Compression of surface normals in three-dimensional graphics data

• US 6,603,470 B1
• Filed: 11/04/1997
• Issued: 08/05/2003
• Est. Priority Date: 08/04/1995
• Status: Expired due to Term

• Current Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Original Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Inventors: Deering, Michael F.
• Primary Examiner(s): Nguyen, Phu K.
• Application Number:
  US08/963,863
• Time in Patent Office: 2,100 Days
• Field of Search: 345/418-20, 345/433, 345/427, 345/428
• US Class Current: 345/419
• CPC Class Codes: G06T 9/001 Model-based coding, e.g. wire frame

Abstract

A system and method for compression of surface normals in three-dimensional graphics data. The method comprises compressing a normal by identifying the location of a first point located at the intersection of the surface of a predetermined sphere (centered on the origin of a set of x-y-z axes) and a vector extended from the origin in a direction specified by the coordinate values of the normal. Identification of the first point includes specifying an index value and one or mapping values. The index value is usable during decompression to identify a second point on the sphere from a plurality of points in a predetermined surface region (such as a predetermined sextant of a predetermined octant region). In one embodiment, the index includes a θ component and a φ component which are usable to locate the second point. The θ component value is measured about the y axis to the second point while the φ component value is measured latitudinally from a plane defined by y=0 to the second point. The one or more mapping values include a sextant value which translates the second point to a third point by performing foldings about the planes x=y, y=z, and x=z within the predetermined octant. The one or more mapping values also include an octant value which is usable to locate the first point from the third point by identifying one or more sign bits of the fist point. Delta-encoding of normals is also disclosed.

Claims

1. A computer-implemented method for compressing three-dimensional graphics data including a first three-dimensional surface normal corresponding to a three-dimensional graphics object, said method comprising:

receiving first three-dimensional surface normal data which represents said first surface normal,

compressing said first three-dimensional surface normal data into a first number of bits by;

generating a first subset of said first number of bits to indicate which one of a first plurality of subsets of all possible three-dimensional normals includes said first three-dimensional surface normal, wherein said compressing produces compressed first surface normal data; and

storing said compressed first surface normal data.

2. The method of claim 1, further comprising generating a second subset of said first number of bits to indicate which one of a second plurality of subsets includes said first surface normal, wherein said second plurality of subsets consist of all possible three-dimensional normals in the subset indicated by said first plurality of bits.

3. The method of claim 2, further comprising generating a third subset of said first number of bits to indicate which one of a plurality of three-dimensional normals encoded in a table correspond most closely to said first three-dimensional surface normal, wherein said plurality of three-dimensional surface normals are within said indicated second subset.

4. The method of claim 2, wherein said second plurality of subsets are symmetrical.

5. The method of claim 2, wherein said second plurality of subsets are symmetrical and contiguous.

6. The method of claim 2, wherein each of said second plurality of subsets represents a sextant of an octant, wherein said octant corresponds to the indicated one of the first plurality of subsets.

7. The method of claim 1, wherein each of said first plurality of subsets is an octant of a surface of a sphere representing all possible normalized three-dimensional surface normals, wherein said first surface normal is normalized.

8. The method of claim 1, wherein each of said first plurality of subsets represents a sextant of a sphere representing all possible three-dimensional surface normals.

9. The method of claim 1, wherein said storing said compressed first surface normal data includes storing said compressed first surface normal data in a memory, wherein said compressed first surface normal data requires reduced memory space as compared to said first surface normal data.

10. The method of claim 1, further comprising transmitting said compressed first surface normal data across a network.

11. The method of claim 1, wherein said graphical object includes one or more geometric primitives, and wherein said fast surface normal corresponds to one of said one or more geometric primitives.

12. The method of claim 1, wherein said graphical object includes one or more geometric primitives each including one or more vertices, wherein said first surface normal corresponds to one of said one or more vertices of said one or more geometric primitives.

13. The method of claim 1, wherein said first plurality of subsets of all possible three-dimensional normals are symmetrical.

14. The method of claim 1, wherein said first plurality of subsets of all possible three-dimensional normals are contiguous.

15. The method of claim 1, wherein said second plurality of subsets are contiguous.

16. The method of claim 1, further comprising selecting a second subset of said first number of bits to indicate which one of a plurality of three-dimensional normals encoded in a table correspond most closely to said first three-dimensional surface normal, wherein said plurality of three-dimensional surface normals are within said selected second subset.

17. The method of claim 1, wherein said first plurality of subsets are symmetrical and contiguous.

18. The method of claim 1, further comprising:

encoding an index value, wherein said index value is usable to select a particular set of coordinate magnitude values from a predetermined plurality of sets of coordinate magnitude values within said indicated first subset.

19. The method of claim 1, wherein said storing comprises storing said compressed first surface normal data on a computer-readable medium.

20. The method of claim 1, wherein said first surface normal data includes x, y, and z components.

21. The method of claim 1, further comprising:

receiving second surface normal data which represents a second three-dimensional surface normal;

compressing said second surface normal data by delta-encoding said second surface normal data relative to said first surface normal data, wherein said compressing said second surface normal data produces compressed second surface normal data;

storing said compressed second surface normal data.

22. The method of claim 21, wherein said compressing said second surface normal data includes delta-encoding each of a plurality of component values with respect to a corresponding plurality of component values for said first surface normal data.

23. The method of claim 22, wherein said compressing said second surface normal data includes quantizing each of said plurality of delta-encoded component values to a lesser number of bits.

24. The method of claim 23, wherein compressing said second surface normal data further includes perfonming a variable-length encoding of each of said quantized plurality of delta-encoded component values.

25. The method of claim 1, further comprising:

receiving second three-dimensional surface normal data which represents a second surface normal;

compressing said second surface normal data by generating a delta angle θ

value and a delta angle φ

value, wherein said delta angle θ

value is delta-encoded with respect to an angle θ

that corresponds to said first surface normal, and wherein said delta angle φ

value is delta-encoded with respect to an angle φ

that corresponds to said first surface normal, and wherein said compressing said second surface normal data produces compressed second surface normal data; and

storing said compressed second surface normal data.

26. The method of claim 25, wherein said compressing said second surface normal data includes quantizing said delta angle φ

value and said delta angle θ

value to a lesser number of bits.

27. The method of claim 26, wherein compressing said second surface normal data further includes performing a variable-length encoding of said quantized delta angle φ

value and said quantized delta angle θ

value.

28. A computer-implemented method for compressing a first three-dimensional surface normal corresponding to a graphical object, the method comprising:

receiving first surface normal data which represents the first surface normal;

compressing said first three-dimensional surface normal data into a first number of bits by;

selecting a first subset of said first number of bits to indicate which one of a first plurality of subsets of all possible three-dimensional normals includes said first three-dimensional surface normal, wherein said wherein said compressing produces compressed first surface normal data; and

transferring said compressed first surface normal data.

29. The method of claim 28, wherein said compressed first surface normal data is usable to generate decompressed normal data corresponding to said first surface normal data.

30. The method of claim 29, wherein said decompressed normal data substantially approximates said flat surface normal data.

31. The method of claim 28, wherein said fist surface normal is usable in rendering said graphical object on a display.

32. The method of claim 28, wherein said compressing said first surface normal data includes utilizing geometric characteristics of said first surface normal.

33. The method of claim 28, wherein said compressing said first surface normal data includes encoding information identifying a location of a first point on a surface of a predetermined sphere.

34. The method of claim 33, wherein said predetermined sphere is centered on an origin of a first set of coordinate axes which define a first coordinate space, and wherein said first surface normal data includes a first set of coordinate values.

35. The method of claim 34, wherein an intersection of said surface of said predetermined sphere and a vector extending from said origin of said first set of coordinate axes in a direction specified by said first set of coordinate values substantially approximates said location of said first point.

36. The method of claim 34, wherein said location of said first point on said surface of said predetermined sphere corresponds to said first set of coordinate values.

37. The method of claim 36, wherein said encoding information identifying said location of said first point includes:

encoding an index value usable to select an intermediate set of coordinate magnitude values from a predetermined plurality of sets of coordinate magnitude values.

38. The method of claim 37, wherein said predetermined plurality of sets of coordinate magnitude values correspond to predetermined points within a predetermined sextant of a predetermined octant of said predetermined sphere, and wherein said intermediate set of coordinate magnitude values corresponds to a second point within said predetermined sextant of said predetermined octant.

39. The method of claim 37, wherein said encoding information identifying said location of said first point includes:

encoding a sextant value usable to generate a final set of coordinate magnitudes values which correspond to magnitudes of said first set of coordinate values.

40. The method of claim 39, wherein said intermediate set of coordinate magnitude values correspond to a second point within said predetermined sextant of said predetermined octant;

and wherein said sextant value specifies a first sextant within said predetermined octant of said predetermined sphere, and wherein said sextant value is usable to generate magnitudes of said first set of coordinate values from said intermediate set of coordinate magnitude values by mapping said second point to a third point within said first sextant.

41. The method of claim 37, wherein said encoding information identifying said location of said first point includes:

encoding an octant value usable to represent one or more sign bits of said first set of coordinate values.

42. A computer-implemented method for compressing a first surface normal corresponding to a graphical object, comprising:

receiving first surface normal data representing said first surface normal;

compressing said first surface normal data by encoding information identifying a location of a first point on a surface of a predetermined sphere, wherein said compressing includes generating an index value and one or more mapping values;

storing said index value and said one or more mapping values;

wherein said index value is usable to select a fist set of intermediate surface normal data from a plurality of sets of intermediate surface normal data;

and wherein said one or more mapping values are usable to generate decompressed surface normal data from said intermediate surface normal data.

43. The method of claim 42, wherein said first surface normal is usable in rendering said graphical object on a display.

44. The method of claim 42, wherein said graphical object includes one or more geometric primitives, and wherein said first surface normal corresponds to one of said one or more geometric primitives.

45. The method of claim 42, wherein said predetermined sphere is centered on an origin of a first set of coordinate axes which define a first coordinate space, and wherein said first surface normal data includes a first set of coordinate values.

46. The method of claim 45, wherein an intersection of said surface of said predetermined sphere and a vector extending from said origin of said first set of coordinate axes in a direction specified by said first set of coordinate values substantially approximates said location of said first point.

47. The method of claim 45, wherein said location of said first point on said surface of said predetermined sphere corresponds to said fist set of coordinate values.

48. The method of claim 47, wherein said plurality of sets of intermediate surface normal data includes a plurality of sets of coordinate values, wherein said plurality of sets of coordinate values correspond to a plurality of points located within a predetermined surface region of said predetermined sphere.

49. The method of claim 48, wherein said first set of intermediate surface normal data includes an intermediate set of coordinate values identifying a second point included in said plurality of points.

50. The method of claim 49, wherein said decompressed surface normal data includes a final set of coordinate values substantially equal to said first set of coordinate values.

51. The method of claim 50, wherein said one or more mapping values include a first mapping value and a second mapping value.

52. The method of claim 51, wherein said first mapping value specifies a permutation of coordinate values within said intermediate set of coordinate values usable to generate magnitudes of said final set of coordinate values.

53. The method of claim 52, wherein said second mapping value specifies one or more sign bits of said final set of coordinate values.

54. The method of claim 51, wherein said first coordinate space is an xyz coordinate space, said first set of coordinate axes includes an x axis, a y axis, and a z axis, said first set of coordinate values includes an x coordinate component, a y coordinate component, and a z coordinate component, and wherein said predetermined surface region is a predetermined sextant region of a predetermined octant region.

55. The method of claim 54, wherein said first mapping value is a sextant value representative of one of six sextant regions of said predetermined octant region, wherein said sextant value is usable to permute magnitudes of said x coordinate component, said y coordinate component, and said z coordinate component in order to generate magnitudes of said final set of coordinate values.

56. The method of claim 55, wherein said second mapping value is an octant value specifying a first octant region of said predetermined sphere, wherein said octant value is usable to generate one or more sign bits of said final set of coordinate values.

57. The method of claim 56, wherein said one or more sign bits of said final set of coordinate values correspond to sign bits of points located within said first octant region of said predetermined sphere.

58. The method of claim 54, wherein said first mapping value is a sextant value representative of a first sextant region of said predetermined octant region, wherein said sextant value specifies performing foldings about the planes x=y, y=z, and x=z in order to generate magnitudes of said final set of coordinate values.

59. The method of claim 49, wherein said index value includes a plurality of index component values usable to locate said second point within said predetermined surface region of said predetermined sphere.

60. The method of claim 59, wherein said plurality of index component values includes a first angular index component and a second angular index component, wherein said first angular index component is a latitude value of said second point within said predetermined surface region, and wherein said second angular index component is a longitude value of said second point within said predetermined surface region.

61. A computer-implemented method for compressing a first three-dimensional surface normal corresponding to a graphical object, comprising:

receiving first three-dimensional surface normal data representing said first surface normal;

compressing said first surface normal data by encoding information identifying a location of a first point on a surface of a predetermined sphere, wherein said surface of said predetermined sphere represents all possible normalized three-dimensional surface normals wherein said compressing includes generating an index value and one or more mapping values;

transferring said index value and said one or more mapping values;

wherein said index value is usable to select a first set of intermediate surface normal data from a plurality of sets of intermediate surface normal data;

and wherein said one or more mapping values are usable to generate decompressed surface normal data from said intermediate surface normal data.

62. A computer-implemented method for compressing a first three-dimensional surface normal corresponding to a graphical object, comprising:

generating data representing a plurality of points located on a surface of a predetermined sphere, wherein said surface of said sphere represents all possible three-dimensional surface normals;

storing data representing a subset of said plurality of points in a normal look-up table;

receiving first surface normal data which represents said first surface normal;

compressing said first surface normal data by encoding an index value and one or more mapping values;

storing said index value and said one or more mapping values;

wherein said index value is usable to select intermediate surface normal data from said data representing said subset of said plurality of points stored in said normal look-up table;

and wherein said one or mapping values are usable to generate decompressed surface normal data from said intermediate surface normal data.

63. The method of claim 62, wherein said subset of said plurality of points are located in a predetermined surface region of said predetermined sphere, wherein said predetermined surface region represents a subset of all possible three-dimensional surface normals.

64. The method of claim 63, wherein said data representing said subset of said plurality of points includes coordinate values for each of said subset of said plurality of points.

65. The method of claim 63, wherein said first surface normal data includes a first set of coordinate values.

66. The method of claim 64, wherein said intermediate surface normal data includes an intermediate set of coordinate values.

67. The method of claim 65, wherein said decompressed surface normal data includes a final set of coordinate values substantially equal to said first set of coordinate values.

68. The method of claim 66, wherein said predetermined surface region is a predetermined sextant region of a predetermined octant region of said predetermined sphere.

69. The method of claim 68, wherein said index value includes a plurality of index component values usable to specify locations of points within said predetermined surface region.

70. The method of claim 69, wherein said plurality of index component values includes a first angular index component and a second angular index component wherein said first angular index component is a latitude value of said second point within said predetermined surface region, and wherein said second angular index component is a longitude value of said second point within said predetermined surface region.

71. The method of claim 69, wherein said one or more mapping values include a sextant value representative of one of six sextant regions of said predetermined octant region, wherein said sextant value is usable to permute magnitudes of said x coordinate component, said y coordinate component, and said z coordinate component in order to generate magnitudes of said final set of coordinate values.

72. The method of claim 71, wherein said fist mapping value is a sextant value representative of a first sextant region of said predetermined octant region, wherein said sextant value specifies performing folding about the planes x=y, y=z, and x=z in order to generate magnitudes of said final set of coordinate values.

73. The method of claim 72, wherein said one or more mapping values include an octant value specifying a first octant region of said predetermined sphere, wherein said octant value is usable to generate one or more sign bits of said final set of coordinate values.

74. The method of claim 62, wherein said first surface normal is usable in rendering said graphical object on a display.

75. The method of claim 62, wherein said predetermined sphere is centered on an origin of a first set of coordinate axes which define a first coordinate space, and wherein said first surface normal data includes a first set of coordinate values.

76. The method of claim 75, wherein said location of said first point on said surface of said predetermined sphere corresponds to said first set of coordinate values.

77. A system for compressing a first three-dimensional surface normal corresponding to a graphical object, comprising:

a memory configured to store first surface normal data representing said first surface normal;

a processor coupled to said memory, wherein said processor is configured to compress said first surface normal data by utilizing characteristics of said first surface normal, thereby producing compressed first surface normal data, wherein said processor is configured to compress said first three-dimensional surface normal data into a first number of bits by generating a first subset of said first number of bits to indicate which one of a first plurality of subsets of all possible three-dimensional normals includes said first three-dimensional surface normal, wherein said compressing produces compressed first surface normal data, wherein said processor is configured to store said compressed first surface normal data in said memory.

78. The system of claim 77, wherein said compressed first surface normal data is usable to generate decompressed normal data corresponding to said first surface normal data.

79. The system of claim 78, wherein said decompressed normal data substantially approximates said first surface normal data.

80. The system of claim 77, wherein said decompressed normal data comprises said first surface normal data.

81. The system of claim 77, further comprising a display, wherein said first surface normal is usable in rendering said graphical object on said display.

82. The system of claim 77, wherein said first surface normal data comprises a first act of coordinate values, and wherein said compressed first surface normal data is usable to generate a decompressed set of coordinate values corresponding to said first set of coordinate values.

83. The system of claim 77, wherein said graphical object includes one or more geometric primitives, and wherein said first surface normal corresponds to one of said one or more geometric primitives.

84. The system of claim 77, wherein said graphical object includes one or more geometric primitives each including one or more vertices, wherein said first surface normal corresponds to one of said one or more vertices of said one or more geometric primitives.

85. The system of claim 77, wherein said processor is configured to utilize geometric characteristics of said first surface normal in order to compress said first surface normal data.

86. A system for compressing a first three-dimensional surface normal corresponding to a graphical object, comprising:

a processor coupled to receive first surface normal data corresponding to said first surface normal, wherein said processor is configured to compress said first surface normal data by utilizing characteristics of said first surface normal, wherein said processor is configured to compress said first three-dimensional surface normal data into a first number of bits by generating a first subset of said first number of bits to indicate which one of a first plurality of subsets of all possible three-dimensional normals includes said first three-dimensional surface normal, wherein said compressing produces compressed first surface normal data, thereby producing compressed first surface normal data, and wherein said processor is configured to transfer said compressed first surface normal data.

87. The system of claim 86, wherein said compressed first surface normal data is usable to generate decompressed normal data corresponding to said first surface normal data.

88. The system of claim 87, wherein said decompressed normal data substantially approximates said first surface normal data.

89. The system of claim 86, wherein said processor is configured to utilize geometric characteristics of said first surface normal in order to compress said first surface normal data.

90. A system for compressing a first three-dimensional surface normal corresponding to a graphical object, comprising:

a memory configured to store first surface normal data representing said first surface normal;

a processor coupled to said memory, wherein said processor is configured to compress said first surface normal data by utilizing characteristics of said first surface normal, thereby producing compressed first surface normal data, wherein said processor is configured to compress said first three-dimensional surface normal data into a first number of bits by generating a first subset of said first number of bits to indicate which one of a first plurality of subsets of all possible three-dimensional normals includes said first three-dimensional surface normal, wherein said compressing produces compressed first surface normal data, wherein said processor is configured to store said compressed first surface normal data in said memory;

wherein said processor is configured to delta-encode said compressed first surface normal data with respect to previously specified normal data.

91. The system of claim 90, wherein said compressing said first surface normal data includes utilizing geometric characteristics of said first surface normal.

92. A system for compressing a first three-dimensional surface normal corresponding to a graphical object, comprising:

a memory configured to store first surface normal data representing said first surface normal;

a processor coupled to said memory, wherein said processor is configured to compress said first surface normal data by encoding information identifying a location of a first point on a surface of a predetermined sphere, wherein said surface of said predetermined sphere represents all possible three-dimensional surface normals, wherein said compressing produces compressed first surface normal data, wherein said processor is configured to store said compressed first surface normal data in said memory.

93. The system of claim 92, wherein said predetermined sphere is centered on an origin of a first set of coordinate axes which define a first coordinate space, and wherein said first surface normal data includes a first set of coordinate values.

94. The system of claim 93, wherein an intersection of said surface of said predetermined sphere and a vector extending from said origin of said first set of coordinate axes in a direction specified by said fist set of coordinate values substantially approximates said location of said first point.

95. The system of claim 93, wherein said location of said first point on said surface of said predetermined sphere corresponds to said first set of coordinate values.

96. The system of claim 95, wherein said information identifying said location of said first point includes an index value and one or more mapping values.

97. The system of claim 96, wherein said index value is usable to select a first set of intermediate surface normal data from a plurality of sets of intermediate surface normal data.

98. The system of claim 97, wherein said one or more mapping values are usable to generate decompressed surface normal data from said first set of intermediate surface normal data.

99. The system of claim 97, wherein said plurality of sets of intermediate surface normal data are a plurality of sets of coordinate values corresponding to a plurality of points located in a predetermined surface region of said predetermined sphere, and wherein said first set of intermediate surface normal data is a first set of intermediate coordinate values corresponding to a second point in said predetermined surface region.

100. The system of claim 99, wherein said one or more mapping values are usable to generate a final set of coordinate values from said first set of intermediate coordinate values, wherein said final set of coordinate values are approximately equal to said first set of coordinate values.

101. The system of claim 100, wherein said one or more mapping values include a first mapping value and a second mapping value.

102. The system of claim 101 wherein said first mapping value specifies a permutation of coordinate magnitude values within said first set of intermediate coordinate values usable to generate magnitudes of said final set of coordinate values.

103. The system of claim 102, wherein said second mapping value specifies one or more sign bits of said final set of coordinate values.

104. The system of claim 101, wherein said predetermined surface region is a predetermined sextant region of a predetermined octant region.

105. The system of claim 104, wherein said first mapping value is a sextant value specifying a first sextant within said predetermined octant region, wherein said sextant value is usable to permute an order of said intermediate coordinate magnitude values in order to generate magnitudes of said final set of coordinate values.

106. The system of claim 105, wherein said second mapping value is an octant value specifying a first octant of said predetermined sphere, wherein said octant value is usable to specify one or more sign bits of said final set of coordinate values.

107. The system of claim 99, wherein said index value includes a plurality of index component values usable to specify a location of said second point within said predetermined surface region.

108. The system of claim 107, wherein said plurality of index component values includes a first angular index component and a second angular index component, wherein said first angular index component is a latitude value of said second point within said predetermined surface region, and wherein said second angular index component is a longitude value of said second point within said predetermined surface region.

109. A memory media which stores program instructions for compressing a first surface normal corresponding to a graphical object, wherein said program instructions are executable to implement the steps of:

receiving first surface normal data which represents said first surface normal;

compressing said first three-dimensional surface normal data into a first number of bits by;

selecting a first subset of said first number of bits to indicate which one of a first plurality of symmetrical subsets of all possible three-dimensional normals includes said first three-dimensional surface normal, wherein said compressing produces compressed first surface normal data; and

storing said compressed first surface normal data.

110. The memory media of claim 109, wherein said compressing said first surface normal data includes utilizing geometric characteristics of said first surface normal.

111. The memory media of claim 109, wherein said compressing includes delta-encoding said first surface normal data relative to previously specified surface normal data.

112. A memory media which stores program instructions for compressing a three-dimensional first surface normal corresponding to a graphical object, wherein said program instructions are executable to implement the steps of:

receiving first three-dimensional surface normal data which represents said first surface normal;

compressing said first surface normal data into a first number of bits by;

selecting a first subset of said first number of bits to indicate which one of a first plurality of symmetrical subsets of all possible three-dimensional normals includes said first three-dimensional surface normal, wherein said compressing produces compressed first surface normal data; and

transferring said compressed first surface normal data.

113. The memory media of claim 112, wherein said compressing sad first surface normal data includes utilizing geometric characteristics of said first surface normal.

114. The memory media of claim 112, wherein said compressing said first surface normal data includes encoding information identifying a location of a first point on a surface of a predetermined sphere, wherein said surface of said predetermined sphere represents all possible normalized three-dimensional normals.

115. A memory media which stores program instructions for compressing a first three-dimensional surface normal corresponding to a graphical object, wherein said program instructions are executable to implement the steps of:

receiving first three-dimensional surface normal data which represents said first three-dimensional surface normal;

compressing said first surface normal data by encoding information identifying a location of a first point on a surface of a predetermined sphere, wherein said surface of said sphere represents all possible three-dimensional surface normals, wherein said compressing produces compressed first surface normal data;

storing said compressed first surface normal data.

116. The memory media of claim 115, wherein said predetermined sphere is centered on an origin of a first set of coordinate axes which define a first coordinate space, and wherein said first surface normal data includes a first set of coordinate values.

117. The memory media of claim 115, wherein said information identifying said location of said first point includes an index value and one or more mapping values.

118. The memory media of claim 117, wherein said index value is usable to select an intermediate set of coordinate values from a plurality of predetermined sets of coordinate values, wherein said plurality of predetermined sets of coordinate values correspond to points located in a predetermined surface region of said predetermined sphere, and wherein said intermediate set of coordinate values corresponds to a second point located within said predetermined surface region.

119. The memory media of claim 118, wherein said index value includes a plurality of index component values, wherein each of plurality of index component values is indicative of an angular value usable to determine said location of said first point within said predetermined surface region of said predetermined sphere.

120. The memory media of claim 119, wherein said plurality of index component values includes a first angular index component and a second angular index component, wherein said first angular index component is a latitude value of said second point within said predetermined surface region, and wherein said second angular index component is a longitude value of said second point within said predetermined surface region.

121. The memory media of claim 118, wherein said one or more mapping values are usable to map said intermediate set of coordinate values to a final set of coordinate values, wherein said final set of coordinate values are substantially equal to said first set of coordinate values.

122. The memory media of claim 121, wherein said predetermined surface region is a predetermined sextant region of a predetermined octant region of said surface of said predetermined sphere.

123. The memory media of claim 122, wherein said one or more mapping values include a sextant value usable for permuting an order of said intermediate set of coordinate values to generate magnitudes of said final set of coordinate values.

124. The memory media of claim 122, wherein said one or more mapping values include an octant value usable for generating one or more sign bits of said final set of coordinate values.

125. A memory media storing a compressed representation of first surface normal data corresponding to a first three-dimensional surface normal, wherein said first three-dimensional surface normal corresponds to a graphical object, wherein said compressed representation is generated by compressing a first set of three-dimensional surface normal data into a first number of bits by:

selecting a first subset of said first number of bits to indicate which one of a first plurality of symmetrical subsets of all possible three-dimensional normals includes said first three-dimensional surface normal.

126. The memory media of claim 125, wherein said compressed representation is generated utilizing geometric characteristics of said first surface normal.

127. The memory media of claim 125, wherein said compressed representation is generated by encoding information identifying a location of a first point on a surface of a predetermined sphere.

128. The memory media of claim 127, wherein said information identifying said location of said first point includes an index value and one or more mapping values.

129. A system for compressing a first three-dimensional surface normal corresponding to a graphical object, comprising:

a receiving means for receiving first three-dimensional surface normal data which represents said first surface normal;

a compressing means for compressing said first surface normal data utilizing characteristics of said first surface normal, wherein said compressing produces compressed first surface normal data by compressing a first set of three-dimensional surface normal data into a first number of bits by selecting a first subset of said first number of bits to indicate which one of a first plurality of symmetrical subsets of all possible three-dimensional normals includes said first three-dimensional surface normal; and

a storing means for storing said compressed first surface normal data.

130. The system of claim 129, wherein said compressing means is configured to utilize geometric characteristics of said first surface normal in producing said compressed first surface normal data.

131. The system of claim 129, wherein said compressing means is configured to delta-encode said first surface normal data relative to previously specified surface normal data.

132. The system of claim 129, wherein said compressing means is configured to compress said first surface normal data by encoding information identifying a location of a first point on a surface of a predetermined sphere.

133. A system for compressing a first three-dimensional surface normal corresponding to a graphical object, comprising:

a receiving means for receiving first three-dimensional surface normal data which represents said first three-dimensional surface normal;

a compressing means for compressing said first surface normal data by compressing a first set of three-dimensional surface normal data into a first number of bits by selecting a first subset of said first number of bits to indicate which one of a first plurality of symmetrical subsets of all possible three-dimensional normals includes said first three-dimensional surface normal, wherein said compressing produces compressed first surface normal data; and

a transferring means for storing said compressed first surface normal data.

134. The system of claim 133, wherein said compressing means is configured to utilize geometric characteristics of said first surface normal in producing said compressed first surface normal data.

135. The system of claim 133, wherein said compressing means is configured to delta-encode said first surface normal data relative to previously specified surface normal data.

136. The system of claim 133, wherein said compressing means is configured to compress said first surface normal data by encoding information identifying a location of a first point on a surface of a predetermined sphere.

137. A computer-implemented method for compressing a first three-dimensional vector, comprising:

receiving data corresponding to said first three-dimensional vector;

compressing said data corresponding to said first three-dimensional vector by encoding information identifying a location of a first point on a surface of a predetermined sphere, wherein said compressing produces compressed three-dimensional vector data, and wherein said predetermined sphere represents all possible three-dimensional surface normals;

storing said compressed three-dimensional vector data.

138. The method of claim 137, wherein said predetermined sphere is centered on an origin of a first set of coordinate axes which define a first coordinate space, and wherein said data corresponding to said first three-dimensional vector includes a first set of coordinate values.

139. The method of claim 138, wherein said location of said first point is approximated by an intersection of said surface of said predetermined sphere and a vector extended from said origin of said first set of coordinate axes in a direction specified by said first three-dimensional vector.

140. The method of claim 138, wherein said location of said first point on said surface of said predetermined sphere is specified by said fat set of coordinate values.

141. The method of claim 140, wherein said compressing said data corresponding to said first three-dimensional vector includes specifying an index value and one or more mapping values.

142. The method of claim 141, wherein said index value is usable to select an intermediate set of coordinate values from a plurality of predetermined sets of coordinate values, wherein said intermediate set of coordinate values correspond to a second point on said surface of said predetermined sphere.

143. The method of claim 142, wherein each of said plurality of predetermined sets of coordinate values correspond to a point within a predetermined surface region of said predetermined sphere.

144. The method of claim 142, wherein said one or more mapping values are usable to generate magnitudes of a final set of coordinate values from said intermediate get of coordinate values, wherein said final set of coordinate values correspond to said first point.

145. The method of claim 144, wherein said predetermined surface region of said predetermined sphere is a predetermined sextant region of a predetermined octant region.

146. The method of claim 144, wherein said one or more mapping values include an octant value for specifying one or more sign bits of components of said first three-dimensional vector.

147. The method of claim 144, wherein said one or more mapping values include a sextant value which is usable to permute coordinate components of said intermediate set of coordinate values in order to generate said magnitudes of said final set of coordinate values.