1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
|
/************************************************************************************
Filename : Util_MagCalibration.cpp
Content : Procedures for calibrating the magnetometer
Created : April 16, 2013
Authors : Steve LaValle, Andrew Reisse
Copyright : Copyright 2013 Oculus VR, Inc. All Rights reserved.
Use of this software is subject to the terms of the Oculus license
agreement provided at the time of installation or download, or which
otherwise accompanies this software in either electronic or hard copy form.
*************************************************************************************/
#include "Util_MagCalibration.h"
namespace OVR { namespace Util {
void MagCalibration::BeginAutoCalibration(SensorFusion& sf)
{
Stat = Mag_AutoCalibrating;
// This is a "hard" reset of the mag, so need to clear stored values
sf.ClearMagCalibration();
SampleCount = 0;
// reset the statistics
MinMagValues = Vector3f(10000.0f,10000.0f,10000.0f);
MaxMagValues = Vector3f(-10000.0f,-10000.0f,-10000.0f);
MinQuatValues = Quatf(1.0f,1.0f,1.0f,1.0f);
MaxQuatValues = Quatf(0.0f,0.0f,0.0f,0.0f);
}
unsigned MagCalibration::UpdateAutoCalibration(SensorFusion& sf)
{
if (Stat != Mag_AutoCalibrating)
return Stat;
Quatf q = sf.GetOrientation();
Vector3f m = sf.GetMagnetometer();
InsertIfAcceptable(q, m);
if ((SampleCount == 4) && (Stat == Mag_AutoCalibrating))
{
//LogText("Magnetometer Output Spread: %f %f %f\n",MagSpread.x,MagSpread.y,MagSpread.z);
//LogText("Quaternion Spread: %f %f %f %f\n",QuatSpread.x,QuatSpread.y,QuatSpread.z,QuatSpread.w);
SetCalibration(sf);
}
return Stat;
}
void MagCalibration::BeginManualCalibration(SensorFusion& sf)
{
Stat = Mag_ManuallyCalibrating;
sf.ClearMagCalibration();
SampleCount = 0;
}
bool MagCalibration::IsAcceptableSample(const Quatf& q, const Vector3f& m)
{
switch (SampleCount)
{
// Initial sample is always acceptable
case 0:
return true;
break;
case 1:
return (q.DistanceSq(QuatSamples[0]) > MinQuatDistanceSq)&&
((m - MagSamples[0]).LengthSq() > MinMagDistanceSq);
break;
case 2:
return (q.DistanceSq(QuatSamples[0]) > MinQuatDistanceSq)&&
(q.DistanceSq(QuatSamples[1]) > MinQuatDistanceSq)&&
((m - MagSamples[0]).LengthSq() > MinMagDistanceSq)&&
((m - MagSamples[1]).LengthSq() > MinMagDistanceSq);
break;
case 3:
return (q.DistanceSq(QuatSamples[0]) > MinQuatDistanceSq)&&
(q.DistanceSq(QuatSamples[1]) > MinQuatDistanceSq)&&
(q.DistanceSq(QuatSamples[2]) > MinQuatDistanceSq)&&
((PointToPlaneDistance(MagSamples[0],MagSamples[1],MagSamples[2],m) > MinMagDistance)||
(PointToPlaneDistance(MagSamples[1],MagSamples[2],m,MagSamples[0]) > MinMagDistance)||
(PointToPlaneDistance(MagSamples[2],m,MagSamples[0],MagSamples[1]) > MinMagDistance)||
(PointToPlaneDistance(m,MagSamples[0],MagSamples[1],MagSamples[2]) > MinMagDistance));
}
return false;
}
bool MagCalibration::InsertIfAcceptable(const Quatf& q, const Vector3f& m)
{
// Update some statistics
if (m.x < MinMagValues.x)
MinMagValues.x = m.x;
if (m.y < MinMagValues.y)
MinMagValues.y = m.y;
if (m.z < MinMagValues.z)
MinMagValues.z = m.z;
if (m.x > MaxMagValues.x)
MaxMagValues.x = m.x;
if (m.y > MaxMagValues.y)
MaxMagValues.y = m.y;
if (m.z > MaxMagValues.z)
MaxMagValues.z = m.z;
if (q.x < MinQuatValues.x)
MinQuatValues.x = q.x;
if (q.y < MinQuatValues.y)
MinQuatValues.y = q.y;
if (q.z < MinQuatValues.z)
MinQuatValues.z = q.z;
if (q.w < MinQuatValues.w)
MinQuatValues.w = q.w;
if (q.x > MaxQuatValues.x)
MaxQuatValues.x = q.x;
if (q.y > MaxQuatValues.y)
MaxQuatValues.y = q.y;
if (q.z > MaxQuatValues.z)
MaxQuatValues.z = q.z;
if (q.w > MaxQuatValues.w)
MaxQuatValues.w = q.w;
MagSpread = MaxMagValues - MinMagValues;
QuatSpread = MaxQuatValues - MinQuatValues;
if (IsAcceptableSample(q, m))
{
MagSamples[SampleCount] = m;
QuatSamples[SampleCount] = q;
SampleCount++;
return true;
}
return false;
}
Matrix4f MagCalibration::GetMagCalibration() const
{
Matrix4f calMat = Matrix4f();
calMat.M[0][3] = -MagCenter.x;
calMat.M[1][3] = -MagCenter.y;
calMat.M[2][3] = -MagCenter.z;
return calMat;
}
bool MagCalibration::SetCalibration(SensorFusion& sf)
{
if (SampleCount < 4)
return false;
MagCenter = CalculateSphereCenter(MagSamples[0],MagSamples[1],MagSamples[2],MagSamples[3]);
Matrix4f calMat = GetMagCalibration();
sf.SetMagCalibration(calMat);
Stat = Mag_Calibrated;
//LogText("MagCenter: %f %f %f\n",MagCenter.x,MagCenter.y,MagCenter.z);
return true;
}
// Calculate the center of a sphere that passes through p1, p2, p3, p4
Vector3f MagCalibration::CalculateSphereCenter(const Vector3f& p1, const Vector3f& p2,
const Vector3f& p3, const Vector3f& p4)
{
Matrix4f A;
int i;
Vector3f p[4];
p[0] = p1;
p[1] = p2;
p[2] = p3;
p[3] = p4;
for (i = 0; i < 4; i++)
{
A.M[i][0] = p[i].x;
A.M[i][1] = p[i].y;
A.M[i][2] = p[i].z;
A.M[i][3] = 1.0f;
}
float m11 = A.Determinant();
OVR_ASSERT(m11 != 0.0f);
for (i = 0; i < 4; i++)
{
A.M[i][0] = p[i].x*p[i].x + p[i].y*p[i].y + p[i].z*p[i].z;
A.M[i][1] = p[i].y;
A.M[i][2] = p[i].z;
A.M[i][3] = 1.0f;
}
float m12 = A.Determinant();
for (i = 0; i < 4; i++)
{
A.M[i][0] = p[i].x*p[i].x + p[i].y*p[i].y + p[i].z*p[i].z;
A.M[i][1] = p[i].x;
A.M[i][2] = p[i].z;
A.M[i][3] = 1.0f;
}
float m13 = A.Determinant();
for (i = 0; i < 4; i++)
{
A.M[i][0] = p[i].x*p[i].x + p[i].y*p[i].y + p[i].z*p[i].z;
A.M[i][1] = p[i].x;
A.M[i][2] = p[i].y;
A.M[i][3] = 1.0f;
}
float m14 = A.Determinant();
float c = 0.5f / m11;
return Vector3f(c*m12, -c*m13, c*m14);
}
// Distance from p4 to the nearest point on a plane through p1, p2, p3
float MagCalibration::PointToPlaneDistance(const Vector3f& p1, const Vector3f& p2,
const Vector3f& p3, const Vector3f& p4)
{
Vector3f v1 = p1 - p2;
Vector3f v2 = p1 - p3;
Vector3f planeNormal = v1.Cross(v2);
planeNormal.Normalize();
return (fabs((planeNormal * p4) - planeNormal * p1));
}
}}
|
