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Add sphere distribution analysis

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PaulStoffregen 2016-02-22 00:45:15 -08:00
commit d2ada0bbe1
1 changed files with 51 additions and 4 deletions
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55
visualize.c
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@ -6,6 +6,47 @@ float soft_iron[9] = {1.0, 0.0, 0.0, 0.0, 1.0, 0.0, 0.0, 0.0, 1.0};
quat_t current_orientation;
// longitude = 0 to 2pi (meaning 0 to 360 degrees)
// latitude = -pi/2 to +pi/2 (meaning -90 to +90 degrees)
// return 0 to 99 - which region on the sphere (100 of equal surface area)
static int sphere_region(float longitude, float latitude)
{
int region;
// https://etna.mcs.kent.edu/vol.25.2006/pp309-327.dir/pp309-327.html
// sphere equations....
// area of unit sphere = 4*pi
// area of unit sphere cap = 2*pi*h h = cap height
// lattitude of unit sphere cap = arcsin(1 - h)
if (latitude > 1.37046f /* 78.52 deg */) {
// arctic cap, 1 region
return 0;
} else if (latitude < -1.37046f /* -78.52 deg */) {
// antarctic cap, 1 region
return 99;
} else if (latitude > 0.74776f /* 42.84 deg */ || latitude < -0.74776f ) {
// temperate zones, 15 regions each
region = floorf(longitude * (float)(15.0 / (M_PI * 2.0)));
if (region < 0) region = 0;
else if (region > 14) region = 14;
if (latitude > 0.0) {
return region + 1; // 1 to 15
} else {
return region + 84; // 84 to 98
}
} else {
// tropic zones, 34 regions each
region = floorf(longitude * (float)(34.0 / (M_PI * 2.0)));
if (region < 0) region = 0;
else if (region > 33) region = 33;
if (latitude >= 0.0) {
return region + 16; // 16 to 49
} else {
return region + 50; // 50 to 83
}
}
}
static void apply_calibration(const magdata_t *in, magdata_t *out)
{
@ -78,9 +119,11 @@ void display_callback(void)
float latitude[MAGBUFFSIZE]; // 0 to PI
float longitude[MAGBUFFSIZE]; // -PI to +PI
float sumx=0.0, sumy=0.0, sumz=0.0, summag=0.0;
int spheredist[100];
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glColor3f(1, 0, 0); // set current color to red
memset(spheredist, 0, sizeof(spheredist));
xscale = 0.06;
yscale = 0.06;
@ -100,9 +143,10 @@ void display_callback(void)
magnitude[i] = sqrtf(point.x * point.x +
point.y * point.y + point.z * point.z);
summag += magnitude[i];
longitude[i] = atan2f(point.y, point.x);
longitude[i] = atan2f(point.y, point.x) + (float)M_PI;
latitude[i] = atan2f(sqrtf(point.x * point.x +
point.y * point.y), point.z);
point.y * point.y), point.z) - (float)(M_PI / 2.0);
spheredist[sphere_region(longitude[i], latitude[i])]++;
count++;
rotate(&point, &draw, rotation);
glPushMatrix();
@ -124,11 +168,14 @@ void display_callback(void)
if (updatenum++ == 500) {
for (i=0; i < MAGBUFFSIZE; i++) {
if (caldata[i].valid) {
printf("long: %6.2f lat: %5.2f\n",
printf("long: %6.2f lat: %6.2f (%.2f)\n",
longitude[i] * 180.0 / M_PI,
latitude[i] * 180.0 / M_PI);
latitude[i] * 180.0 / M_PI, latitude[i]);
}
}
for (i=0; i < 100; i++) {
printf("sphere %d region: %d points\n", 1, spheredist[i]);
}
printf("count = %d\n", count);
printf("sum = %.2f %.2f %.2f\n", sumx, sumy, sumz);
printf("summag = %.2f avg: %.2f\n", summag, summag / (float)count);