extern int interp2_analyze(INTERP2 *ip); |
| 51 |
greg |
2.3 |
|
| 52 |
greg |
2.4 |
/*************************************************************** |
| 53 |
|
|
* Typical use is to allocate an INTERP2 struct and assign the |
| 54 |
|
|
* spt[] array with the ordered sample locations in x & y. (The |
| 55 |
|
|
* actual orientation of the axes is not important so long as |
| 56 |
|
|
* the application is consistent.) During interpolation, either |
| 57 |
|
|
* interp2_weights() is called to obtain a normalized weighting |
| 58 |
|
|
* vector for all the samples, or interp2_topsamp() is called to |
| 59 |
|
|
* get the most important N samples for the specified location. |
| 60 |
|
|
* The weights (and indexes in the case of interp2_topsamp) |
| 61 |
greg |
2.6 |
* are then used as coefficients for corresponding sample |
| 62 |
|
|
* values in a vector sum that interpolates the function at |
| 63 |
|
|
* that location. |
| 64 |
greg |
2.5 |
* The minimum distance between sample positions defaults to 1.0. |
| 65 |
greg |
2.6 |
* Values spaced closer than this will be merged/averaged. |
| 66 |
|
|
* The interp2_spacing() call may be used to alter this distance, |
| 67 |
greg |
2.5 |
* causing the interpolant to be recalculated during the |
| 68 |
greg |
2.6 |
* next call to the sampling functions. |
| 69 |
greg |
2.5 |
* The default smoothing factor NI2DSMF provides near-optimal |
| 70 |
|
|
* interpolation when well-separated values are known |
| 71 |
greg |
2.6 |
* precisely. Increase this setting by a factor > 1 |
| 72 |
greg |
2.5 |
* with the interp2_smooth() call if greater mixing is desired. |
| 73 |
greg |
2.6 |
* A call of interp2_smooth(ip,0) resets to the minimum |
| 74 |
greg |
2.5 |
* default. It is not possible to "sharpen" the data. |
| 75 |
greg |
2.4 |
**************************************************************/ |
| 76 |
|
|
|
| 77 |
greg |
2.3 |
#ifdef __cplusplus |
| 78 |
|
|
} |
| 79 |
|
|
#endif |
| 80 |
|
|
#endif /* !_RAD_INTERP2D_H_ */ |
