1 /************************************************************************************

2

3 PublicHeader: OVR.h

4 Filename : OVR_SensorFilter.h

5 Content : Basic filtering of sensor data

6 Created : March 7, 2013

7 Authors : Steve LaValle, Anna Yershova

8

9 Copyright : Copyright 2012 Oculus VR, Inc. All Rights reserved.

10

11 Use of this software is subject to the terms of the Oculus license

12 agreement provided at the time of installation or download, or which

13 otherwise accompanies this software in either electronic or hard copy form.

14

15 *************************************************************************************/

16

17 #ifndef OVR_SensorFilter_h

18 #define OVR_SensorFilter_h

19

20 #include "Kernel/OVR_Math.h"

21

22

23 namespace OVR {

24

25 // This class maintains a sliding window of sensor data taken over time and implements

26 // various simple filters, most of which are linear functions of the data history.

27 class SensorFilter

28 {

29 enum

30 {

31 MaxFilterSize = 100,

32 DefaultFilterSize = 20

33 };

34

35 private:

36 int LastIdx; // The index of the last element that was added to the array

37 int Size; // The window size (number of elements)

38 Vector3f Elements[MaxFilterSize];

39

40 public:

41 // Create a new filter with default size

42 SensorFilter()

43 {

44 LastIdx = -1;

45 Size = DefaultFilterSize;

46 };

47

48 // Create a new filter with size i

49 SensorFilter(int i)

50 {

51 OVR_ASSERT(i <= MaxFilterSize);

52 LastIdx = -1;

53 Size = i;

54 };

55

56

57 // Create a new element to the filter

58 void AddElement (const Vector3f &e)

59 {

60 if (LastIdx == Size - 1)

61 LastIdx = 0;

62 else

63 LastIdx++;

64

65 Elements[LastIdx] = e;

66 };

67

68 // Get element i. 0 is the most recent, 1 is one step ago, 2 is two steps ago, ...

69 Vector3f GetPrev(int i) const

70 {

71 OVR_ASSERT(i >= 0); //

72 int idx = (LastIdx - i);

73 if (idx < 0) // Fix the wraparound case

74 idx += Size;

75 OVR_ASSERT(idx >= 0); // Multiple wraparounds not allowed

76 return Elements[idx];

77 };

78

79 // Simple statistics

80 Vector3f Total() const;

81 Vector3f Mean() const;

82 Vector3f Median() const;

83 Vector3f Variance() const; // The diagonal of covariance matrix

84 Matrix4f Covariance() const;

85 Vector3f PearsonCoefficient() const;

86

87 // A popular family of smoothing filters and smoothed derivatives

88 Vector3f SavitzkyGolaySmooth8() const;

89 Vector3f SavitzkyGolayDerivative4() const;

90 Vector3f SavitzkyGolayDerivative5() const;

91 Vector3f SavitzkyGolayDerivative12() const;

92 Vector3f SavitzkyGolayDerivativeN(int n) const;

93

94 ~SensorFilter() {};

95 };

96

97 } //namespace OVR

98

99 #endif // OVR_SensorFilter_h