| 15 |
|
#define NI2DSMF 0.42f /* minimal smoothing factor */ |
| 16 |
|
|
| 17 |
|
#define NI2DIR (2*4) /* # interpolation directions */ |
| 18 |
+ |
#define NI2DIM 16 /* size of influence map */ |
| 19 |
|
|
| 20 |
|
/* Data structure for interpolant */ |
| 21 |
|
typedef struct { |
| 22 |
|
int ns; /* number of sample positions */ |
| 23 |
|
float dmin; /* minimum diameter (default=1) */ |
| 24 |
|
float smf; /* smoothing factor (def=NI2DSMF) */ |
| 25 |
< |
unsigned short (*da)[NI2DIR]; /* anisotropic distances (private) */ |
| 25 |
> |
float smin[2]; /* sample minima */ |
| 26 |
> |
float smax[2]; /* sample maxima */ |
| 27 |
> |
float grid2; /* grid diameter squared */ |
| 28 |
> |
struct interp2_samp { |
| 29 |
> |
unsigned short dia[NI2DIR]; |
| 30 |
> |
unsigned short infl[NI2DIM]; |
| 31 |
> |
} *da; /* direction array (private) */ |
| 32 |
|
float spt[1][2]; /* sample positions (extends struct) */ |
| 33 |
|
} INTERP2; |
| 34 |
|
|
| 38 |
|
/* Resize interpolation array (caller must assign any new values) */ |
| 39 |
|
extern INTERP2 *interp2_realloc(INTERP2 *ip, int nsamps); |
| 40 |
|
|
| 41 |
+ |
/* Set minimum distance under which samples will start to merge */ |
| 42 |
+ |
extern void interp2_spacing(INTERP2 *ip, double mind); |
| 43 |
+ |
|
| 44 |
+ |
/* Modify smoothing parameter by the given factor */ |
| 45 |
+ |
extern void interp2_smooth(INTERP2 *ip, double sf); |
| 46 |
+ |
|
| 47 |
|
/* Assign full set of normalized weights to interpolate the given location */ |
| 48 |
|
extern int interp2_weights(float wtv[], INTERP2 *ip, double x, double y); |
| 49 |
|
|
| 56 |
|
/* (Re)compute anisotropic basis function interpolant (normally automatic) */ |
| 57 |
|
extern int interp2_analyze(INTERP2 *ip); |
| 58 |
|
|
| 59 |
+ |
/* Compute unnormalized weight for a position relative to a sample */ |
| 60 |
+ |
double interp2_wti(INTERP2 *ip, const int i, double x, double y); |
| 61 |
+ |
|
| 62 |
|
/*************************************************************** |
| 63 |
|
* Typical use is to allocate an INTERP2 struct and assign the |
| 64 |
|
* spt[] array with the ordered sample locations in x & y. (The |
| 68 |
|
* vector for all the samples, or interp2_topsamp() is called to |
| 69 |
|
* get the most important N samples for the specified location. |
| 70 |
|
* The weights (and indexes in the case of interp2_topsamp) |
| 71 |
< |
* are then used as coefficients for corresponding sample values |
| 72 |
< |
* in a vector sum together that interpolates the function at that |
| 73 |
< |
* location. Between the initial allocation call and the first |
| 74 |
< |
* weight evaluation, the dmin member may be adjusted to |
| 75 |
< |
* the distance under which samples will start to merge. If this |
| 76 |
< |
* parameter is later changed, interp2_analyze() should be called |
| 77 |
< |
* to recompute the interpolant. |
| 78 |
< |
* The smf member sets the smoothing factor for interpolation. |
| 79 |
< |
* The default setting of NI2DSMF produces near-optimal |
| 80 |
< |
* interpolation when well-separated sample values are known |
| 81 |
< |
* precisely. If a greater degree of mixing is desired, this |
| 82 |
< |
* paremter may be increased and it will affect the next call |
| 83 |
< |
* to interp2_weights() or interp2_topsamp(). |
| 71 |
> |
* are then used as coefficients for corresponding sample |
| 72 |
> |
* values in a vector sum that interpolates the function at |
| 73 |
> |
* that location. |
| 74 |
> |
* The minimum distance between sample positions defaults to 1.0. |
| 75 |
> |
* Values spaced closer than this will be merged/averaged. |
| 76 |
> |
* The interp2_spacing() call may be used to alter this distance, |
| 77 |
> |
* causing the interpolant to be recalculated during the |
| 78 |
> |
* next call to the sampling functions. |
| 79 |
> |
* The default smoothing factor NI2DSMF provides near-optimal |
| 80 |
> |
* interpolation when well-separated values are known |
| 81 |
> |
* precisely. Increase this setting by a factor > 1 |
| 82 |
> |
* with the interp2_smooth() call if greater mixing is desired. |
| 83 |
> |
* A call of interp2_smooth(ip,0) resets to the minimum |
| 84 |
> |
* default. It is not possible to "sharpen" the data. |
| 85 |
|
**************************************************************/ |
| 86 |
|
|
| 87 |
|
#ifdef __cplusplus |
