46 results about "Perspective camera" patented technology

A catadioptric camera having a perspective camera and multiple curved mirrors, images the multiple curved mirrors and uses the epsilon constraint to establish a vertical parallax between points in one mirror and their corresponding reflection in another. An ASIFT transform is applied to all the mirror images to establish a collection of corresponding feature points, and edge detection is applied on mirror images to identify edge pixels. A first edge pixel in a first imaged mirror is selected, its 25 nearest feature points are identified, and a rigid transform is applied to them. The rigid transform is fitted to 25 corresponding feature points in a second imaged mirror. The closes edge pixel to the expected location as determined by the fitted rigid transform is identified, and its distance to the vertical parallax is determined. If the distance is not greater than predefined maximum, then it is deemed correlate to the edge pixel in the first imaged mirror.

This invention provides a system and method for determining correspondence between camera assemblies in a 3D vision system implementation having a plurality of cameras arranged at different orientations with respect to a scene involving microscopic and near microscopic objects under manufacture moved by a manipulator, so as to acquire contemporaneous images of a runtime object and determine the pose of the object for the purpose of guiding manipulator motion. At least one of the camera assemblies includes a non-perspective lens. The searched 2D object features of the acquired non-perspective image, corresponding to trained object features in the non-perspective camera assembly can be combined with the searched 2D object features in images of other camera assemblies, based on their trained object features to generate a set of 3D features and thereby determine a 3D pose of the object.

A method and a system for self-calibrating a wide field-of-view camera (such as a catadioptric camera) using a sequence of omni-directional images of a scene obtained from the camera. The present invention uses the consistency of pairwise features tracked across at least a portion of the image collection and uses these tracked features to determine unknown calibration parameters based on the characteristics of catadioptric imaging. More specifically, the self-calibration method of the present invention generates a sequence of omni-directional images representing a scene and tracks features across the image sequence. An objective function is defined in terms of the tracked features and an error metric (an image-based error metric in a preferred embodiment). The catadioptric imaging characteristics are defined by calibration parameters, and determination of optimal calibration parameters is accomplished by minimizing the objective function using an optimizing technique. Moreover, the present invention also includes a technique for reformulating a projection equation such that the projection equation is equivalent to that of a rectilinear perspective camera. This technique allows analyses (such as structure from motion) to be applied (subsequent to calibration of the catadioptric camera) in the same direct manner as for rectilinear image sequences.

This invention provides a system and method for training and performing runtime 3D pose determination of an object using a plurality of camera assemblies in a 3D vision system. The cameras are arranged at different orientations with respect to a scene, so as to acquire contemporaneous images of an object, both at training and runtime. Each of the camera assemblies includes a non-perspective lens that acquires a respective non-perspective image for use in the process. The searched object features in one of the acquired non-perspective image can be used to define the expected location of object features in the second (or subsequent) non-perspective images based upon an affine transform, which is computed based upon at least a subset of the intrinsics and extrinsics of each camera. The locations of features in the second, and subsequent, non-perspective images can be refined by searching within the expected location of those images. This approach can be used in training, to generate the training model, and in runtime operating on acquired images of runtime objects. The non-perspective cameras can employ telecentric lenses.

A paraboloidal catadioptric camera is calibrated by relaxing the assumption of an ideal system to account for perspective projection, radial distortion, and mirror misalignment occurring within the camera system. Calibration points, which are small and visually distinct objects, are distributed at fixed locations within an environment. Omnidirectional images are captured by the catadioptric camera at different locations of the environment. Data points are obtained by identifying the location of the calibration points in each captured image. An optimization algorithm best-fits the data points to a perspective camera model in order to derive parameters, which are used to calibrate the catadioptric camera.

The invention discloses a single-chart self-calibration method of a catadioptric omnibearing camera mirror plane pose, comprising the following steps: firstly, calculating to obtain two candidate poses by using an ellipse fit by image points on the outer edge of the mirror plane in a collected image; respectively generating two groups of predicted formed images of the edge of a perspective camera by the two candidate poses; and comparing the two groups of predicted formed images with a practical lens formed image, wherein a candidate pose corresponding to the predicated formed image with small difference is a practical mirror plane pose, and necessary distance between a camera projection center and a practical lens edge in the calibration process is obtained by using an optimized search method. By using the method, the deficiency of the existing calibration method is overcome; under the condition that the mirror plane parameter and the perspective camera parameter are known, a rotary matrix and a translation vector between a reflection mirror surface and the perspective camera can be estimated only by one self-shooting image of the catadioptric omnibearing camera without other calibration objects. The calibration method has the characteristics of strong anti-interference performance and higher precision and is simple to operate.

The invention discloses a new single camera based omnibearing stereo vision system. The system is characterized in that the system comprises a transparent cylinder, upper and lower reflecting mirror surfaces in specific shapes and a perspective camera, wherein an upside mirror surface is a combined mirror surface of two of a hyperboloid, an ellipsoid, a paraboloid and a plane mirror; a downside mirror surface is a hyperboloid or a paraboloid; the perspective camera is installed inside the downside mirror surface; the main optical axis of the perspective camera is coaxial with the principal axis of the upper and lower reflecting mirror surfaces and the lens of the perspective camera is slightly smaller than the aperture at the top of the downside mirror surface; one part of the combined mirror surface forms images independently and the other part of the combined mirror surface forms a foldback system with the downside mirror surface; and two images of an object are formed on a camera and the corresponding image points are on the rays with the centers of the images as the circle centers. The system has the following advantages: the system is compact in structure and is light and small; the horizontal 360-degree and vertically bidirectionally-angled three-dimensional viewing field can be formed; and the stereo vision information is convenient to obtain by adopting the depth recovery algorithm.

The invention belongs to the field of machine vision, and particularly relates to a hybrid vision target positioning method based on panoramic vision and conventional vision. The method comprises the following steps: (1) calibrating a hybrid vision system; (2) identifying a target by a panorama camera, calculating the azimuth angle of a target in a panoramic image, causing a perspective camera to rotate at a corresponding angle, and shooting the target identified by the perspective camera; (3) adopting a SIFT (Scale Invariant Feature Transform) image feature point matching algorithm to match feature points in the common field of view of the hybrid vision system; and (4) calculating the three-dimensional information of the identified target, and positioning the target. By use of the method, the hybrid vision system is used, the advantage of the high resolution of the perspective camera is applied on a premise of guaranteeing the advantage of large visual field video monitoring of a panoramic vision system to position the target, positioning accuracy is improved, and therefore, a stereo visual target detection system with low power consumption and high performance is realized.

The invention discloses a panoramic video rendering method, and the method comprises the steps: obtaining a current frame image from a video source, generating texture mapping data, determining a gazepoint region according to the visual angle of a perspective camera, and generating texture mapping data; rendering the picture pixels outside the fixation point area by adopting a resolution lower than that of the picture pixels in the fixation point area; constructing a spherical rendering model, and mapping the current frame image into a three-dimensional picture according to the texture mapping data; and projecting the three-dimensional picture into a two-dimensional screen. The invention further discloses a panoramic video rendering system, an electronic device and a computer readable storage medium. Therefore, the rendering efficiency can be optimized and the playing lag can be avoided by weakening the rendering mode of the picture pixels outside the user fixation point area.

This invention provides a system and method for determining correspondence between camera assemblies in a 3D vision system implementation having a plurality of cameras arranged at different orientations with respect to a scene, so as to acquire contemporaneous images of a runtime object and determine the pose of the object, and in which at least one of the camera assemblies includes a non-perspective lens. The searched 2D object features of the acquired non-perspective image, corresponding to trained object features in the non-perspective camera assembly, can be combined with the searched 2D object features in images of other camera assemblies (perspective or non-perspective), based on their trained object features to generate a set of 3D image features and thereby determine a 3D pose of the object. In this manner the speed and accuracy of the overall pose determination process is improved. The non-perspective lens can be a telecentric lens.

The present invention relates to a VIVE virtual earth roaming browse method based on an OsgEarth. The method comprises the steps of: Based on an OsgEarth digital earth platform, constructing a three-dimensional geographic information scene; based on the OpenVR, constructing a plugin suitable for an OsgEarth digital earth platform; employing the plugin suitable for the OsgEarth digital earth platform, performing arrangement and connection of an HTC VIVE hardware device; and employing a camera controller with a first-person perspective and employing the HTC VIVE to perform roam control on the OsgEarth digital earth. Through combination of the OpenVR technology and the OsgEarth technology, the link of the HTC VIVE hardware device and the OsgEarth software platform is constructed, and the OsgEarth digital earth platform VR roam first-person perspective camera controller is constructed through the coordinate transformation relation among the real space, the virtual space, the projection space and the device space so as to achieve the global VR roam browse control function, and the VIVE virtual earth roaming browse method based on an OsgEarth is vivid in effect, high in sense of realityand convenient to operate and use, and can be widely applied to the geographic information application field.

The invention discloses a dynamic image fusion method and system for VR panoramic live broadcast, and the method comprises the steps: collecting a multi-view live broadcast stream, carrying out compression coding, and pushing the multi-view live broadcast stream to a streaming media server in real time; using a dynamic image fusion algorithm to seamlessly splice the live broadcast images of different visual angles to generate VR panoramic live broadcast streams; creating a virtual scene and a 3D sphere object, and establishing a grid model in the virtual scene by taking the VR panorama as a material; creating a virtual perspective camera, and specifying an initial position, a direction and a visual field range of the camera; creating a 3D renderer, rendering all the two-dimensional live broadcast pictures in the visual field range of the virtual camera in the scene into a three-dimensional image, and displaying the three-dimensional image; and changing the position and direction of thevirtual camera according to the change of the viewing angle of the user so as to generate and display live broadcast pictures of different viewing angles. According to the invention, the visual anglechange of the user is supported, the visual field range of the user in live broadcast can be expanded, the live broadcast blind area is eliminated, immersive visual perception is brought to the user,and the live broadcast effect is improved.

The invention discloses a method for expanding N-surface perspective panoramic images of an omni-directional camera, which is based on Taylor series models. The method comprises the following steps that: the omni-directional camera is calibrated by use of a Taylor series model, so as to obtain internal parameters of the camera; the size of an N-surface perspective panoramic image is estimated; and re-projection and interpolation are carried out so as to obtain the N-surface perspective panoramic image. The method is applicable to various omni-directional vision sensors, has the characteristic of wide application range, and can obtain parameters through calibration under the condition that the parameters of the omni-directional vision sensors are unknown and carry out effective panoramic image expansion. Every surface in the generated N-surface perspective panoramic image is equivalent to an image generated by a common perspective camera, thereby ensuring that the application of the prior algorithm applied to the prior perspective camera can be continued.

The invention provides an airborne panoramic rotor pyramidal angle measurement device, which consists of a framing module, a perspective imaging module, a protective module and a panoramic image embedded treatment module, wherein the framing module is connected with the protective module through a connector; the protective module is connected and fixedly arranged on a rotor hub through a flange; the perspective imaging module and the panoramic image embedded treatment module are arranged in the protective module; the framing module comprises a hyperboloidal mirror arranged in a protective glass tube and a hyperboloidal mirror connector arranged on the top end of the protective glass tube; the perspective imaging module consists of a high-frame rate scientific-grade camera, a perspective camera and a Cameralink video transmission line; and the panoramic image embedded treatment module consists of a Cameralink viceo input and output interface, an image processing unit and a data output interface. The measurement device has the characteristics of simplicity of structure, convenience for regulation, simplicity and quickness of installation and maintenance, operation stability and reliability, and is used for helicopter rotor pyramidal angle measurement.

The invention relates to a terahertz (THz) video camera for channel security check, which comprises a Stirling refrigeration thermoelectric planar array THz camera and a solid THz remote radiation source of which the section of a semiconductor laser optical pump is a lithium niobate crystal bar, wherein the Stirling refrigeration thermoelectric planar array THz camera and the solid THz remote radiation source of which the section of the semiconductor laser optical pump is the lithium niobate crystal bar are used for aiming at a channel to perform reflection-type THz vision-assistance camera shooting or shooting oppositely by aiming at the channel to perform THz camera shooting. The THz video camera for the channel security check has the performances of improving the emergence energy of THz radials and the THz imaging quality by a fully tap cooperation potential. The THz video camera for realizing real-time channel security check by aiming at the specific application of the channel security check and the THz perspective camera shooting feature can be powered up in the field to work for a long time, is convenient in use, has long service life and can achieve the goals of the invention.

A catadioptric camera having a perspective camera and multiple curved mirrors, images the multiple curved mirrors and uses the epsilon constraint to establish a vertical parallax between points in one mirror and their corresponding reflection in another. An ASIFT transform is applied to all the mirror images to establish a collection of corresponding feature points, and edge detection is applied on mirror images to identify edge pixels. A first edge pixel in a first imaged mirror is selected, its nearest feature points are identified, and a rigid transform is applied to them. The rigid transform is fitted to corresponding feature points in a second imaged mirror. The closest edge pixel to the expected location as determined by the fitted rigid transform is identified, and its distance to the vertical parallax is determined. If the distance is not greater than predefined maximum, then it is deemed correlate to the edge pixel in the first imaged mirror.

The invention discloses a posture judgment method and device. According to the posture judgment method, posture judgment is performed by adopting a reading robot, and the reading robot is provided with a perspective camera which is used for collecting images of a to-be-judged object. The method comprises the steps of obtaining the images of the to-be-judged object by utilizing the camera, whereinthe images at least include spine picture information of the to-be-judged object; pretreating the images so as to obtain posture information; extracting position information of a plurality of joints of spines of the to-be-judged object from the posture information, and connecting the adjacent joints in sequence according to the position information so as to obtain a joint curve; comparing the joint curve with a prestored standard joint curve so as to obtain a comparison result; judging whether the posture is standard according to the comparison result; and performing the preset reminding operation if the posture is not standard, so that whether the posture is standard can be accurately judged.

The invention puts forward a face fitting method based on a three-dimensional deformation model. The method comprises the main contents of the three-dimensional deformation model, scaled orthographicprojection, a perspective camera model and a shape from a sign. The method comprises the process that: firstly, from a shape parameter, determining the vertex position of the three-dimensional deformation model, wherein the shape is described by a linear subspace model in data via principal component analysis; then, using an axial vector to carry out parameterization on a rotation matrix, enablingan interval space to be constant, and simulating calibration lacking information; finally, assuming that the sign corresponds to the vertex in the deformation model, finding a shape, a gesture and acamera parameter, and minimizing the sum of squared distances on all signs; and importing target functions under an orthographic and perspective situation, and expressing the target functions as a separable nonlinear least square problem. By use of the method, the model is fit to server as the separable nonlinear least square problem, one series of problems brought by light, shape shielding and the like can be solved, the calibration lacking information is effectively simulated, and face fitting is quick and accurate.

The invention discloses a same-axis-center-distance equal-optical-flow catadioptric camera distance measurement system and a distance measurement method thereof. A center symmetry axis of a rotating body mirror plane and the optical axis of a perspective camera are collinear and have a fixed distance; a measured object is placed below the rotating body mirror plane, incident light of a measured object space point is reflected through the mirror plane and then imaged to the perspective camera, and the rotating body mirror plane has a mirror plane contour with an equal-optical-flow characteristic. The method comprises the steps: firstly building a simulation environment, and setting system parameters to obtained a relational expression between the axis center distance and the optical flow value; then actually measuring the distance, and after the camera acquires an image, calculating the optical flow value of the measured object space point at an imaged position on a camera imaging plane; and calculating the axis center distance from the measured object space point to the camera optical axis by using the relational expression, and thus achieving the distance measurement. With utilization of the equal-optical-flow characteristic of the rotating body mirror plane, the corresponding relationship is formed among the measured object space point, the camera optical axis and the optical flow, and thus the distance of a scene can be directly measured; and the system and the method can be used for unmanned aerial vehicle navigation and collision avoidance, and detect the height to the ground and the distance to obstacles.

The invention discloses a method for calibrating parameters of an identical-axis-distance equal-luminous-flux catadioptric camera distance measuring system. According to the method, a central symmetrical axis of a rotary body mirror face is collinear with an optical axis of a perspective camera, a to-be-measured object is arranged below the rotary body mirror face, incidence light is reflected by the mirror face to be imaged by the perspective camera, and the rotary body mirror face has a mirror face profile with equal-luminous-flux characteristic. The method comprises the following steps of establishing a plurality of different simulation environments by adopting the camera distance measuring system, gradually increasing the distance from a to-be-measured object spatial point in each simulation environment to the optical axis, respectively acquiring luminous flux of the to-be-measured object spatial point in each simulation environment on an acquisition image of the perspective camera, and re-fitting the relation between the axis distance and the luminous flux. According to the method, the system is subjected to the parameter calibration, the influence of the processing precision and installation precision on the characteristics of the mirror face can be alleviated under the non-ideal configuration situation of the system, and the distance measuring precision can be improved. Compared with the traditional external parameter calibration method, the method is simpler, more convenient and more effective.

The invention discloses a printed matter quality test device. The test device is arranged at a position corresponding to a chain of a bi-color ink recorder for forming a test point for the quality of printed matter, the test device comprises a camera assembly, a perspective camera, a light source and an air-drafting and flattening device, the chain is composed of a first arc segment, a second arc segment, a third arc segment, a first straight-line segment, a second straight-line segment and a third straight-line segment, the test point is arranged at a climbing position corresponding to the second straight-line segment of the chain, the camera assembly and the air-drafting and flattening device are arranged at the two sides of the chain corresponding to the test point respectively, the light source and the camera assembly are arranged at the same side, and the perspective camera and the air-drafting and flattening device are arranged at the same side. According to the printed matter quality test device, the test point is arranged at the position corresponding to the chain of the bi-color ink recorder, the imaging problem that in an existing bi-color ink recorder, a test device cannot be arranged at the position of an impression cylinder but is arranged on a collection portion is effectively solved, imaging stability is greatly improved, and the false alarm rate is lowered.

The invention aims to provide a method and equipment for generating a fisheye camera image. The method comprises steps of determining scene coordinates corresponding to one or more pixels based on theplurality of perspective camera images and the corresponding depth camera images, and determining corresponding fisheye imaging coordinates of each pixel on the imaging plane according to the scene coordinates corresponding to each pixel and the coordinate corresponding relationship, and generating a corresponding fisheye camera image based on each pixel and the fisheye imaging coordinates thereof. According to the invention, the fisheye camera image with the large FOV can be generated based on the plurality of perspective camera images with the small FOV.

The invention relates to an intelligent military infrared light vision cloud mirror, comprising a main body, an infrared perspective camera lens and a recorder camera lens arranged on the front surface of the main body, and a control interface arranged on the back surface of the main body, wherein angle adjustment mechanisms are arranged at two ends of the recorder camera lens respectively, each angle adjustment mechanism comprises a driving component and a steering shaft, and one end of the steering shaft is fixed with the recorder camera lens, while the other end of the steering shaft is in transmission connection with the driving component; the intelligent military infrared light vision cloud mirror controls a driven gear to rotate via a driving gear, then the steering shaft can be controlled to rotate, thus the up-down rotation of the recorder camera lens is achieved; meanwhile, the driving gear can be limited by four limiting components in an annular groove, so that the angle adjustment reliability of the recorder camera lens is improved; and besides, when fixing blocks are installed into the annular groove, the fixing blocks can be embedded into the annular groove by raising springs and balls, the flexibility in the assembly and the disassembly of the limiting units is improved, and the practicability of the device is enhanced.

The invention discloses a method for calibrating parameters of an identical-axis-distance equal-luminous-flux catadioptric camera distance measuring system. According to the method, a central symmetrical axis of a rotary body mirror face is collinear with an optical axis of a perspective camera, a to-be-measured object is arranged below the rotary body mirror face, incidence light is reflected by the mirror face to be imaged by the perspective camera, and the rotary body mirror face has a mirror face profile with equal-luminous-flux characteristic. The method comprises the following steps of establishing a plurality of different simulation environments by adopting the camera distance measuring system, gradually increasing the distance from a to-be-measured object spatial point in each simulation environment to the optical axis, respectively acquiring luminous flux of the to-be-measured object spatial point in each simulation environment on an acquisition image of the perspective camera, and re-fitting the relation between the axis distance and the luminous flux. According to the method, the system is subjected to the parameter calibration, the influence of the processing precision and installation precision on the characteristics of the mirror face can be alleviated under the non-ideal configuration situation of the system, and the distance measuring precision can be improved. Compared with the traditional external parameter calibration method, the method is simpler, more convenient and more effective.

The invention relates to an intelligent military infrared night vision cloud mirror, comprising a main body, an infrared perspective lens and a recorder lens arranged on the front of the main body, and a control interface arranged on the back of the main body; the two ends of the recorder lens are respectively provided with angle adjustment mechanism, the angle adjustment mechanism includes a drive assembly and a steering shaft, one end of the steering shaft is fixed to the lens of the recorder, and the other end of the steering shaft is connected to the drive assembly, and the intelligent military infrared night vision cloud mirror is driven The gear controls the rotation of the driven gear, and then it can control the rotation of the steering shaft, realizing the up and down rotation of the recorder lens; at the same time, the drive gear can be limited by the four limit components in the annular groove, which improves the recorder lens. The reliability of angle adjustment; not only that, when the fixed block is installed in the annular groove, the spring and the ball can be embedded in the annular groove on the fixed block, which improves the flexibility of loading and unloading of the limit unit and improves the practicality of the equipment. sex.

The invention provides an airborne panoramic rotor pyramidal angle measurement device, which consists of a framing module, a perspective imaging module, a protective module and a panoramic image embedded treatment module, wherein the framing module is connected with the protective module through a connector; the protective module is connected and fixedly arranged on a rotor hub through a flange; the perspective imaging module and the panoramic image embedded treatment module are arranged in the protective module; the framing module comprises a hyperboloidal mirror arranged in a protective glass tube and a hyperboloidal mirror connector arranged on the top end of the protective glass tube; the perspective imaging module consists of a high-frame rate scientific-grade camera, a perspective camera and a Cameralink video transmission line; and the panoramic image embedded treatment module consists of a Cameralink viceo input and output interface, an image processing unit and a data output interface. The measurement device has the characteristics of simplicity of structure, convenience for regulation, simplicity and quickness of installation and maintenance, operation stability and reliability, and is used for helicopter rotor pyramidal angle measurement.

The invention discloses a single-chart self-calibration method of a catadioptric omnibearing camera mirror plane pose, comprising the following steps: firstly, calculating to obtain two candidate poses by using an ellipse fit by image points on the outer edge of the mirror plane in a collected image; respectively generating two groups of predicted formed images of the edge of a perspective cameraby the two candidate poses; and comparing the two groups of predicted formed images with a practical lens formed image, wherein a candidate pose corresponding to the predicated formed image with small difference is a practical mirror plane pose, and necessary distance between a camera projection center and a practical lens edge in the calibration process is obtained by using an optimized search method. By using the method, the deficiency of the existing calibration method is overcome; under the condition that the mirror plane parameter and the perspective camera parameter are known, a rotary matrix and a translation vector between a reflection mirror surface and the perspective camera can be estimated only by one self-shooting image of the catadioptric omnibearing camera without other calibration objects. The calibration method has the characteristics of strong anti-interference performance and higher precision and is simple to operate.

This invention provides a system and method for training and performing runtime 3D pose determination of an object using a plurality of camera assemblies in a 3D vision system. The cameras are arranged at different orientations with respect to a scene, so as to acquire contemporaneous images of an object, both at training and runtime. Each of the camera assemblies includes a non-perspective lens that acquires a respective non-perspective image for use in the process. The searched object features in one of the acquired non-perspective image can be used to define the expected location of object features in the second (or subsequent) non-perspective images based upon an affine transform, which is computed based upon at least a subset of the intrinsics and extrinsics of each camera. The locations of features in the second, and subsequent, non-perspective images can be refined by searching within the expected location of those images. This approach can be used in training, to generate the training model, and in runtime operating on acquired images of runtime objects. The non-perspective cameras can employ telecentric lenses.

The invention discloses a same-axis-center-distance equal-optical-flow catadioptric camera distance measurement system and a distance measurement method thereof. A center symmetry axis of a rotating body mirror plane and the optical axis of a perspective camera are collinear and have a fixed distance; a measured object is placed below the rotating body mirror plane, incident light of a measured object space point is reflected through the mirror plane and then imaged to the perspective camera, and the rotating body mirror plane has a mirror plane contour with an equal-optical-flow characteristic. The method comprises the steps: firstly building a simulation environment, and setting system parameters to obtained a relational expression between the axis center distance and the optical flow value; then actually measuring the distance, and after the camera acquires an image, calculating the optical flow value of the measured object space point at an imaged position on a camera imaging plane; and calculating the axis center distance from the measured object space point to the camera optical axis by using the relational expression, and thus achieving the distance measurement. With utilization of the equal-optical-flow characteristic of the rotating body mirror plane, the corresponding relationship is formed among the measured object space point, the camera optical axis and the optical flow, and thus the distance of a scene can be directly measured; and the system and the method can be used for unmanned aerial vehicle navigation and collision avoidance, and detect the height to the ground and the distance to obstacles.