MULTI-SENSOR COMPRESSIVE IMAGING

• US 20150030256A1
• Filed: 10/10/2014
• Published: 01/29/2015
• Est. Priority Date: 05/09/2012
• Status: Active Grant

• Current Assignee: Duke University
• Original Assignee: Duke University
• Inventors: Brady, David, Driscoll, Tom, Hunt, John, Marks, Daniel, Mrozack, Alexander, Reynolds, Matthew, Smith, David R.
• Granted Patent: US 9,411,042 B2
• Time in Patent Office: Days
• US Class Current: 382/254
• CPC Class Codes: G01H 17/00 Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves, not provided for in the preceding groups see provisionally also G01H1/00
• CPC Class Codes: G01S 13/887 for detection of concealed objects, e.g. contraband or weapons
• CPC Class Codes: G01S 13/89 for mapping or imaging
• CPC Class Codes: G01S 15/89 for mapping or imaging
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G06T 11/003 Reconstruction from projections, e.g. tomography
• CPC Class Codes: G06T 2207/20021 Dividing image into blocks, subimages or windows
• CPC Class Codes: G06T 2207/30196 Human being; Person
• CPC Class Codes: H01Q 15/0086 said selective devices having materials with a synthesized negative refractive index, e.g. metamaterials or left-handed materials
• CPC Class Codes: H01Q 21/061 Two dimensional planar arrays
• CPC Class Codes: H01Q 3/24 varying the orientation by switching energy from one active radiating element to another, e.g. for beam switching

Abstract

Multi-sensor compressive imaging systems can include an imaging component (such an an RF, microwave, or mmW metamaterial surface antenna) and an auxialiary sensing component (such as an EO/IR sensor). In some approaches, the auxiliary sensing component includes a structured light sensor configured to identify the location or posture of an imaging target within a field of view of the imaging component. In some approaches, a reconstructed RF, microwave, or mmW image may be combined with a visual image of a region of interest to provide a multi-spectral representation of the region of interest.

Claims

1. A method, comprising:

identifying a region of interest within a field of view;

illuminating the region of interest with one or more illumination field patterns;

observing the illuminated region of interest with one or more measurement field patterns; and

reconstructing an image of the region of interest using a compressive imaging algorithm.

2. The method of claim 1, wherein the identifying of the region of interest includes determining spatial information about a subject.

3. The method of claim 2, wherein the determining includes determining by optical or infrared sensing.

4. The method of claim 3, wherein the optical or infrared sensing includes structured light sensing.

5. The method of claim 3, wherein the optical or infrared sensing includes LIDAR sensing.

6. The method of claim 3, wherein the optical or infrared sensing includes photographic or videographic sensing.

7. The method of claim 6, wherein the photographic or videographic sensing includes stereo photographic or videographic sensing.

8. The method of claim 3, wherein the determining including determining by acoustic sensing.

9. The method of claim 3, wherein the determining includes determining by tactile sensing.

10. The method of claim 9, wherein the tactile sensing is subject footstep sensing with a touch-sensitive floor covering.

11. The method of claim 2, wherein the determined spatial information includes subject location information.

12. The method of claim 2, wherein the determined spatial information includes subject orientation information.

13. The method of claim 2, wherein the determined spatial information includes subject posture information.

14. The method of claim 2, wherein the identified region of interest is a volume at least partially enclosing the subject.

15. The method of claim 14, wherein the volume encloses a selected anatomical region of the subject.

16. The method of claim 14, wherein the volume entirely encloses the subject.

17. The method of claim 14, wherein the volume entirely encloses any extent of the subject within the field of view.

18. The method of claim 14, wherein the volume is a polyhedral volume.

19. The method of claim 18, wherein the polyhedral volume is a hexahedral volume.

20. The method of claim 19, wherein the hexahedral volume is a parallelepiped, cuboid, or quadrilateral frustum.

21. The method of claim 2, wherein the determined spatial information includes a depth map characterizing a surface region of the subject.

22. The method of claim 21, wherein the identified region of interest is a volume bounded by the depth map and at least partially enclosing the subject.

23. The method of claim 21, wherein the depth map defines a two-dimensional manifold corresponding to the surface region, and the identified region of interest is a curved slab corresponding to a three-dimensional neighborhood of the two-dimensional manifold.

24. The method of claim 23, wherein the curved slab has a thickness of 15 centimeters or less.

25. The method of claim 23, wherein the curved slab has a thickness of 10 centimeters or less.

26. The method of claim 23, wherein the curved slab has a thickness of 5 centimeters or less.

27. The method of claim 23, wherein the curved slab has a thickness of 1 centimeter or less.

28. The method of claim 1, wherein:

the illuminating of the region of interest includes illuminating the region of interest with the one or more illumination field patterns at one or more RF frequencies; and

the observing of the illuminated region of interest includes observing the region of interest with a one or more measurement field patterns at the one or more RF frequencies.

29. The method of claim 28, w herein the one or more RF frequencies are one or more microwave frequencies.

30. The method of claim 28, wherein the one or more RF frequencies are one or more mmW frequencies.

31. The method of claim 1, wherein the one or more illumination field patterns are radiation patterns of a frequency-dispersive antenna, and the illuminating includes:

illuminating the field of view by operating the frequency-dispersive antenna at each frequency in a set of frequencies.

32. The method of claim 1, wherein the one or more illumination field patterns are radiation patterns of a frequency-dispersive antenna, and the illuminating includes:

selecting a set of frequencies corresponding to a set of illumination patterns that concentrate illumination energy on the region of interest; and

illuminating the region of interest by operating the frequency-dispersive antenna at each frequency in the selected set of frequencies.

33. The method of claim 1, wherein the one or more illumination field patterns are radiation patterns of a reconfigurable antenna, and the illuminating includes:

illuminating the field of view by operating the reconfigurable antenna in each configuration in a set of antenna configurations.

34. The method of claim 1, wherein the one or more illumination field patterns are radiation patterns of a reconfigurable antenna, and the illuminating includes:

selecting a set of antenna configurations corresponding to a set of illumination patterns that concentrate illumination energy on the region of interest;

illuminating the region of interest by operating the reconfigurable antenna in each configuration in the selected set of antenna configurations.

35. The method of claim 1, wherein the one or more illumination field patterns are radiation patterns of a frequency-dispersive, reconfigurable antenna, and the illuminating includes:

illuminating the field of view by operating the frequency-dispersive, reconfigurable antenna in each antenna mode in a set of antenna modes, each mode having a frequency and a configuration.

36. The method of claim 35, wherein the selecting of the set of antenna modes includes selecting a set of frequencies and selecting a set of antenna configurations, and the selected set of antenna modes is a direct product of the selected set of frequencies and the selected set of antenna configurations.

37. The method of claim 1, wherein the one or more illumination field patterns are radiation patterns of a frequency-dispersive, reconfigurable antenna, and the illuminating includes:

selecting a set of antenna modes, each mode having a frequency and a configuration, the selected set of antenna modes corresponding to a set of illumination patterns that concentrate illumination energy on the region of interest;

illuminating the region of interest by operating the frequency-dispersive, reconfigurable antenna in each antenna mode in the selected set of antenna modes.

38. The method of claim 37, wherein the selecting of the set of antenna modes includes selecting a set of frequencies and selecting a set of antenna configurations, and the selected set of antenna modes is a direct product of the selected set of frequencies and the selected set of antenna configurations.

39. The method of claim 1, wherein the one or more illumination field patterns are radiation patterns of a steerable antenna, and the illuminating includes:

steering the antenna to concentrate illumination energy on the region of interest.

40. The method of claim 39, wherein the steering is a mechanical steering of the antenna.

41. The method of claim 39, wherein the steerable antenna includes a mechanically adjustable reflecting or refracting element, and the steering is a mechanical adjusting of the reflecting or refracting element.

42. The method of claim 39, wherein the steerable antenna includes an electronically adjustable reflecting or refracting element, and the steering is an electronic adjusting of the reflecting or refracting element.

43. The method of claim 1, wherein the illuminating includes:

selecting, from a plurality of illumination antennas, one or more illumination antennas having radiation patterns that concentrate illumination energy on the region of interest; and

illuminating the region of interest by operating the one or more selected illumination antennas.

44. The method of any of claims 31 to 43, wherein the observing is a flood observing with a flood measurement field pattern that fills the field of view.

45. The method of claim 1, wherein the one or more measurement field patterns are radiation patterns of a frequency-dispersive antenna, and the observing includes:

observing the field of view by operating the frequency-dispersive antenna at each frequency in a set of frequencies.

46. The method of claim 1, wherein the one or more measurement field patterns are radiation patterns of a frequency-dispersive antenna, and the observing includes:

selecting a set of frequencies corresponding to a set of measurement field patterns that concentrate measurement sensitivity on the region of interest; and

observing the region of interest by operating the frequency-dispersive antenna at each frequency in the selected set of frequencies.

47. The method of claim 1, wherein the one or more measurement field patterns are radiation patterns of a reconfigurable antenna, and the observing includes:

observing the field of view by operating the reconfigurable antenna in each configuration in a set of antenna configurations.

48. The method of claim 1, wherein the one or more measurement field patterns are radiation patterns of a reconfigurable antenna, and the observing includes:

selecting a set of antenna configurations corresponding to a set of measurement field patterns that concentrate measurement sensitivity on the region of interest; and

observing the region of interest by operating the reconfigurable antenna in each configuration in the selected set of antenna configurations.

49. The method of claim 1, wherein the one or more measurement field patterns are radiation patterns of a frequency-dispersive, reconfigurable antenna, and the observing includes:

observing the field of view by operating the frequency-dispersive, reconfigurable antenna in each antenna mode in a set of antenna modes, each mode having a frequency and a configuration.

50. The method of claim 49, wherein the selecting of the set of antenna modes includes selecting a set of frequencies and selecting a set of antenna configurations, and the selected set of antenna modes is a direct product of the selected set of frequencies and the selected set of antenna configurations.

51. The method of claim 1, wherein the one or more measurement field patterns are radiation patterns of a frequency-dispersive, reconfigurable antenna, and the observing includes:

selecting a set of antenna modes, each mode having a frequency and a configuration, the selected set of antenna modes corresponding to a set of measurement field patterns that concentrate measurement sensitivity on the region of interest; and

observing the region of interest by operating the frequency-dispersive, reconfigurable antenna in each antenna mode in the selected set of antenna modes.

52. The method of claim 51, wherein the selecting of the set of antenna modes includes selecting a set of frequencies and selecting a set of antenna configurations, and the selected set of antenna modes is a direct product of the selected set of frequencies and the selected set of antenna configurations.

53. The method of claim 1, wherein the one or more measurement field patterns are radiation patterns of a steerable antenna, and the observing includes:

steering the antenna to concentrate measurement sensitivity on the region of interest.

54. The method of claim 53, wherein the steering is a mechanical steering of the antenna.

55. The method of claim 53, wherein the steerable antenna includes a mechanically adjustable reflecting or refracting element, and the steering is a mechanical adjusting of the reflecting or refracting element.

56. The method of claim 53, wherein the steerable antenna includes an electronically adjustable reflecting or refracting element, and the steering is an electronic adjusting of the reflecting or refracting element.

57. The method of claim 1, wherein the observing includes:

selecting, from a plurality of measurement antennas, one or more measurement antennas having radiation patterns that concentrate measurement sensitivity on the region of interest; and

observing the region of interest by operating the one or more selected measurement antennas.

58. The method of any of claims 45 to 57, wherein the observing is a flood observing with a flood measurement field pattern that fills the field of view.

59. The method of claim 1, where the illumination field patterns and the measurement field patterns define a measurement matrix H, the observing defines a collection of measurements g, and the compressive imaging algorithm solves the minimization problem arg min_f∥

g−

Hf∥

²₂+λ

R(f) for a reconstructed image f, where λ

is a regularization parameter and R(f) is a prior knowledge function.

60. The method of claim 59, where the compressive imaging algorithm is a Two-step Iterated Soft Thresholding (TwIST) algorithm.

61. The method of claim 59, where R(f)=∥

f∥

₁.

62. The method of claim 59, wherein the measurement matrix H is defined only within the region of interest and the reconstructed image f is zero outside the region of interest.

63. The method of claim 59, wherein:

the identifying of the region of interest includes determining a depth map characterizing a surface region of a subject;

the depth map defines a two-dimensional manifold corresponding to the surface region; and

the two-dimensional manifold provides a boundary condition for Green'"'"'s functions of the measurement matrix H.

64. The method of claim 59, wherein:

the identifying of the region of interest includes determining a depth map characterizing a surface region of a subject;

the depth map defines a two-dimensional manifold corresponding to the surface region;

the measurement matrix H is defined only on the two-dimensional manifold; and

the reconstructed image f is a two-dimensional reconstructed image defined on the two-dimensional manifold.

65. The method of claim 21, further comprising:

capturing an optical image of the subject;

combining the depth map, the optical image, and a false-color representation of the reconstructed image to create a three-dimensional image data object.

66. The method of claim 65, further comprising:

displaying the three-dimensional image data object on a monitor.

67. The method of claim 66, further comprising:

zooming or rotating the displayed three-dimensional image data object responsive to a user prompt.

68. The method of claim 67, wherein the monitor is a touch-screen monitor, and the user prompt is a touch-screen gesture.

69. The method of claim 66, further comprising:

identifying a new region of interest responsive to a user prompt.

70. The method of claim 69, further comprising:

illuminating the new region of interest with one or more new illumination field patterns;

observing the illuminated new region of interest with one or more measurement field patterns; and

reconstructing an image of the new region of interest using the compressive imaging algorithm.

71. The method of claim 69, wherein the monitor is a touch-screen monitor, and the user prompt is a touch-screen gesture.

72. A system, comprising:

an illumination antenna having one or more illumination field patterns within a field of view;

a measurement antenna having one or more measurement field patterns within the field of view;

a sensor unit operable to identify a region of interest within the field of view;

a transmitter coupled to an input port of the illumination antenna;

a receiver coupled to an output port of the measurement antenna; and

processing circuitry coupled to the transmitter, the receiver, and the sensor unit and configured to reconstruct an image of the region of interest using a compressive imaging algorithm.

73. The system of claim 72, wherein the sensor unit includes an optical or infrared sensor unit.

74. The system of claim 73, wherein the optical or infrared sensor unit includes a structured light sensor unit.

75. The method of claim 73, wherein the optical or infrared sensor unit includes a LIDAR sensor unit.

76. The system of claim 73, wherein the optical or infrared sensor unit includes an optical or infrared camera.

77. The system of claim 76, wherein the optical or infrared camera is a video camera.

78. The system of claim 73, wherein the optical or infrared camera is a stereo camera.

79. The system of claim 72, wherein the sensor unit includes an acoustic sensor unit.

80. The system of claim 79, wherein the acoustic sensor unit includes an ultrasonic sonar unit.

81. The system of claim 72, wherein the sensor unit includes a tactile sensor unit configured to receive footstep detection signals from a touch-sensitive floor covering.

82. The system of claim 81, further comprising:

the touch-sensitive floor covering coupled to the tactile sensor unit and positioned at least partially on a floor under the field of view.

83. The system of claim 72, wherein the illumination antenna is a frequency-dispersive antenna having a set of illumination field patterns corresponding to a set of frequencies.

84. The system of claim 83, wherein the set of frequencies is a set of RF frequencies.

85. The system of claim 84, wherein the set of RF frequencies is a set of microwave frequencies.

86. The system of claim 84, wherein the set of RF frequencies is a set of mmW frequencies.

87. The system of claim 83, wherein the frequency-dispersive antenna is a metamaterial surface antenna having a plurality of metamaterial elements with a diverse plurality of resonance frequencies.

88. The system of claim 87, wherein the metamaterial elements are CELC resonators.

89. The system of claim 72, wherein

the illumination antenna is a reconfigurable antenna having a set of illumination field patterns corresponding to a set of antenna configurations that are functions of one or more control inputs,

and the system further comprises:

illumination control circuitry configured to provide the one or more control inputs.

90. The system of claim 89, wherein the reconfigurable antenna is a metamaterial surface antenna having a plurality of adjustable metamaterial elements with respective adjustable physical parameters that are functions of the one or more control inputs.

91. The system of claim 90, wherein the adjustable metamaterial elements are adjustable complementary metamaterial elements.

92. The system of claim 90, wherein the adjustable metamaterial elements are adjustable subwavelength patch elements.

93. The system of claim 90, wherein the adjustable physical parameters include respective resonance frequencies and/or Q-factors.

94. The system of claim 90, wherein the one or more control inputs include respective control voltages for the plurality of adjustable metamaterial elements.

95. The system of claim 94, wherein the adjustable material elements include lumped elements, and the control voltages are bias voltages for the lumped elements.

96. The system of claim 94, wherein the adjustable metamaterial elements have inner conducting regions that are electrically isolated from enclosing conducting regions, and the respective control voltages are voltage differences between the inner conducting regions and the enclosing conducting regions.

97. The system of claim 96, wherein the adjustable metamaterial elements include electrically adjustable material disposed in neighborhoods of gaps between the inner conducting regions and the enclosing regions.

98. The system of claim 97, wherein the electrically adjustable material includes a liquid crystal material or a ferroelectric material.

99. The system of claim 96, wherein the adjustable metamaterial elements include diodes between the inner conducting regions and the enclosing regions.

100. The system of claim 99, wherein the diodes are Schottky diodes, p-n diodes, or varactor diodes.

101. The system of claim 94, wherein:

the adjustable metamaterial elements have inner conducting regions that are electrically isolated from enclosing conducting regions;

the adjustable metamaterial elements include transistors with sources connected to the inner conducting regions and drains connected to the enclosing conducting regions;

and the respective control voltages are gate voltages for the transistors.

102. The system of claim 101, wherein the transistors are MOSFET or HEMT transistors.

103. The system of claim 72 wherein:

the illumination antenna is a frequency-dispersive, reconfigurable antenna having a set of illumination field patterns corresponding to a set of antenna modes, each antenna mode defined by a frequency and an antenna configuration, the antenna configurations being functions of one or more control inputs,

and the system further comprises;

illumination control circuitry configured to provide the one or more control inputs.

104. The system of claim 103, wherein the frequency-dispersive, reconfigurable antenna is a metamaterial surface antenna having a plurality of metamaterial elements with a diverse plurality of resonance frequencies, the metamaterial surface antenna including:

a waveguide coupled to the metamaterial elements;

an RF switch having an input port and a set of output ports, and

a respective set of transmission lines connected between the set of output ports and a set of waveguide feeds distributed along the waveguide;

where the RF switch is switchable by the one or more control inputs.

105. The system of claim 72, wherein the illumination antenna is a steerable antenna, and the system further comprises:

steering control circuitry coupled to the steerable antenna and the sensor unit and configured to steer the antenna towards the region of interest.

106. The system of claim 105, wherein the steerable antenna is a mechanically steerable antenna.

107. The system of claim 106, wherein the mechanically steerable antenna is a metamaterial surface antenna attached to a mechanical steering assembly

108. The system of claim 105, wherein the steerable antenna includes a reflecting or refracting structure that is mechanically adjustable to concentrate illumination energy on the region of interest.

109. The system of claim 105, wherein the steerable antenna includes a reflecting or refracting structure that is electronically adjustable to concentrate illumination energy on the region of interest.

110. The system of claim 72, further comprising:

one or more additional illumination antennas, the illumination antenna and the one or more additional illumination antennas constituting a plurality of illumination antennas; and

an RF switch coupling the transmitter to input ports of the plurality of illumination antennas.

111. The system of claim 110, wherein the system further comprises:

illumination control circuitry coupled to the RF switch and the sensor unit and configured to operate the RF switch to select, from the plurality of illumination antennas, an illumination antenna that targets the region of interest.

112. The system of claim 72, wherein the measurement antenna is a frequency-dispersive antenna having a set of measurement field patterns corresponding to a set of frequencies.

113. The system of claim 112, wherein the set of frequencies is a set of RF frequencies.

114. The system of claim 113, wherein the set of RF frequencies is a set of microwave frequencies.

115. The system of claim 113, wherein the set of RF frequencies is a set of mmW frequencies.

116. The system of claim 112, wherein the frequency-dispersive antenna is a metamaterial surface antenna having a plurality of metamaterial elements with a diverse plurality of resonance frequencies.

117. The system of claim 116, wherein the metamaterial elements are CELC resonators.

118. The system of claim 72, wherein

the measurement antenna is a reconfigurable antenna having a set of measurement field patterns corresponding to a set of antenna configurations that are functions of one or more control inputs, and the system further comprises:

measurement control circuitry configured to provide the one or more control inputs.

119. The system of claim 118, wherein the reconfigurable antenna is a metamaterial surface antenna having a plurality of adjustable metamaterial elements with respective adjustable physical parameters that are functions of the one or more control inputs.

120. The system of claim 119, wherein the adjustable metamaterial elements are adjustable complementary metamaterial elements.

121. The system of claim 119, wherein the adjustable metamaterial elements are adjustable subwavelength patch elements.

122. The system of claim 119, wherein the adjustable physical parameters include respective resonance frequencies and/or Q-factors.

123. The system of claim 119, wherein the one or more control inputs include respective control voltages for the plurality of adjustable metamaterial elements.

124. The system of claim 123, wherein the adjustable material elements include lumped elements, and the control voltages are bias voltages for the lumped elements.

125. The system of claim 123, wherein the adjustable metamaterial elements have inner conducting regions that are electrically isolated from enclosing conducting regions, and the respective control voltages are voltage differences between the inner conducting regions and the enclosing conducting regions.

126. The system of claim 125, wherein the adjustable metamaterial elements include electrically adjustable material disposed in neighborhoods of gaps between the inner conducting regions and the enclosing regions.

127. The system of claim 126, wherein the electrically adjustable material includes a liquid crystal material or a ferroelectric material.

128. The system of claim 125, wherein the adjustable metamaterial elements include diodes between the inner conducting regions and the enclosing regions.

129. The system of claim 128, wherein the diodes are Schottky diodes, p-n diodes, or varactor diodes.

130. The system of claim 123, wherein:

the adjustable metamaterial elements have inner conducting regions that are electrically isolated from enclosing conducting regions;

the adjustable metamaterial elements include transistors with sources connected to the inner conducting regions and drains connected to the enclosing conducting regions;

and the respective control voltages are gate voltages for the transistors.

131. The system of claim 130, wherein the transistors are MOSFET or HEMT transistors.

132. The system of claim 72 wherein:

the measurement antenna is a frequency-dispersive, reconfigurable antenna having a set of measurement field patterns corresponding to a set of antenna modes, each antenna mode defined by a frequency and an antenna configuration, the antenna configurations being functions of one or more control inputs,

and the system further comprises;

measurement control circuitry configured to provide the one or more control inputs.

133. The system of claim 132, wherein the frequency-dispersive, reconfigurable antenna is a metamaterial surface antenna having a plurality of metamaterial elements with a diverse plurality of resonance frequencies, the metamaterial surface antenna including:

a waveguide coupled to the metamaterial elements;

an RF switch having an input port and a set of output ports, and

a respective set of transmission lines connected between the set of output ports and a set of waveguide feeds distributed along the waveguide;

where the RF switch is switchable by the one or more control inputs.

134. The system of claim 72, wherein the measurement antenna is a steerable antenna, and the system further comprises:

steering control circuitry coupled to the steerable antenna and the sensor unit and configured to steer the antenna towards the region of interest.

135. The system of claim 134, wherein the steerable antenna is a mechanically steerable antenna.

136. The system of claim 135, wherein the mechanically steerable antenna is a metamaterial surface antenna attached to a mechanical steering assembly

137. The system of claim 134, wherein the steerable antenna includes a reflecting or refracting structure that is mechanically adjustable to concentrate measurement sensitivity on the region of interest.

138. The system of claim 134, wherein the steerable antenna includes a reflecting or refracting structure that is electronically adjustable to concentrate measurement sensitivity on the region of interest.

139. The system of claim 72, further comprising:

one or more additional measurement antennas, the measurement antenna and the one or more additional measurement antennas constituting a plurality of measurement antennas; and

an RF switch coupling the receiver to output ports of the plurality of measurement antennas.

140. The system of claim 139, wherein the system further comprises:

measurement control circuitry coupled to the RF switch and the sensor unit and configured to operate the RF switch to select, from the plurality of measurement antennas, a measurement antenna that targets the region of interest.

141. The system of claim 72, wherein:

the sensor unit is configured to provide a depth map and an optical image of a subject in the field of view; and

the processing circuitry includes a graphics processing unit configured to combine the depth map, the optical image, and a false color representation of the reconstructed image as a three-dimensional graphics image object.

142. The system of claim 141, further comprising:

a monitor coupled to the processing circuitry,

wherein the graphics processing unit is configured to display the three-dimensional graphics image object on the monitor.

143. The system of claim 142, wherein the monitor is a touch-screen monitor.

144. The system of claim 143, wherein the graphics processing unit is configured to zoom or rotate the three-dimensional graphics image object responsive to a gesture on the touch-screen monitor.

145. The system of claim 141, further comprising:

a user interface coupled to the processing circuitry.

146. The system of claim 145, wherein the graphics processing unit is configured to zoom or rotate the three-dimensional graphics image object responsive to an input from the user interface.

147. A system, comprising:

an antenna having a set of radiation patterns within a field of view;

a sensor unit operable to identify a region of interest within the field of view;

a transceiver coupled to the antenna; and

processing circuitry coupled to the transceiver and the sensor unit and configured to reconstruct an image of the region of interest using a compressive imaging algorithm.

148. The system of claim 147, wherein the sensor unit includes an optical or infrared sensor unit.

149. The system of claim 148, wherein the optical or infrared sensor unit includes a structured light sensor unit.

150. The method of claim 148, wherein the optical or infrared sensor unit includes a LIDAR sensor unit.

151. The system of claim 148, wherein the optical or infrared sensor unit includes an optical or infrared camera.

152. The system of claim 151, wherein the optical or infrared camera is a video camera.

153. The system of claim 151, wherein the optical or infrared camera is a stereo camera.

154. The system of claim 147, wherein the sensor unit includes an acoustic sensor unit.

155. The system of claim 154, wherein the acoustic sensor unit includes an ultrasonic sonar unit.

156. The system of claim 147, wherein the sensor unit includes a tactile sensor unit configured to receive footstep detection signals from a touch-sensitive floor covering.

157. The system of claim 156, further comprising:

the touch-sensitive floor covering coupled to the tactile sensor unit and positioned at least partially on a floor under the field of view.

158. The system of claim 147, wherein the antenna is a frequency-dispersive antenna having a set of radiation patterns corresponding to a set of frequencies.

159. The system of claim 158, wherein the set of frequencies is a set of RF frequencies.

160. The system of claim 159, wherein the set of RF frequencies is a set of microwave frequencies.

161. The system of claim 159, wherein the set of RF frequencies is a set of mmW frequencies.

162. The system of claim 158, wherein the frequency-dispersive antenna is a metamaterial surface antenna having a plurality of metamaterial elements with a diverse plurality of resonance frequencies.

163. The system of claim 162, wherein the metamaterial elements are CELC resonators.

164. The system of claim 147, wherein

the antenna is a reconfigurable antenna having a set of radiation patterns corresponding to a set of antenna configurations that are functions of one or more control inputs,

and the system further comprises:

control circuitry configured to provide the one or more control inputs.

165. The system of claim 164, wherein the reconfigurable antenna is a metamaterial surface antenna having a plurality of adjustable metamaterial elements with respective adjustable physical parameters that are functions of the one or more control inputs.

166. The system of claim 165, wherein the adjustable metamaterial elements are adjustable complementary metamaterial elements.

167. The system of claim 165, wherein the adjustable metamaterial elements are adjustable subwavelength patch elements.

168. The system of claim 165, wherein the adjustable physical parameters include respective resonance frequencies and/or Q-factors.

169. The system of claim 165, wherein the one or more control inputs include respective control voltages for the plurality of adjustable metamaterial elements.

170. The system of claim 169, wherein the adjustable material elements include lumped elements, and the control voltages are bias voltages for the lumped elements.

171. The system of claim 169, wherein the adjustable metamaterial elements have inner conducting regions that are electrically isolated from enclosing conducting regions, and the respective control voltages are voltage differences between the inner conducting regions and the enclosing conducting regions.

172. The system of claim 170, wherein the adjustable metamaterial elements include electrically adjustable material disposed in neighborhoods of gaps between the inner conducting regions and the enclosing regions.

173. The system of claim 171, wherein the electrically adjustable material includes a liquid crystal material or a ferroelectric material.

174. The system of claim 170, wherein the adjustable metamaterial elements include diodes between the inner conducting regions and the enclosing regions.

175. The system of claim 173, wherein the diodes are Schottky diodes, p-n diodes, or varactor diodes.

176. The system of claim 169, wherein:

the adjustable metamaterial elements have inner conducting regions that are electrically isolated from enclosing conducting regions;

the adjustable metamaterial elements include transistors with sources connected to the inner conducting regions and drains connected to the enclosing conducting regions;

and the respective control voltages are gate voltages for the transistors.

177. The system of claim 175, wherein the transistors are MOSFET or HEMT transistors.

178. The system of claim 147, wherein:

the antenna is a frequency-dispersive, reconfigurable antenna having a set of radiation patterns corresponding to a set of antenna modes, each antenna mode defined by a frequency and an antenna configuration, the antenna configurations being functions of one or more control inputs,

and the system further comprises;

control circuitry configured to provide the one or more control inputs.

179. The system of claim 177, wherein the frequency-dispersive, reconfigurable antenna is a metamaterial surface antenna having a plurality of metamaterial elements with a diverse plurality of resonance frequencies, the metamaterial surface antenna including:

a waveguide coupled to the metamaterial elements;

an RF switch having an input port and a set of output ports, and

a respective set of transmission lines connected between the set of output ports and a set of waveguide feeds distributed along the waveguide;

where the RF switch is switchable by the one or more control inputs.

180. The system of claim 147, wherein the antenna is a steerable antenna, and the system further comprises:

steering control circuitry coupled to the steerable antenna and the sensor unit and configured to steer the antenna towards the region of interest.

181. The system of claim 179, wherein the steerable antenna is a mechanically steerable antenna.

182. The system of claim 180, wherein the mechanically steerable antenna is a metamaterial surface antenna attached to a mechanical steering assembly

183. The system of claim 179, wherein the steerable antenna includes a reflecting or refracting structure that is mechanically adjustable to target the region of interest.

184. The system of claim 179, wherein the steerable antenna includes a reflecting or refracting structure that is electronically adjustable to target the region of interest.

185. The system of claim 147, further comprising:

one or more additional antennas, the antenna and the one or more additional antennas constituting a plurality of antennas; and

an RF switch coupling the transceiver to the plurality of antennas.

186. The system of claim 184, wherein the system further comprises:

control circuitry coupled to the RF switch and the sensor unit and configured to operate the RF switch to select, from the plurality of antennas, an antenna that targets the region of interest.

187. The system of claim 147, wherein:

the sensor unit is configured to provide a depth map and an optical image of a subject in the field of view; and

the processing circuitry includes a graphics processing unit configured to combine the depth map, the optical image, and a false color representation of the reconstructed image as a three-dimensional graphics image object.

188. The system of claim 186, further comprising:

a monitor coupled to the processing circuitry,

wherein the graphics processing unit is configured to display the three-dimensional graphics image object on the monitor.

189. The system of claim 187, wherein the monitor is a touch-screen monitor.

190. The system of claim 188, wherein the graphics processing unit is configured to zoom or rotate the three-dimensional graphics image object responsive to a gesture on the touch-screen monitor.

191. The system of claim 187, further comprising:

a user interface coupled to the processing circuitry.

192. The system of claim 190, wherein the graphics processing unit is configured to zoom or rotate the three-dimensional graphics image object responsive to an input from the user interface.