WO2001080550A2

WO2001080550A2 - A panoramic camera

Info

Publication number: WO2001080550A2
Application number: PCT/IB2001/000600
Authority: WO
Inventors: Manfred Rudolf Scriba
Original assignee: Csir
Priority date: 2000-04-13
Filing date: 2001-04-09
Publication date: 2001-10-25
Also published as: AU4446501A; WO2001080550A3

Abstract

The invention relates to a panoramic camera. An achromatic lens or reflector arrangement is provided which is configured to enhance the far field resolution of a light sensor. The camera includes rotation means for rotating the sensor and the lens arrangement about an axis of rotation, and a processor for receiving and processing the image signal. The camera may include filter positioning means to which at least one filter is operatively mountable and which is configured selectively to position a filter into an optical path of the lens arrangement. A housing is provided which comprises upper and lower sections, and rotatable mounting means for rotatably mounting the upper section to the lower section which communicate via an optical communication link comprising upper and lower optoelectronic devices. The invention extends to a panoramic camera system and to a method of capturing images in a panoramic camera.

Description

A PANORAMIC CAMERA

THIS INVENTION relates to a panoramic camera. It also relates to a panoramic camera system, to a method of capturing images in a panoramic camera, and to a method of communicating image data in a panoramic camera.

According to the invention, there is provided a panoramic camera which includes light sensing means for sensing light from a field of view and providing an image signal in response thereto; a lens arrangement for focusing the light onto the light sensing means, the lens arrangement being an achromatic lens arrangement or reflector arrangement configured to enhance the far field resolution of the light sensing means; rotation means for rotating the light sensing means and the lens arrangement about an axis of rotation; and processor means for receiving and processing the image signal to provide a converted output signal.

Accordingly, the invention extends to a method of capturing images in a panoramic camera, the method including modifying light rays incident upon sensing means of the panoramic camera by means of an achromatic lens arrangement or reflector arrangement, thereby to enhance the far field resolution of the camera.

Further in accordance with the invention, there is provided a panoramic camera which includes light sensing means for sensing light from a field of view and providing an image signal in response thereto; a lens arrangement for focusing the light onto the light sensing means; rotation means for rotating the light sensing means and the lens arrangement about an axis of rotation; filter positioning means to which at least one filter is operatively mountable and which is configured selectively to position the at least one filter into an optical path of the lens arrangement; and processor means for receiving and processing the image signal to provide a converted output signal.

Accordingly, the invention extends to a method of capturing images in a panoramic camera, the method including selectively positioning at least one filter into an optical path of a lens arrangement of the camera.

Further in accordance with the invention, there is provided a panoramic camera which includes a housing comprising upper and lower sections, and rotatable mounting means for rotatably mounting the upper section to the lower section; light sensing means for sensing light from a field of view and providing an image signal in response thereto, the light sensing means being mounted to the upper section; a lens arrangement for focusing the light onto the light sensing means, the lens arrangement being mounted to the upper section; rotation means for rotating the upper section about an axis of rotation; processor means for receiving and processing the image signal to provide a converted output signal; interface means for interfacing the camera to display means; and an optical communication link comprising upper and lower optoelectronic devices, the upper optoelectronic device being mounted in the upper section and the lower optoelectronic device being mounted in the lower section and being operable to communicate with each other during relative rotation between the upper and lower sections.

The optical communication link may include a slip ring arrangement.

Accordingly, the invention extends to a method of communicating image data in a panoramic camera which has a housing comprising upper and lower sections which operatively rotate relative to each other, the method including communicating at least image data optically between the upper and lower sections.

The camera may include a filter positioning means to which at least one filter is operatively mounted and which is configured selectively to position the at least one filter into an optical path of the lens arrangement. Preferably, filter positioning means includes filter mounting means for mounting a plurality of filters, and filter displacement means arranged selectively to position a filter in the optical path of the lens arrangement.

The invention extends to a method of operating a camera as described, and which includes changing the filters selectively. It extends also to a method which includes the step of positioning a different filter in the optical path after a complete rotation of the light sensing means and the lens arrangement. If desired the method may include the step of changing the filters as a function of time, or in response to changing environmental conditions, or because of other factors.

The lens arrangement or reflector arrangement may be an achromatic lens arrangement, e.g. a achromatic prism, aspherical reflector, or the like, configured to enhance the far field resolution of the light sensing means. Thus, the sensitivity of the camera to objects in the near and far fields of the lens arrangement may be balanced, by adjusting the positioning of the achromatic prism arrangement or the reflector arrangement.

The light sensing means may be a multi-spectral light sensor which includes three spaced linear sensor elements for sensing or detecting RED, GREEN and BLUE light. The sensor elements may be linear elements which are disposed transversely to and spaced laterally in the direction of rotation, and each sensor element may comprise a plurality of pixels dedicated to receiving light of a specific frequency/wave length. Due to the spacing between adjacent linear sensor elements and the passage of the light through the optical arrangement, light of a different frequency, e.g. BLUE, GREEN, and RED light, sensed by a particular sensor element is sourced from a different and spaced object line in the field of view, usually a laterally spaced object line.

Accordingly, as the camera is rotated there may be a lag or delay or angular error in image data detected by the light sensing means.

Thus, the processor means may include compensation means for compensating for the lag or delay or angular error due to the lateral spacing of the linear sensor elements, each of which is dedicated to sensing light of a different frequency.

The method may include the steps of receiving serial pixel data from each one of three sensor elements of the sensing means; and compensating the serial pixel data from two of the three sensor elements to produce pixel data including light sourced from a common object line.

The compensation means may include a shift register or the like operating on a first in first out (FIFO) basis. Accordingly, each sensor output may have its output connected to an analog to digital converter to provide a flow of parallel digital output of sensor data. All subsequent manipulation or processing of the pixel data sourced from the light sensing means may thus be carried out digitally. Preferably, electrical signals from the light sensing means are immediately converted into a 1 2 bit digital format. Thus, the method may include feeding the output from each sensor element into an analog to digital converter; and delaying pixel data from two of the three sensor elements to provide a flow of parallel digital pixel data.

In certain embodiments of the invention, an analog output of the light sensing means may be multiplexed in analog and the multiplexed output may then be fed into an analog to digital converter (A/D converter). In this embodiment a single A/D converter may be used instead of three separate A/D converters each connected to a sensor element.

The camera may thus include a multiplexer for converting three streams of parallel data from the sensor elements into a parallel configuration in which corresponding pixel information from different sensor elements is sequentially passed through the same data bus.

A camera having its light sensing means in the form of three monochrome linear sensors may include a beam splitter assembly for splitting the light to be incident on the three monochrome linear sensors.

Accordingly, the invention extends to a panoramic camera which includes a beam splitter assembly.

The processor means may be arranged digitally to provide black level clamping, binning, or the like. Preferably, the processor means includes encryption means for encrypting data captured by the camera and transmitted to a central display or monitoring facility. The camera may include identification means for uniquely identifying the camera. For example, the identification means may be a unique camera number, date and/or time data, or the like. Identification data may be included in the digital image data.

The camera may include security means for securing the camera against unauthorised use. The security means may include disabling means for selectively disabling operation of the camera. In certain circumstances, the security means my be a hardware component, e.g. a PIC microcontroller or the like, which is responsive to a control signal from a remote device e.g. a control signal from a PC at a monitoring facility.

The processor means may include simulation means for simulation of rotation of the light sensing means when it is in fact stationary. The simulation means may estimate a scanning frequency of the camera so that a single line of object data may be captured. The camera may be instructed by a monitoring facility to enter into a stationary mode to facilitate adjustment of camera optics e.g. focusing of a lens or the like. Accordingly, the method includes the steps of selectively holding the light sensing means stationary and providing simulation means operable to simulate the pulses, to permit data to be clocked from the light sensing means.

The processor means may include simulation means that transmits a test pattern to the display means at the monitoring facility. Typically, the test pattern is used for testing the communication link, the processor means, and receiver means of the system. Further tests may optionally be included.

In certain embodiments, communication between the upper section, within which the light sensing means is housed, and circuitry in the lower section is by way of a slip-ring arrangement.

The rotation means may include a rotation motor having a drive shaft and drive chain or belt. For the purposes of this specification, the term "rotation" is intended to include part rotation or angular displacement, sweeping, or the like.

The camera may include position detection means for detecting a rotational or angular position of the light sensing means or upper section. For example, the camera may include a shaft encoder or the like which generates pulses as the drive shaft of the motor is rotated. The pulses are dependent on the position of the shaft and an angular velocity of the shaft. The pulses are used to clock pixel data from the light sensing means. In the event of the light sensing means being stationary, the simulation means may simulate the pulses to permit data to be clocked from the light sensing means.

The method may thus include generating pulses as the drive shaft of the motor is rotated, the pulses being dependent on the position of the shaft and the angular velocity of the shaft; and using the pulses to clock pixel data from the light sensing means. The invention extends also to a panoramic camera system which includes at least one panoramic camera as described above; and a monitoring facility which includes a personal computer with display, operatively connected to the camera.

The operative connection between the monitoring facility and the camera is via transmitters and cooperating receivers. Thus, the camera may include a receiver, preferably a transceiver, mounted in the lower section for communicating with the remote monitoring facility. The receiver may be configured to communicate via copper wire, fibre optics, microwaves, radio waves, satellite, a cellular communication network, a laser link, a conventional telephone link, or the like. Communication may be in a serial or parallel format.

Instructions to the camera to enter a stationary mode may be sent from the monitoring facility, to facilitate adjustment of camera optics, e.g. focusing, or the like.

The simulation means may be capable of transmitting a test pattern and the monitoring facility may have receiving means for receiving the test pattern.

The test pattern may be used for testing the adequacy of the processor means, the communication link, and its components, such as transmitters and receivers. The camera may advantageously be used in a system for fire detection, for security monitoring purposes, for harbour and airport control, coastline monitoring, or the like. In certain embodiments, the camera is linked to the Internet. For example, control of operation of the camera may take place via the Internet and images captured by the camera may be communicated via the Internet.

The invention extends to a panoramic camera system including at least one panoramic camera as hereinbefore described.

The invention is now described, by way of example, with reference to the accompanying diagrammatic drawings.

In the drawings. Figure 1 shows a schematic representation of a panoramic camera in accordance with the invention;

Figure 2 shows a schematic block diagram of a panoramic camera system, also in accordance with the invention, including the panoramic camera of Figure 1 ;

Figure 3 shows a schematic communication block diagram of the system of Figure 2;

Figure 4 shows a schematic block diagram of circuitry associated with a multi-spectral line sensor of the panoramic camera;

Figure 5 shows a schematic block diagram of a motor and encoder arrangement of the camera;

Figure 6 shows a schematic block diagram of conversion of parallel data to serial data which is communicated via a communication link; Figure 7 shows a schematic block diagram of the manipulation of image data received from the camera for display or processing;

Figure 8 shows a schematic representation of a filter arrangement of the camera; Figures 9 to 1 1 show schematic representations of various filter mounting means of the filter arrangement;

Figure 1 2 shows a schematic representation of an embodiment of the invention which includes an aspherical reflector;

Figure 1 3 shows a schematic representation of a further embodiment of the invention which includes a deforming prism assembly;

Figure 14 shows a schematic representation of a beam splitter assembly used in certain embodiments of the camera;

Figure 1 5 shows a longitudinal sectional view of an optical slip ring arrangement; Figure 1 6 shows a three-dimensional view of a housing of the panoramic camera; and

Figure 1 7 shows an exploded view of the housing of Figure 1 6.

Referring to the drawings, reference numeral 10 (see Figure 2) generally indicates a panoramic camera system in accordance with the invention. The system 10 includes a panoramic camera 1 2 (see Figures

1 and 2) connected to a central monitoring station 1 4 which may be connected to a plurality of differently positioned panoramic cameras 1 2. The central monitoring station 14 includes a personal computer 1 6 with appropriate software 1 7 for displaying and manipulating image date captured by the camera 1 2. The camera 1 2 includes a multi-spectral line sensor 1 8, which senses an object image 20 (see Figure 1 ) via a lens arrangement 22. In order for the sensor 1 8 to capture a two-dimensional image, it is rotated by rotation means 24, as described in more detail below. A filter arrangement 26 (see Figure 2) including a filter motor 28, filter mounting means 30, and a filter encoder 32 is provided.

The camera 1 2 further includes processor means in the form of control electronics 34 which controls the operation of the camera 1 2 as described in more detail below. Image data from the control electronics 34 is communicated via slip rings 36 to a data transceiver 38 mounted in the camera 1 2. Data from the data transceiver 38 is communicated via a communication link 40 to the central monitoring station 1 4. The communication link 40 may be a fibre optic link, a copper cable link, a microwave link, a laser link, a radio link, or the like. The specific type of link is chosen dependent on the specific application and distance between the camera 1 2 and the central monitoring station 1 4.

The lens arrangement 22 includes a conventional lens and lens mounting arrangement, e.g. a conventional Nikon™ lens mounting arrangement, for mounting the lens arrangement relative to the multi- spectral line sensor 1 8. The sensor 1 8 is a three element line sensor wherein each element corresponds to a particular frequency/wavelength of light. Accordingly, a first linear element of the sensor detects RED light, a second element detects GREEN light, and a third element detects BLUE light. The sensor 1 8 may be a conventional sensor currently available in the market-place which provides the three lines or elements in a parallel laterally spaced fashion with a spacing typically of between four and eight lines between each of the elements. The lens arrangement 22 and the sensor 1 8 are mounted on a rotation platform 42 (see Figures 2 and 8) in such a fashion so that a field of view (FOV) of the sensor 18 extends outwardly about an axis of rotation 1 9 of the sensor 1 8.

The platform 42 is rotated or panned by means of a rotation motor 44 (see Figure 2) which has an associated rotation encoder 46 for determining a position of a shaft of the rotation motor 44. The platform 42 is driven by the rotation motor 44 via a drive belt (not shown) and the rotation encoder 46 generates counting pulses which are directly related to the angular or rotational position of the platform 42, and the frequency of the pulses is directly related to the angular velocity of the rotation platform 42. These pulse signals are used as timing signals for clocking image data from the line sensor 1 8 as well as for speed control for the rotation motor 44. As shown in Figure 5, the control electronics 34 controls operation of the rotation motor 44 and is responsive to pulse data received from the rotation encoder (also referred to as a shaft encoder) 46.

Further, focus and iris motors 48, 50 respectively (see Figures 2 and 5) are provided and are controlled by the control electronics

34. The control electronics 34 also controls the filter motor 28 and is responsive to signals from the filter encoder 32. The focus motor 48 and the iris motor 50 selectively adjust the focus and iris setting of the lens arrangement 22 in response to control signals received from the personal computer 1 6. Further, the rotation motor 44 generates a rotation pulse (see block 52 in Figure 5) which is generated each time the platform 42 has completed a single rotation.

As described in more detail below, timing signals generated by the control electronics 34 (see Figure 5) in response to position data from the rotation encoder 46 are used to clock data from the sensor 18

(see Figure 4) which is then immediately converted into a 1 2 bit digital format by the analog to digital converters 56 (see Figure 4). In the embodiment depicted in the drawings, a multi spectral line sensor 1 8 is used. However, in other embodiments of the invention, a conventional monochrome sensor may be used alone or in combination with the filter arrangement 26. Image data sensed by the sensor 1 8 from each linear element is adjusted as shown at blocks 54 whereafter it is fed into analog to digital converters 56 (see Figures 2 and 4) and, thereafter, into a multiplexer 58 whereafter it is manipulated by the control electronics 34. The digital data from the three linear elements of the sensor 1 8 is multiplexed so that one sample at a time, i.e. data from corresponding pixels in each linear element of the sensor 1 8, is sent in a digital format from the multiplexer 58 for processing by the control electronics 34.

The control electronics 34 includes appropriate software to perform conventional black level clamping techniques, dynamic range stretching, and gain control. Further, due to the spacing between adjacent line sensor elements, and the passage of light through the lens arrangement 22, light of a different frequency, e.g. BLUE, GREEN and RED light, sensed by the particular sensor element of the sensor 1 8 is sourced from a different and spaced object line in the field of view of the camera 1 2. Accordingly, as the camera 1 2 is rotated there may be a lag or delay or angular error in image data at the instant of detection by each sensor element of the sensor 18. In order to compensate for the resultant delay between each sensor element, compensation means defined by the control electronics 34 is provided. The compensation means is in the form of a shift register operating on a FIFO (First In First

Out) principle. In particular, when the camera rotates clockwise, the colour pixels that are received by the control electronics 34 for digital signal processing are typically in the order of line 1 RED, line 6 GREEN, and line 1 1 BLUE, lines 2, 3, 4, 5, 7, 8, 9 and 1 0 being spaces between the sensor elements. It is to be appreciated that the spacing will differ dependent upon the particular sensor used.

The lag or delay or angular error is compensated for by the control electronics 34 in the following repetitive process:

Step 1 Receive RED pixel, line 1; S Stteepp 22 W Wrriittee RED pixel, line 1 to memory location;

Step 3 Read RED pixel, line 1 1 from memory location to camera output;

Step 4 Receive GREEN pixel, line 6;

Step 5 Write GREEN pixel, line 6 to memory location; S Stteepp 66 R Reeaadd GREEN pixel, line 1 1 from memory location to camera output; Step 7 Write BLUE pixel, line 1 1 to camera output directly.

The above sequence is repeated continuously in a shift register type fashion in which memory locations are shifted in a loop thereby to delay pixel data so that the control electronics 34 receives in real time the corrected pixel data from each different linear element of the line sensor 1 8. The above routine delays the RED pixels by eleven full lines and the GREEN pixels by six lines in a digital fashion so that the pixel data received by the control electronics 34 relates to the same object line, e.g. line 1 1 in this example. It is to be appreciated that the sequence set out above will change if the camera is rotated counterclockwise or if the sensor is orientated differently.

The camera 1 2 includes security means and unique identification means for preventing unauthorised use of the camera 1 2 as well as uniquely identifying the camera 1 2 to the central monitoring station 14. In particular, the camera 1 2 includes a unique number for the particular hardware which is programmed into the camera 1 2 during manufacture. The unique number is stored in a protected fashion inside memory of the control electronics 34. In a preferred embodiment, the camera 1 2 includes a hardware component e.g. a PIC microcontroller or the like, which is arranged to provide the unique identification number. The personal computer 1 6 at the central monitoring station 14 may intermittently poll the microcontroller to verify the unique identification number. The camera 1 2 is then arranged so that if it is not correctly polled it will not function. Preferably, communication between the camera 1 2 and any other devices, for example the personal computer 1 6, is encrypted. Accordingly, the control electronics 34 may include encryption means.

Referring in particular to Figures 2 and 3 of the drawings, data from the control electronics 34 is communicated via the slip rings 36 to the data transceiver 38 in data packets. A data packet is typically a line of image information, preceded by the camera number, the line number, and a 32 bit information package. The image data is typically sent in an RS485 format through the slip rings 36. In particular, image data from each line element of the sensor 1 8 is communicated after it has been processed by the control electronics 34 in a line-by-line fashion.

The data packet or package includes a line number calculated from the rotation encoder 46 and is typically 1 6 bits long, followed by the camera number which is given to the camera at manufacture and which is typically also 1 6 bits long. Thereafter, a 32 bit data word including camera settings and other selected information followed by pixel data, sequentially in a RED GREEN BLUE sequence is provided. The slip rings 36 are typically gold plated copper contact slip rings and an RS485 communication protocol is used for improving noise immunity. A power supply 58 provides power to the various components of the camera 1 2 and is also connected to the slip rings 36, which is typically a 24 contact slip ring arrangement. The power supply 58 provides a 24 V DC supply from a 1 10 V AC or 220 V AC mains source. In other embodiments of the invention, the camera 1 2 uses a DC input of 1 2 V or 24 V sourced from a car battery which is optionally connected to wind and/or solar power cells.

The data transceiver 38 converts the parallel data that is received through the slip rings 36 into serial data which is used to drive the communication link 40 (see Figure 6). As indicated above, the communication link 40 may be a microwave, copper, laser, radio or telephone link, or the like communication link depending on the particular application. In one embodiment of the camera, the data transceiver 38 (and parallel to serial converter and serial to parallel converter) is located together with the control electronics 34 on the rotating platform 42. In other embodiments, the data transceiver 38 is not included in the camera 1 2. In this case, image data is transmitted through the slip rings 36 in a parallel fashion, directly to the input/output control 62 (see Figure 3).

The personal computer 1 6 includes a corresponding data transceiver 60 for bi-directional communication with the data transceiver 38. The data transceiver 60 is substantially similar to the data transceiver 38 and an input/output card which operates on the computer bus is provided. The transceiver 60 may, however, also operate on the USB, parallel port or any other PC input/output port that is fast enough to handle the image data received from the camera 1 2.

The input/output card of the personal computer 1 6 captures data from the data transceiver 60 and writes it directly to memory (see

Figure 7). The input/output card also sources commands or instructions from the personal computer 1 6 and communicates them via the communication link 40 to the camera 1 2, e.g. commands to control the focus motor 48, iris motor 50, filter motor 28, rotation motor 44, and so on.

Referring in particular to Figure 7 of the drawings, the personal computer 1 6 includes input/output circuitry 62 which is connected to a computer bus 64. Data from the input/output circuitry 62 is fed via the computer bus 64 sequentially into first and second image buffers 66, 68 whereafter it is stored in memory 70. The dual buffer arrangement allows data to be written to one of the image buffers whilst the other image buffer transfers its data to the memory 70 for processing or display. Typically, in the embodiment depicted in the drawings, transfer into the memory 70 takes place at about 1 0 megabytes per second. In particular, during a first cycle, the input/output circuitry 62 will write to the second image buffer 68 and the control software in the personal computer 1 6 will transfer the data in the first image buffer 66 to the memory 70. During the second cycle, the input/output circuit will write to the first image buffer 66 and the control software in the personal computer 1 6 will transfer data from the second image buffer 68 into the memory 70. This cycle repeats itself for the duration of operation of the camera 1 2. It is to be appreciated that there may be any number of image buffers.

It is further to be appreciated that the image may be captured in various other ways, for example, it may be captured using conventional image capture hardware, using the USB or other input/output means of the computer, or the like.

In certain embodiments of the invention, the system 10 includes compression technology for compressing the digital image captured by the camera 1 2. The compression technology allows a reduced bandwidth to be used for communicating via the communication link 40. The compression technology forms part of the digital signal processing circuitry which is implemented by the control electronics 34 and may be conventional. In one specific example, a DELTA compression technique is applied so that only the difference between the first and second pixel transmitted is communicated. In a different embodiment applying a different compression technique, the panoramic image captured by the camera 1 2 is divided into smaller blocks and a JPEG compression technique is carried out on each block prior to transmission thereof to the central monitoring station 1 4.

Referring in particular to Figures 8 to 1 1 of the drawings, various embodiments of the filter mounting means 30 are shown. The filter mounting means 30.1 has three apertures or bores 72 over which three different filters (not shown) are mounted. In use, the filter motor 28 is arranged to displace the filter mounting means 30.1 lineally a fixed distance so that one of the filters is positioned in the field of view 74. Displacement of the filter mounting means 30.1 by the filter motor 28 may be predefined and controlled by the control electronics 34 or, the displacement of the filter mounting means 30.1 may be upon receipt of a command from the central monitoring station 14 via the communication link 40. Alternative embodiments of the filter mounting means are shown in Figures 9 to 1 1 . In filter mounting means 30.2 of Figure 9, apertures or bores 72 for mounting different filters are defined in a disc 76 which is rotated in use by the filter motor 28. In Figure 10 of the drawings, the filter mounting means 30.3 is in the form of a plate 78 in which five apertures or bores 72 are defined. The plate 78 is displaced lineally by the filter motor 28. In Figure 1 1 , the filter mounting means 30.4 is in the form of an arcuate bar or plate 78 which has apertures or bores 72 provided therein and is arranged to be rotated thereby to place a different filter in front of the lens arrangement 22.

For' example, when the camera 1 2 includes the filter mounting means 30.1 shown in Figure 8 of the drawings, three filters are mounted over the bores or apertures 72. As is the case with all the various embodiments of the filter mounting means 30, its position is sensed by the filter encoder 32 (see Figure 2) so that a specific filter may be provided in front of the lens arrangement 22. Typically, the filters include an 850 nm long pass filter for sharpening the horizon and reducing the atmospheric back scattered light effect on the camera 1 2; a narrow bandpass filter at 560 nm to assist in identifying vegetation and is typically useful in smoke detection; and a third filter in the form of a polarizing filter for the removal of sunlight and glare. In certain embodiments, a transparent glass filter for use at night is provided. It is however to be appreciated that any number of different filters may be mounted on the filter mounting means 30 to enhance or assist in image detection. For example, the filter mounting means 30 may create pseudo colour images by using three narrow bandpass filters that are all in the near infrared region e.g. 875 nm, 925 nm, and 975 nm. Preferably an auto focus lens with a Nikon™ mount is used in this application and the focal length is typically 27 mm with iris and focus settings of the lens being adjusted by the iris motor 50 and the focus motor 48. As mentioned above, the personal computer 1 6 may be used to adjust the settings via the iris motor 50 and the focus motor 48. In addition, the rotation velocity and various other operating parameters of the camera 1 2 may be adjusted remotely.

In certain embodiments, three filters, which are not in the

RED, BLUE, and GREEN wavelength, may be used to create a false or pseudo colour image which is formed by combining outputs from the sensor elements. The false colour image can be used to enhance certain aspects of the image in a specific light colour. The control electronics 34 processes data from the filter encoder 32, as mentioned above to determine the position of the filter mounting means 30, i.e. which particular filter is in the field of view 74. The rotation encoder 46 on the rotation motor 44 allows clocking of image data from the sensor 1 8 and generates synchronized timing signals for the linear sensors and all other synchronized electronics. The rotation encoder 46 also generates typically about 100000 pulses for each revolution of the panoramic camera 1 2 thereby to enhance the resolution and accuracy of the camera 1 2. A further encoder generates the rotation pulse (see block 52 in Figure 5) which is provided each time a full revolution is completed. This pulse is an absolute fixed reference and is repeatedly generated once the platform 42 reaches this predefined position.

The control electronics 34 is operable to generate the appropriate timing signals even if the rotation motor 44 is stationary and, hence, no timing signals are received from the rotation encoder 46. Thus, the camera 1 2 may have its sensor 1 8 stationary to assist in adjustment of the camera 1 2 e.g. focusing or the like, and nevertheless furnish image data to the central monitoring station 14. Thus, the processor means of the control electronics 34 may simulate the relevant timing signals. This facility of the camera 1 2 may be selectively switched on and off by the control electronics 34.

Similarly, a test pattern generator resides in the control electronics 34. This generator may be activated remotely by the computer 1 6, via the communication link 40. The test pattern generator sends out image data as if it is image data sensed by the sensor 18 i.e. the test pattern is in the same format as the image. The test pattern may be in various different forms and, in a typical embodiment, is (i² + j²) mod 256, where i = the pixel number and j = the line number. The test pattern may be used to test various aspects and components of the system 1 0.

Referring in particular to Figures 1 2 and 1 3 of the drawings, reference numeral 80 generally indicates an achromatic lens arrangement which defines compensation means for enhancing the field of view of the sensor 1 8 for distant objects. The achromatic lens arrangement 80 includes an aspherical reflector 82 positioned relative to the lens arrangement 22 so that light rays 84, sourced from a distant image 86, typically at about 10 km, are amplified relative to light rays 88 sourced from a closer image 90 which is about 500 m from the camera 1 2. Thus, the camera 1 2 compensates the image sensed by the detector 1 8 so that images at greater distances are increased in size thereby to enhance the effectiveness of the camera 1 2.

Referring in particular to Figure 1 3 of the drawings, reference numeral 92 generally indicates a further embodiment of an achromatic lens arrangement and, accordingly, like reference numerals have been used to indicate the same or similar features unless otherwise indicated. In the achromatic lens arrangement 92 a deforming prism assembly 94 is used instead of the aspherical reflector 82 and compensation for distant images is achieved in a similar fashion.

The achromatic lens arrangements 80, 92, as mentioned above, enhance the detection and monitoring capabilities of the system 10. Further, information on a distant image which would otherwise not be sensed by the sensor 1 8 is enhanced and thereby detection thereof is achieved. In particular, in a system in which the achromatic lens arrangement 80, 92 is not used and a normal lens forms an image on a sensor, the field of view of the lens expands from the sensor through the lens to the object viewed. Thus, if this image is formed on an array or line of light sensitive elements the size of the object will decrease on the image as the object is moved away from the lens in the field of view of that lens. However, in the embodiment depicted in the drawings, this effect is compensated for or countered by the addition of the achromatic lens arrangement 80, 92. The achromatic lens arrangement 80, 92 has the effect of increasing the resolution of the far field of view and decreasing the resolution of the near field of view as shown in Figures 1 2 and 1 3. It is believed that the inclusion of the achromatic lens arrangement 80, 92 enhances the ability of the camera 1 2 in the detection of fires in forestry as it has improved fire and/or smoke detection characteristics. Typically, a choice of SKI 6 or SF1 6 glass is used for the prisms 94 as a result of its relative insensitivity to thermal expansion. In the achromatic lens arrangement 92 which includes the deforming prism assembly 94, the sensor 1 8 and the lens arrangement 22 are mounted so that they can be adjusted in order to maintain the line of sight.

In certain embodiments of the invention, an infrared camera that is sensitive in the 3 to 5μm wavelength or in the 1 2 to 1 4 m wavelength is mounted on the platform 42 together with the visual spectrum sensor 1 8. The images of the two systems are then transmitted to the central monitoring station 14 where processing or the like is implemented. In certain embodiments, image fusion where the images are combined or detection algorithms used for the detection of smoke in fire detection applications may be implemented. In other applications, the system 1 0 may be used to detect humans or animals at night or day.

On instruction from the personal computer 1 6, the camera 1 2 may transmit a test image to the personal computer 1 6. The test image may be used to adjust the filters, the focusing, the iris setting, and/or the like.

Referring in particular to Figure 14 of the drawings, the panoramic camera 1 2 may include beam splitter optics 96. The beam splitter assembly or optics may be substantially similar to those used in broadcast cameras and satellite pushbroom cameras. In the beam splitter arrangement optionally used in the camera 1 , light from a lens image 98 enters the beam splitter optics 96 and splits up the incident light beam so that different frequencies are incident upon different sensors 100, 102, 1 04. Each sensor 100, 102, 104 is specifically arranged to be sensitive to a different frequency of light e.g. a RED light sensor, a GREEN light sensor, a BLUE light sensor, or the like. It is believed that it is an advantage of the beam splitter arrangement in that the shift register or compensation arrangement described above is not required. Pseudo colour images may be formed using different filters instead of the RED, GREEN, and BLUE filters used for conventional colour images. These filters may form part of a beam splitter assembly and may be deposited in a conventional fashion thereon. Referring in particular to Figure 1 5 of the drawings, reference numeral 1 10 generally indicates an optical slip ring arrangement which optionally replaces the slip rings 36 shown in Figure 2 of the drawings. The optical slip ring arrangement 1 10 includes an upper optical transceiver device 1 1 2 which communicates via an optical link with a lower optical transceiver device 1 1 4. The upper transceiver device 1 1 2 is mounted on a rotating platform 42 which is mounted by means of bearings (not shown) to a lower or stationary platform 1 1 8. In use, the platform 42 is rotated relative to the stationary platform 1 1 8 in a conventional fashion. The lower transceiver device 1 1 4 may communicate in a substantially similar fashion as described above to the central monitoring station 14. It is believed that by means of the optical slip ring arrangement 1 10 enhanced communication between the control electronics 34 of the camera 1 2 and the data transceiver 38 may be achieved in that there are no direct electrical contacts to communicate image data. Power is transferred from the stationary platform 1 1 8 through a ring transformer 1 1 6 to the rotating platform 42.

Referring in particular to Figures 1 6 and 1 7 of the drawings, reference numeral 1 20 generally indicates a waterproof housing for housing the various components of the panoramic camera 1 2. The housing 120 comprises an upper section 122 and a lower section 1 24 which are rotatably mounted to each other by rotatable mounting means. The upper section 1 22 includes a vertical slit or slot 1 26 which provides a window through which the sensor 1 8 sources its image. A mounting arrangement 1 28 is provided for mounting the housing 1 20 to a support post. In more sophisticated embodiments, the housing 1 20 includes window cleaning means (not shown), e.g. a motorised wiper, or the like. The upper section 1 22 includes a rotation platform 42 which is mounted to a base 1 30. The base is received within a base enclosure 1 32. "O" rings 1 34 are provided to enhance sealing between the upper section 1 22 and the rotation platform 42. Similarly, the base enclosure 1 32 seals with "O" rings 1 34 to the base 1 30. As can be clearly seen in Figure 1 7 of the drawings, the rotation platform 42 includes mounting brackets 1 36 for mounting the various components of the camera 1 2 to the platform 42, for example, the rotation motor 44 and the lens arrangement 22.

The Inventors believe that the invention, as illustrated, provides an enhanced panoramic camera 1 2 for use in a panoramic camera system 1 0.

Claims

CLAIMS:

1 . A panoramic camera which includes light sensing means for sensing light from a field of view and providing an image signal in response thereto; a lens arrangement for focusing the light onto the light sensing means, the lens arrangement being an achromatic lens arrangement or reflector arrangement configured to enhance the far field resolution of the light sensing means; rotation means for rotating the light sensing means and the lens arrangement about an axis of rotation; and processor means for receiving and processing the image signal to provide a converted output signal.

2. A panoramic camera which includes light sensing means for sensing light from a field of view and providing an image signal in response thereto; a lens arrangement for focusing the light onto the light sensing means; rotation means for rotating the light sensing means and the lens arrangement about an axis of rotation; filter positioning means to which at least one filter is operatively mountable and which is configured selectively to position the at least one filter into an optical path of the lens arrangement; and processor means for receiving and processing the image signal to provide a converted output signal.

3. A panoramic camera which includes a housing comprising upper and lower sections, and rotatable mounting means for rotatably mounting the upper section to the lower section; light sensing means for sensing light from a field of view and providing an image signal in response thereto, the light sensing means being mounted to the upper section; a lens arrangement for focusing the light onto the light sensing means, the lens arrangement being mounted to the upper section; rotation means for rotating the upper section about an axis of rotation; processor means for receiving and processing the image signal to provide a converted output signal; interface means for interfacing the camera to display means; and an optical communication link comprising upper and lower optoelectronic devices, the upper optoelectronic device being mounted in the upper section and the lower optoelectronic device being mounted in the lower section and being operable to communicate with each other during relative rotation between the upper and lower sections.

4. A camera as claimed in Claim 3, in which the optical communication link includes a slip ring arrangement.

5. A camera as claimed in any one of the preceding claims 2 to 4, in which the lens arrangement includes an achromatic lens arrangement or reflector arrangement configured to enhance the far field resolution of the light sensing means.

6. A camera as claimed in Claim 1 or Claim 5, in which the achromatic lens arrangement includes an achromatic prism.

7. A camera as claimed in Claim 1 or Claim 5, in which the reflector arrangement includes an aspherical reflector.

8. A camera as claimed in Claim 1 or Claim 3 or Claim 4, which includes a filter positioning means to which at least one filter is operatively mountable, and which is configured selectively to position at least one filter into an optical path of the lens arrangement.

9. A camera as claimed in Claim 2 or Claim 8, in which the filter positioning means includes filter mounting means for mounting a plurality of filters; and filter displacement means arranged selectively to position a filter in the optical path of the lens.

10. A camera as claimed in any one of the preceding claims, in which the light sensing means is a multi-spectral light sensor which includes three spaced linear sensor elements for sensing RED, GREEN and BLUE light.

1 1 . A camera as claimed in Claim 1 0, in which the sensor elements are linear elements which are disposed transversely to and spaced laterally in the direction of rotation, and in which each sensor element comprises a plurality of pixels dedicated to receiving light of a specific frequency/wave length.

1 2. A camera as claimed in Claim 1 1 , in which the processor means includes compensation means for compensating for the lag or delay or angular error due to the lateral spacing of the linear sensor elements.

13. A camera as claimed in Claim 1 2, in which the compensation means includes a shift register operating on a first in first out (FIFO) basis.

14. A camera as claimed in Claim 1 3, in which each sensor has its output connected to an analog to digital converter.

1 5. A camera as claimed in any one of the preceding claims 10 to 14 inclusive, which includes a multiplexer for converting the three streams of parallel data from the sensor elements into a parallel configuration.

1 6. A camera as claimed in any one of the preceding claims 1 to 9 inclusive, in which the light sensing means is in the form of three monochrome linear sensors, and in which there is provided a beam splitter assembly for splitting the light to be incident on the three monochrome linear sensors.

1 7. A camera as claimed in any one of the preceding claims 1 to 1 6 inclusive, in which the processor means digitally provides black level clamping or binning.

1 8. A camera as claimed in any one of the preceding claims 1 to 1 7 inclusive, in which the processor means includes encryption means for encrypting data captured by the camera.

19. A camera as claimed in any one of the preceding claims, which includes camera identification means for uniquely identifying the camera.

20. A camera as claimed in any one of the preceding claims, which includes security means for securing the camera against unauthorised use.

21 . A camera as claimed in Claim 20, in which the security means includes disabling means for selectively disabling operation of the camera.

22. A camera as claimed in any one of the preceding claims, which includes position detection means for detecting a rotational or angular position of the light sensing means.

23. A camera as claimed in Claim 22, in which the rotation means includes a motor having a drive shaft, and in which the position detection means includes a shaft encoder which is capable of generating pulses as the motor drive shaft is rotated.

24. A camera as claimed in Claim 23, in which the processor means includes simulation means for simulating the pulses, thereby simulating rotation of the light sensing means when it is in fact stationary.

25. A camera as claimed in Claim 24, in which the simulation means is capable of estimating a scanning frequency of the camera so that a single line of object data can be captured.

26. A camera as claimed in any one of the preceding claims, in which the processor means is capable of generating and transmitting a test pattern.

27. A panoramic camera system which includes at least one camera as claimed in any one of the preceding claims; and a monitoring facility which includes a personal computer with display operatively connected to the camera.

28. A system as claimed in Claim 27, in which the operative connection between the monitoring facility and the camera is via transmitters and cooperating receivers.

29. A system as claimed in Claim 27 or Claim 28, in which instructions to the camera to enter a stationary mode are sent from the monitoring facility to facilitate adjustment of camera optics.

30. A system as claimed in Claim C26, in which the simulation means is capable of transmitting a test pattern and the monitoring facility has receiving means for receiving the test pattern.

31 . A system as claimed in Claim 30, in which the test pattern is used for testing the operation of the processor means, the communication link, and its components.

32. A method of capturing images in a panoramic camera, the method including modifying light rays incident upon sensing means of the panoramic camera by means of an achromatic lens or reflector arrangement, thereby to enhance the far field resolution of the camera.

33. A method of capturing images in a panoramic camera, the method including selectively positioning at least one filter into an optical path of a lens arrangement of the camera.

34. A method as claimed in Claim 33, which includes the step of positioning a different filter in the optical path after a complete rotation of the light sensing means and the lens arrangement.

35. A method as claimed in Claim 33, which includes the step of changing the filter as a function of time.

36. A method as claimed in Claim 33, which includes the step of changing the filter in response to changing environmental conditions.

37. A method as claimed in Claim 32 or Claim 33, which includes the steps of receiving serial pixel data from each one of three sensor elements of the sensing means; and compensating the serial pixel data from two of the three sensor elements to produce pixel data including light sourced from a common object line.

38. A method as claimed in Claim 37, which includes feeding the output from each sensor element into an analog to digital converter; and delaying pixel data from two of the three sensor elements to provide a flow of parallel digital pixel data.

39. A method as claimed in Claim 38, which includes generating pulses as the drive shaft of the motor is rotated, the pulses being dependent on the position of the shaft and the angular velocity of the shaft; and using the pulses to clock pixel data from the light sensing means.

40. A method as claimed in Claim 39, which includes the steps of selectively holding the light sensing means stationary; and providing simulation means operable to simulate the pulses, to permit data to be clocked from the light sensing means.

41 . A new panoramic camera, substantially as herein described and illustrated.

42. A new panoramic camera system, substantially as herein described and illustrated.

43. A new method of capturing images in a panoramic camera, substantially as herein described and illustrated.