Abstract:
A system and method of identifying and locating one or more targets includes capturing one or more frames and recording position data for each of the frames. Each of the frames comprises a plurality of at least three different types of infrared image data. Each of the targets is identified and a location is provided based on the three different types of captured infrared image data in each of the frames and the recorded position data.

Description:
This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/541,189 filed Feb. 2, 2004 which is hereby incorporated by reference in its entirety. 
    
    
     This invention was developed with government funding from NASA under grant no. 30324 awarded on Sep. 10, 2002. The U.S. Government may have certain rights. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to image monitoring systems and, more particularly, to a target identification and location system for identifying and precisely locating one or more targets, such as a wildfire, and a method thereof. 
     BACKGROUND 
     Current wildfire detection and monitoring systems utilize multispectral line scanning sensors on aerial platforms. Examples of these types of systems include the MODIS Airborne Simulator (MAS) sensor demonstrated by NASA Ames on the ER-2 and the US Forest Service PHOENIX System flown on a Cessna Citation Bravo. These systems have demonstrated substantial utility in detecting and monitoring wildfires from airborne platforms. However, these systems are custom engineered from the “ground up” relying on custom design and fabrication of complex opto-mechanical servos, sensors, readout electronics and packaging. As a result, these systems are subject to malfunction and are difficult to service. 
     A typical fire detection mission scenario involves imaging a 10 km swath from an aircraft at 3 km altitude over an area of fire danger. Missions are usually conducted at night to reduce false alarms due to solar heating. Existing systems employ a line scanning, mid-wave infrared (MWIR) band as the primary fire detection band along with a long wave infrared (LWIR) band which provides scene context. By combining the MWIR and LWIR data, a hot spot detected by the MWIR band can be located with respect to ground features imaged in the LWIR band. The line scanner provides excellent band to band registration, but requires a complex rate controlled scanning mirror and significant post processing to correct for scan line to scan line variations in aircraft attitude and ground speed. These sensitive scanning mechanisms are also prone to failure and are difficult to service. While the location of the detected fires is shown in the image, there is no actual computation of a specific ground coordinate for each fire pixel. This requires a specially trained image interpreter to analyze each image and manually measure the latitude and longitude of each fire pixel. 
     SUMMARY OF THE INVENTION 
     A target identification and location system in accordance with embodiments of the present invention includes at least three different infrared imaging sensors, a positioning system, and an image data processing system. The image data processing system identifies and provides a location of one or more targets based on image data from the at least three different infrared cameras and positioning data from the positioning system. 
     A method of identifying and locating one or more targets in accordance with embodiments of the present invention includes capturing one or more frames and recording position data for each of the frames. Each of the frames comprises a plurality of at least three different types of infrared image data. Each of the targets is identified and a location is provided based on the three different types of captured infrared image data in each of the frames and the recorded position data. 
     The present invention provides a system and method for identifying and providing a precise location of one or more targets, such as a wildfire. More specifically, the present invention provides a significant increase in wildfire detection and monitoring capability, real time automated geo-location of a target, a significantly improved operational reliability and ease of use, and lower operating costs than with prior sensing systems. The present invention also has a lower false alarm rate than with prior fire sensing systems allowing reliable day and night operations 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a plane with a target identification and location system in accordance with embodiments of the present invention; 
         FIG. 2  is a block diagram of the target identification and location system shown in  FIG. 1 ; 
         FIG. 3  is a section of the plane shown in  FIG. 1  with a partial, perspective view of the supporting assemblies for the target identification and location system; 
         FIG. 4  is a perspective view of the gimbal assembly; 
         FIG. 5  is a side, partial cross-sectional view of the gimbal assembly shown in  FIG. 4 ; 
         FIG. 6  is a perspective view of an imaging system in the target identification and location system; 
         FIG. 7  is a table of specifications for one example of the target identification and location system; 
         FIG. 8  is a functional block diagram of a method for identifying a target in accordance with embodiments of the present invention; 
         FIG. 9  is a functional block diagram of a method for detecting a target in accordance with embodiments of the present invention; and 
         FIG. 10  is a graph of multi-spectral images to discriminate a fire from a solar reflection. 
     
    
    
     DETAILED DESCRIPTION 
     A target identification and location system  10  in accordance with embodiments of the present invention in an aircraft  15  is illustrated in  FIGS. 1-6  and  8 . The target identification and location system  10  includes an imaging system  11  with a LWIR imaging sensor  12 , a MWIR imaging sensor  14 , a short wave infrared (SWIR) imaging sensor  16 , a very near infrared (VNIR) imaging sensor  18 , a global positioning system  20 , an inertial measurement system  22 , and an image data processing system  24 , although the target identification and location system  10  can include other types and numbers of components connected in other manners. The present invention provides a system  10  and method for identifying and providing a precise location of one or more targets, such as a wildfire. More specifically, the present invention provides a significant increase in wildfire detection and monitoring capability, real time automated geo-location of a target, a significantly improved operational reliability and ease of use, and lower operating costs than with prior sensing systems. 
     Referring to FIGS.  1  and  3 - 5 , the target identification and location system  10  is mounted in an electronics rack assembly  26  and a sensor mounting system  28  in an aircraft  15 , although the target identification and location system  10  can be mounted with other types of mounting systems and in other types of vehicles. The electronics rack assembly  26  is used to secure the image data processing system  10  in the aircraft, although the image data processing systems could be secured in other manners in other locations. The sensor mounting system  28  is mounted to a floor  30  of the aircraft  15  above an opening or window, although the sensor mounting system  28  could be mounted on other surfaces in other locations, such as on the outside of the aircraft  15 . 
     The sensor mounting assembly  28  includes a single axis positioning assembly  32 , such as a gimbal assembly, that supports and allows for pivotal motion of the imaging system  11  about a first axis A-A, although other types of mounting systems for the single axis positioning assembly could be used. The single axis positioning system  32  allows the line of sight of the LWIR imaging sensor  12 , the MWIR imaging sensor  14 , the SWIR imaging sensor  16 , the VNIR imaging sensor  18  in the imaging system  11  to pivot to provide a wide field of view for imaging the ground. In this particular embodiment, the lines of sight of the LWIR imaging sensor  12 , the MWIR imaging sensor  14 , the SWIR imaging sensor  16 , the VNIR imaging sensor  18  can be pivoted across a swath +/−40 degrees for a total imaging swath of +/−60 degrees (taking into account the 40 degree field of view for each imaging sensor  12 ,  14 ,  16 , and  18 ), although the lines of sight can be pivoted other amounts and the imaging sensors could have other ranges for the field of view. 
     Referring to  FIGS. 1-3 ,  5 ,  6 , and  8 , the imaging system  11  includes LWIR imaging sensor  12 , the MWIR imaging sensor  14 , the SWIR imaging sensor  16 , the VNIR imaging sensor  18  which are each used to capture infrared images or infrared image data for target identification and location to provide a location of the one or more targets, although the imaging system  11  can include other types and numbers of imaging sensors, such as a visible imaging sensor  19  for capturing one or more visible images in each of the frames. In this particular embodiment, the spectral ranges for the LWIR imaging sensor  12  is about 8.0-9.2 microns, the spectral range for the MWIR imaging sensor  14  is about 3.0-5.0 microns, the spectral range for the SWIR imaging sensor  16  is about 0.9-1.7 microns, and the spectral range for the VNIR imaging sensor  18  is about 0.4-0.9 microns, although the imaging sensors could have other spectral ranges which are either spaced apart or partially overlap and other types of imaging sensors can be used. The LWIR imaging sensor  12 , the MWIR imaging sensor  14 , the SWIR imaging sensor  16 , the VNIR imaging sensor  18  are large area format camera systems, instead of line scanning imaging systems, although systems with other types of formats can be used. The imaging system  11  transmits data about the captured image data to the image data processing system  24  via an image interface system  34 . 
     Referring to  FIGS. 2 ,  3 , and  8 , the global positioning system  20  and the inertial measurement system  22  are mounted to the sensor mounting assembly, although other types and numbers of positioning systems can be used. The global positioning system  20  includes provides precise positioning data and the inertial measurement system provides inertial measurement data about each of the frames of captured image data by the imaging system  11  to a position processor  36 . The global positioning system  20  also provides precise data about the line of sight of the cameras. Additionally, a precision encoder and drive motor system  38  is mounted to a drive axis A-A for the single axis positioning system  32  and provides position data about the imaging system  11  to the position processor  36 . The position processor  36  determines the precise location of each of the frames of image data based on position data from the global positioning system  20 , the inertial measurement system  22 , and the precision encoder and drive motor system  38  and transmits the locations to the image data processing system  24 , although the location can be determined by other systems, such as the image data processing system  24 . 
     The data image processing system  24  includes a central processing unit (CPU) or processor  40 , a memory  42 , an input device  44 , a display  46 , and an input/output interface system  48  which are coupled together by a bus or other communication link  50 , although other types of processing systems comprising other numbers and types of components in other configurations can be used. The processor  40  executes a program of stored instructions for one or more aspects of the present invention as described herein, including a method for identifying and providing a precise location for the one or more targets as described and illustrated herein. 
     The memory  42  stores the programmed instructions for one or more aspects of the present invention as described herein including the method identifying and providing a precise location for the one or more targets as described herein, although some or all of the programmed instructions could be stored and/or executed elsewhere. The memory  42  also stores calibration and correction tables for each of the imaging sensors  12 ,  14 ,  16 ,  18 , and  19  in the imaging system  11  in tables. A Digital Elevation Model (DEM) is also stored in memory  42  and is used to provide terrain elevation information which will be used by the processor  40  for precise geo-location of the imagery. Additionally, vector data from a geospatial information system (GIS), such as roads, water bodies and drainage, and other manmade and natural landscape features I stored in memory  42  and will be used in the processor  40  to combine with or annotate the imagery. Other data sets stored in memory  42  may include relatively low resolution imagery from sources such as LANDSAT that would be used by the processor  40  to provide overall scene context. A variety of different types of memory storage devices, such as a random access memory (RAM) or a read only memory (ROM) in the system or a floppy disk, hard disk, CD ROM, or other computer readable medium which is read from and/or written to by a magnetic, optical, or other reading and/or writing system that is coupled to the processor, can be used for memory  42  to store the programmed instructions described herein, as well as other information. 
     The input device  44  enables an operator to generate and transmit signals or commands to the processor  40 . A variety of different types of input devices can be used for input device  44 , such as a keyboard or computer mouse. The display  44  displays information for the operator. A variety of different types of displays can be used for display  44 , such as a CRT display. The input/output interface system  48  is used to operatively couple and communicate between the image data processing system  24  and other devices and systems, such as the LWIR imaging sensor  12 , MWIR imaging sensor  14 , SWIR imaging sensor  16 , VNIR imaging sensor  18 , global positioning system  20 , inertial measurement system  22 , and precision encoder and drive motor system  38 . A variety of communication systems and/or methods can be used, such as a direct connection, a local area network, a wide area network, the world wide web, modems and phone lines, and wireless communication technology each having their own communications protocols. 
     By way of example only, a table of specifications for one example of the target identification and location system  10  is shown in  FIG. 7 , although the target identification and location system  10  can be configured to have other specifications. Also, by way of example only, the weight of the target identification and location system  10  is estimated to be less than 220 lb and maximum operating power less than 550 W. As a result, the present invention weighs less and uses less power than prior systems. 
     The operation of the target identification and location system  10  in accordance with embodiments of the present invention will now be described with reference to  FIGS. 1-6  and  8 - 10 . The target identification and location system  10  in the aircraft  15  collects a mosaic of frames across a full swath by “stepping” the line of sight of the imaging system  11  across the swath using the single-axis positioning system  32  with the drive motor and position encoder system  38 . The drive motor and position encoder system  32  steps the imaging system  11  through different positions about the axis A-A and transmits the position data about the imaging system  11  for each positions of each frame of the captured image data to the image data processing system  24 . After a full swath of image data is acquired, the single-axis positioning system  32  resets the line of sight of the imaging system  11  to complete the cycle. By way of example only, a full swath is acquired in about eight seconds and typically no more than seventeen seconds, although other amounts of time to collect a full swath can be used. As a result, the present invention does not need complex and expensive rate controlled servo mechanisms to capture frames, since each frame is captured from a static position. 
     In these embodiments, four frames are acquired by the imaging system  11  over the swath which covers an area of up to 10 km, although other numbers of frames can be acquired over other areas. The imaging system  11  captures each of the four frames across the swath using at least three of the LWIR imaging sensor  12 , MWIR imaging sensor  14 , SWIR imaging sensor  16 , and VNIR imaging sensor  18  to capture image data in three spectral bands, although other numbers and types of imaging sensors can be used and other spectral bands can be acquired. To accurately identify one or more targets, such as wildfires, the present invention acquires image data in LWIR, MWIR, and SWIR bands during nighttime hours and acquires image data in LWIR, MWIR, SWIR, and VNIR bands during daylight. With respect to the image data which is acquired, the image data processing system  24  retrieves calibration and correction data from tables stored in memory  42  for each of the imaging sensors  12 ,  14 ,  16 , and  18  in the imaging system  11  and makes adjustments to the captured image data based on the retrieved calibration and correction data. 
     Next, the image data processing system  24  with the position processor  36  performs geo-referencing and registration on the corrected and calibrated image data. The global positioning system  20 , the inertial measurement system  22 , and the drive motor and encoder system  38  provide the image data processing unit  24  and the position processor  36  with the global position data, inertial measurement data, and imaging system  11  positioning data, respectively, for each frame of the corrected and calibrated image data, although other positioning data could be provided. The image data processing system  24  with the position processor  36  also receive data about the operating parameters of the aircraft  15  at the time the frames of image data are captured. As the aircraft  15  moves while collecting the full swath, there is a slight in-track offset from frame to frame of about 61 pixels (12% of the image), although the offset can vary depending on the operating characteristics of the aircraft  15 , for example the speed of the aircraft  15 . The motion of the aircraft  15  will also produce less than 0.5 pixel of image motion smear during a nominal 15 ms integration time at a nominal ground speed of 180 knots, although the smear will also vary depending on the operating characteristics of the aircraft  15 . The image data processing system  24  with the position processor  36  use the obtained position data and the data related to the slight in-track offset and the image motion smear to adjust the image data in each of the frames. The image data processing system  24  with the position processor  36  obtains a precise measurement of the orientation and position of each imaging sensor  12 ,  14 ,  16 , and  18  for each frame of imagery. The position processor  36  utilizes data from a combination of a precision GPS  20  and an inertial measurement unit  22 . The image data processing system  24  combines the measured image sensor position and orientation data with known camera internal orientation geometry and the DEM using photogrammetric techniques to calculate a fully corrected image for each frame. 
     The image data processing system  24  performs a two step registration process on the image data from the imaging system  11  for each of the frames to create a substantially full swath mosaic. First, the image data processing system  24  performs a band to band registration which aligns the image data for the three different captured bands for each frame into one frame. Next, the image data processing system  24  performs a frame to frame registration which produces a full swath mosaic. By way of example, the image data processing system  24  may use a method for frame to frame registration, such as the method and apparatus for mapping and measuring land disclosed in U.S. Pat. No. 5,247,356, which is herein incorporated by reference in its entirety. The relative alignment of each of the image sensors  12 ,  14 ,  16 , and  18  is calculated through a pre-operation calibration process in which the image sensors  12 ,  14 ,  16 , and  18  simultaneously image a known set of ground or laboratory targets. The relative offsets and rotations are determined from this image set and programmed into the processor  40 . 
     Next, the image data processing system  24  processes the image data to identify and discriminate a target, such as a wildfire, from other items. Typical processing by processor  40  may include the calculation of a ratio of apparent brightness for each pixel and comparing that to a pre-determined threshold. The inclusion of a third spectral band allows the application of more sophisticated algorithms than would be possible using only two bands. One example of this processing is illustrated in  FIG. 10  where image data from LWIR imaging sensor  12 , the MWIR imaging sensor  14 , the SWIR imaging sensor  16 , and the visible imaging sensor  19  to identify and discriminate a wildfire from a solar reflection. 
     Next, the image data processing system  24  generates an output, such as an annotated map, on the display  46  to identify the type and location of the target(s), although other types of displays could be generated or stored for later use. To add information value to the displayed imagery, relevant GIS vector data may be inserted as an overlay. Low resolution data, for example RGB LANDSAT data, may be displayed alongside LWIR data to provide a visible context to the imagery. 
     The present invention provides a system and method for identifying and providing a precise location of one or more targets, such as a wildfire. In particular, the present invention provides the wildfire management community with the capability to detect and monitor wildfires from either manned or UAV aerial platforms. The present invention extends the operational envelope into the daytime and also improves operability. The extension of mission capability into the daylight hours is enabled by the use of a SWIR imaging sensor  16  in addition to the bands provided by the MWIR imaging sensor  14  and the LWIR imaging sensor  12 . The SWIR imaging sensor  16  helps to discriminate fire targets in daylight and also for detecting hot fires at night. 
     A very high resolution visible imaging sensor  19  can be used with the imaging system  11  to provide detailed scene context during daylight operations for each of the captured frames. The visible imaging sensor  19  would capture image data with the three or more of the LWIR imaging sensor  12 , MWIR imaging sensor  14 , SWIR imaging sensor  16 , and VNIR imaging sensor  18  which are capturing image data. As a result, the present invention can not only identify and provide the location of one or more targets, but also can also provide a visible image of each of the targets. Use of a high resolution visible imaging sensor  19  also provides excellent spatial context and improves the frame registration process. 
     Having thus described the basic concept of the invention, it will be rather apparent to those skilled in the art that the foregoing detailed disclosure is intended to be presented by way of example only, and is not limiting. Various alterations, improvements, and modifications will occur and are intended to those skilled in the art, though not expressly stated herein. These alterations, improvements, and modifications are intended to be suggested hereby, and are within the spirit and scope of the invention. Additionally, the recited order of processing elements or sequences, or the use of numbers, letters, or other designations therefor, is not intended to limit the claimed processes to any order except as may be specified in the claims. Accordingly, the invention is limited only by the following claims and equivalents thereto.