radar

Radar_NoData, Radar_ValIsNoData, Radar_ValIsData, Radar_ErrMsgAppend, Radar_ErrMsgGet, Radar_SwapOn, Radar_SwapOff, Radar_ToggleSwap, Radar_GetSINT16, Radar_GetUINT16, Radar_GetSINT32, Radar_GetUINT32, Radar_GetFLOAT32, Radar_SwapArr16, Radar_AllocArr3, Radar_FreeArr3, Radar_AllocArr4, Radar_FreeArr4, Radar_GrndRng, Radar_RayRng, Radar_ArrSearch, Radar_AzArrSearch, Radar_BilinInterp, Radar_PolarDataInit, Radar_PolarDataSetAlloc, Radar_PolarDataFree, − radar data functions.

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#include <radar.h>

float Radar_NoData(void);
int Radar_ValIsNoData(float v);
int Radar_ValIsData(float v);

void Radar_ErrMsgAppend(char *msg);
char *Radar_ErrMsgGet(void);

void Radar_SwapOn(void);
void Radar_SwapOff(void);
void Radar_ToggleSwap(void);
int Radar_GetSINT16(char *b);
unsigned Radar_GetUINT16(char *b);
int Radar_GetSINT32(char *b);
unsigned Radar_GetUINT32(char *b);
double Radar_GetFLOAT32(char *b);
void Radar_SwapArr16(unsigned short *r, size_t nw);
float *** Radar_AllocArr3(unsigned i, unsigned j, unsigned k);
void Radar_FreeArr3(float ***d);
float **** Radar_AllocArr4(unsigned i, unsigned j, unsigned k);
void Radar_FreeArr4(float ****d);

double Radar_GrndRng(double d, double h, Angle tilt);
double Radar_RayRng(double d, double h, Angle tilt);

int Radar_ArrSearch(float *xx, int n, float x);
int Radar_AzArrSearch(Angle *xx, int n, Angle x);
float Radar_BilinInterp(Angle *az0, float *r0, float **z0, Angle az1, float r1);

void Radar_PolarDataInit(struct Radar_PolarData *rpdPtr);
int Radar_PolarDataSetAlloc(struct Radar_PolarData *rpdPtr, GeoPt ctr, unsigned n_az, unsigned n_rng);
void Radar_PolarDataFree(struct Radar_PolarData *rpdPtr);

These utility functions are used by other functions that access and manipulate radar data.

Radar_NoData returns a value that indicates unusable data.

Radar_ValIsNoData returns true if v equals this value. Radar_ValIsData returns false if v is not this value, i.e. if v is usable data.

Radar_ErrMsgAppend appends msg to an internal error string.

Radar_ErrMsgGet returns this string and resets it to "". The return value should not be modified by the user.

The Radar_Get functions access integers, applying byte swapping if necessary.

Radar_SwapOn switches byte swapping on.

Radar_SwapOff switches byte swapping off.

Radar_ToggleSwap switches byte swapping on if it is off, or vice versa.

Radar_GetSINT16 retrieves a signed 16 bit integer from address

b, applying byte swapping if necessary (as indicated by previous calls to Radar_ToggleSwap).

Radar_GetUINT16 retrieves an unsigned 16 bit integer from

address b, applying byte swapping if necessary.

Radar_GetSINT32 retrieves a signed 32 bit integer from

address b, applying byte swapping if necessary.

Radar_GetUINT32 retrieves an unsigned 32 bit integer from address

b, applying byte swapping if necessary.

Radar_GetFLOAT32 retrieves a 32 bit floating point value from address

b, applying byte swapping if necessary.

Radar_SwapArr16 swaps nw pairs of bytes at address *r if

directed to by previous calls to Radar_ToggleSwap. Otherwise it does nothing.

Radar_AllocArr3 returns a dynamically allocated array dimensioned

[i][j][k], or NULL if allocation fails. The memory should be freed by handing the return value to Radar_FreeArr3.

Radar_AllocArr4 returns a dynamically allocated array dimensioned

[i][j][k][l], or NULL if allocation fails. The memory should be freed by handing the return value to Radar_FreeArr3.

Radar_GrndRng returns the distance along the ground to the point below

a cell at distance d meters along a ray elevated to tilt degrees. Radar antenna is h meters above ground. Return value is in meters.

Radar_RayRng returns the distance along a ray elevated to tilt

degrees to a cell above a point d meters from the radar. Radar antenna is h meters above ground. Return value is in meters.

Radar_ArrSearch searches monotonic array xx of length n for

an interval containing x. If it finds one, it returns the index of the lower boundary. If x is out of bounds, the function returns -1. Radar_AzArrSearch behaves like Radar_ArrSearch except the input array and sought for value are angles. Zero crossings are handled correctly.

Radar_BilinInterp returns the value for a field at azimuth az

and range r from a radar, given bounding azimuths in az_g[2] and bounding ranges in r_g[2], and corner values in z[2][2]. It uses bilinear interpolation.

The Radar_PolarData functions access polar data stored in structures

declared as:

struct Radar_PolarData {
    GeoPt ctr;
    unsigned n_az;
    Angle *az;
    unsigned n_rng;
    float *rng;
    float **dat;
};

Radar_PolarDataInit initializes the polar data structure at rpdPtr with bogus values. rpdPtr is assumed to contain bogus values.

Radar_PolarDataSetAlloc sets the origin of the polar data structure at rpdPtr to ctr, and allocates the grid and data arrays to store data for n_az azimuths and n_rng range values.

Radar_PolarDataFree frees internal storage associated with rpdPtr. The structure itself remains allocated. rpdPtr is re-initialized with bogus values.

radar data

Gordon Carrie (user0 at tkgeomap.org)