81 results about "Cross Calibration" patented technology

The invention relates to a cross radiation calibration method based on the optimization algorithm of a hyper-spectral sensor; the cross radiation calibration method comprises the following steps of: (1) selecting an image to be calibrated; (2) selecting a reference image; (3) cutting out a region covered jointly by the two images, and selecting a uniform ground object to be used as a cross calibration interesting region; (4) working out the entrance pupil radiant brightness of the two sensors in each waveband and a gas absorbing characteristic curve, and removing gas absorption characteristics; (5) screening out the optimal wave band and the optimal interpolation scheme; (6) carrying out the cross radiation calibration on the optimal wave band of the hyper-spectral sensor; (7) interpolating the radiant brightness of the calibrated hyper-spectral waveband, reconstructing a hyper-spectral curve, loading the gas absorption characteristics to serve as the radiant brightness of the reference sensor; and (8) realizing the cross radiation calibration on the hyper-spectral sensor by using a multispectral sensor. The cross radiation calibration method can realize the in-orbit cross radiation calibration of a space-borne imaging spectrometer and has business popularization prospect.

A multiple modality imaging system (10) includes a MR scanner (12) which defines an MR imaging region (18), a nuclear imaging scanner (26) which defines a nuclear imaging region (34), an CT scanner (36) which defines an CT imaging region (42). Each scanner (12, 26, 36) having a longitudinal axis along which a common patient support (46) moves linearly through the MR, nuclear, and CT imaging regions (18, 34, 42). A marker (130, 140, 150), for use with the system (10), includes a radio-isotope marker (132) which is imageable by the nuclear imaging scanner (26) and the CT scanner (36) surrounded by a flexible silicone MR marker (134) which is imageable by the MR scanner (12) and the CT scanner (36). A calibration phantom(162), for use with the image scanner (10), includes a plurality of the markers (130, 140, 150) supported by a common frame having a known and predictable geometry.

The invention provides a cross radiation calibration method and system for a large observation angle sensor. The method comprises steps that a to-be-calibrated image and a reference image are registered, random sampling of each set of corresponding wave bands of the to-be-calibrated image and the reference image is respectively carried out to acquire corresponding calibration points; for each wave band, cross calibration for each pair of calibration points is carried out respectively, a BRDF adjusting coefficient is established as a ratio of a surface bidirectional reflection distribution function of the to-be-calibrated image and a surface bidirectional reflection distribution function of the reference image, and processing is carried out in an iteration mode; for each wave band, points with average mean values greater than a preset threshold are deleted from the cross calibration result, averaging is carried out, and a final radiation calibration coefficient is acquired. The method is advantaged in that BRDF values of the to-be-calibrated image and the reference image can be respectively calculated without a complex model, calculation is simple and stable, strong operationality is realized, and an error caused by introducing auxiliary data for BRDF calculation and influence of abnormal calibration points on the result can be further avoided.

The invention discloses a method for measuring the six-freedom-degree displacement and attitude of a model. A cross calibration rack is used for simulating a model and a wind tunnel coordinate system is established by using an absolute measuring arm; on the basis of measurement of coordinate values of a first circular hole, a second circular hole, a third circular hole and a fourth circular hole in the cross calibration rack under the wind tunnel coordinate system, a vector L1 of an axis of a first rod piece and a vector L2 of an axis of a second rod piece are calculated and an included angel between the vector L1 and a horizontal plane, an included angle between vector L1 and a vertical surface, and an included angle between the vector L2 and the horizontal plane are calculated; a pitching angle, a yaw angle and a rolling angle of the cross calibration rack are calculated and thus a pitching angle, a yaw angle, and a rolling angle of the model are calculated; and a mass center coordinate of the model under the wind tunnel coordinate system is calculated by using a coordinate value of a calibration hole in the wind tunnel coordinate system. Therefore, the integrated measuring problem of the displacement and attitude of the wind tunnel testing model can be solved; and measurement on the six-freedom-degree displacement and attitude of the model is realized. The measuring precision is high and the calculation speed is fast.

The invention discloses a relay zero-cross detection method and device and a relay zero-cross calibration method and device. The relay zero-cross detection method comprises the following steps: when a relay is turned on, monitoring the voltage phase of a controlled end of the relay; obtaining the time interval of adjacent two times of zero-cross of the voltage phase; and sending the time interval to the zero-cross calibration side of the relay. The relay is detected by setting the independent zero-cross detection device, and is free of requirement for product circuit; and meanwhile, the relay does not need to be screened again, so that the research and development time of the product can be effectively reduced, and the production cost of the product is reduced.

The invention discloses a data collection system based on a plurality of data routes and the cross-calibration and a data collection method adopted the system. The data collection system of the invention comprises a measuring channel, at least two measuring routes connected with the measuring channel and a measured data control unit connected with each measuring route. The measuring channel can be used for receiving input signals. Each measuring route comprises an analog-to-digital converter and an amplifier, the magnification factor of which is different from that of other routes. Each measuring route has a different measuring range. The measured data control unit comprises an input buffer, an output buffer, a cross-calibration computing module consisting of a digital logic circuit and a digital signal processor. The invention has the advantages that the invention can automatically adjust the best measurement range, and the measuring results are more accurate.

The invention relates to a geometric cross-calibration method and system for spaceborne SAR images. The method comprises the steps of step 1), establishing an atmospheric delay correction model of images to be calibrated; step 2) establishing a geometric calibration model of the images to be calibrated; step 3), selecting pairs of points with the same name from the images to be calibrated and reference images; step 4, according to imaging time of the images to be calibrated, using global atmospheric data provided by NCEP and ionospheric electron content distribution data provided by the European Orbit Determination Center (CODE), through the atmospheric delay correction model established in the step 1), calculating atmospheric delay correction values of the image to be calibrated; step 5),substituting the several pairs of points with the same name obtained in step 3) and the atmospheric delay correction values obtained in step 4) into the geometric calibration model established in step 2) to complete geometric calibration parameter solution. The method can achieve the normalization and short-period geometric calibration of a SAR satellite, do not need to arrange targets in advanceon the ground, and greatly save manpower and financial cost.

The invention discloses a water color satellite atmospheric layer top radiation product quality evaluation and cross calibration method. The method comprises the following steps: establishing a multi-source satellite quasi-synchronization effective pixel selection constraint condition; finding that radiation signal abnormity caused by the natural process has high interstellar correlation; designing a multi-source satellite radiation product error analytical equation; combining a dynamic cross radiation calibration mechanism; and determining the influence of the radiation product quality on the water color product. According to the scheme, constraint conditions of quasi-synchronous observation are specified for the first time, an analytic equation of multi-source satellite radiation product errors is determined, dynamic evaluation and cross calibration of the water radiation product quality are achieved, the defect that a traditional method is seriously influenced by abnormal signals caused by the natural process is overcome, and the water radiation product quality and the automatic service level are improved; and moreover, the method is easy to implement, can be used for dynamically monitoring and improving the quality of water radiation products, and has wider practical application value and economic value.

A method of electronic portal imaging (EPID) for radiation dosimetric measurement and quality assurance (QA) in radiation therapy is provided that includes imaging a calibration photon beam and a treatment beam using an EPID imager disposed between a plastic water build-up phantom and a plastic water back-scatter phantom that is thicker than the plastic water build-up phantom, correcting the EPID images using an off-axis correction map that takes into account a horn-shape of a photon fluence profile, deconvolving the corrected EPID images using a Monte Carlo simulated EPID response kernel, the deconvolved corrected EPID images provide a primary photon fluence map, reconstructing a relative dose map using the primary photon fluence map convolving with a Monte Carlo simulated pencil-beam dose distribution kernel, and generating an absolute dose map using cross calibration to a 10x10 cm2 square field that is compared with a planned dose distribution for QA analysis.

The invention belongs to the technical field of remote sensing, and discloses a sea ice density acquisition method based on a space-time system point value, which comprises the following steps: acquiring original strip data and preprocessing to obtain day-scale brightness temperature data; performing cross calibration on the daily scale brightness temperature data to obtain calibrated daily scalebrightness temperature data; calculating and obtaining initial sea ice density by utilizing an ASI algorithm; giving a primary sea ice density condition, a spatial position condition and a time condition, selecting sample points for calculating a daily sea ice system point value and a seawater system point value, and taking an average value of the sample points as a daily new system point value; calculating and obtaining secondary sea ice density by utilizing an ASI algorithm on the basis of the new daily coefficient value; and removing false ice by using a weather filter and a maximum sea icerange mask to obtain daily-scale sea ice density. According to the invention, the problem of low precision of sea ice density obtained in the prior art is solved. The precision of the sea ice densityobtained by the method is higher than that of sea ice density obtained based on a fixed system point value.

The invention discloses a switch-on type and continuous inflow type dual-purpose density current test device and method. The device comprises a water storage tank, a vacuum pump, a sediment suspensioninstrument, a flowmeter, a flow guide pipe, a drain pipe, a valve switch, a water tank, pulleys, a guide rod and a guide rail. The device also comprises scale lines and a cross calibration line. Thetest method of the switch-on type and continuous inflow type dual-purpose density current test device comprises the following steps: the test preparation process, the test process, the instrument arrangement process and the data processing and analysis process. The device has the advantages of novel design, simple structure, good integrity, wide applicability to working conditions and high test accuracy; the device can simulate the switch-on type and continuous inflow type density current flow process under the influence of different density current concentration, bed roughness and topographicabrupt change and the continuous inflow type density current movement process under different degrees of gate opening; and the test process is easy to operate, the test efficiency is high and the test design is flexible.

The invention discloses an agricultural and forestry crop identification method based on medium-high resolution time sequence remote sensing data. The method comprises the steps of 1) carrying out thecross calibration on remote sensing images observed by multiple medium-high resolution remote sensors in the same region at different times; 2) for remote sensing images with different spatial resolutions, forming a remote sensing time sequence data set with consistent spatial resolutions and short time intervals on the basis of cross calibration; 3) segmenting the agriculture and forestry land parcels in the remote sensing image by using an image segmentation method to obtain the boundary of each land parcel; 4) analyzing the remote sensing time sequence data set by taking the land parcels as units, and counting the average value and variance of the spectral band reflectivity, the normalized vegetation index and the leaf area index of the land parcels in each period; sorting the statistical characteristics according to time to form a plurality of characteristic curves of the plot; and 5) matching the plurality of characteristic curves of the agriculture and forestry land parcels withthe phenological characteristic library to obtain the crop types of the land parcels.

The invention discloses a simulation method for remote sensing data under arbitrary spectral response characteristic, and belongs to the technical field of earth observation. In the method, the input hyperspectral data is subjected to iteration decorrelation, and hyperspectral data with improved spectral resolution is acquired; and the hyperspectral data with the improved spectral resolution is sampled according to the spectral response characteristic to be simulated, and hyperspectral or multispectral data under the spectral response characteristic to be simulated is acquired. The simulation method can be used for simulating the hyperspectral or multispectral data with arbitrary central wavelength position, arbitrary spectral resolution or arbitrary shape spectral response function by the existing hyperspectral data, and has higher accuracy of simulating data than the conventional spectral interpolation method and wave-band synthesis method so as to contribute to improving radiometric cross-calibration accuracy and data comparison and verification accuracy of a hyperspectral remote sensor.

Improved cross-calibration between magnetic resonance imaging (MRI) coordinates and optical tracking coordinates is provided. Initial calibration is performed with a calibration tool that includes wireless active markers that can be tracked using the MRI scanner, and an optical marker that can be tracked using the optical tracking system. Data from one or more poses of this tool are used to provide an initial cross-calibration. In use, this initial calibration is corrected to account for differences between actual camera position and the reference location. Here the reference location is the camera location at which the initial calibration was performed.

The invention relates to an optical remote sensing satellite radiation cross calibration method based on a stable radiation source, and the method comprises the following steps: a, carrying out the calibration of an optical remote sensing satellite through a satellite-borne black body, and obtaining a calibration coefficient; b, calculating a radiation value of the stable radiation source according to the calibration coefficient; c, repeating the step (a) and the step (b) to obtain a series of calibration coefficients and radiation values; and d, selectively performing radiation correction according to the decay condition of the radiation measurement performance of the optical remote sensing satellite. The method can achieve the stable correction of the in-orbit absolute radiation reference of the optical remote sensing satellite, and provides support for the quantitative processing and application of remote sensing data.

An online monitoring system for industrial processes, such as nuclear power processes, including a data acquisition unit configured to sample output signals simultaneously from a plurality of process sensors, and a computing unit configured to record sampled output signals from the data acquisition unit and to cross-correlate the output signals from two or more of the process sensors to diagnose operation of the industrial process, identify loose parts and/or degradation of industrial plant equipment, enable virtual sensing, calculate sensor response time using the noise analysis technique, and to verify sensor calibration using the cross calibration method and/or empirical and/or physical modeling.

The invention discloses an electric cooker and a zero-crossing calibration circuit and a zero-crossing calibration method thereof. The electric cooker comprises a resonance circuit, a power switch tube and a drive module. The resonance circuit is connected with a collector electrode of the power switch tube, and has a first node. The zero-crossing calibration circuit comprises a zero-crossing detection unit, a resonance voltage detection unit and a control unit, wherein the zero-crossing detection unit is used for detecting a zero-crossing point of an input AC power supply to output a zero-crossing signal; the resonance voltage detection unit is connected with the first node to detect resonance voltage of the first node; the zero-crossing detection end of the control unit is connected withthe zero-crossing detection unit; the AD sampling end of the control unit is connected with the resonance voltage detection unit; and the control unit judges that zero-cross detection is wrong, and carries out processing on the zero-crossing signal in the process where the zero-crossing detection end detects that the zero-passing signal changes from a falling edge to a rising edge, and when the AD sampling end samples the resonance voltage of the first node and the resonance voltage of the first node is larger than a preset voltage.

The invention provides a multi-dimensional cross calibration method in the test and measurement. The method comprises the following steps of determining a measured physical quantity and a real directly-measured parameter; determining all factors influencing the measured physical quantity; determining an intersection of all the factors and a measuring point of each factor containing the measured physical quantity; first measuring a direct parameter value at the intersection, and then measuring a direct parameter value of each measuring point of each factor and a value at the intersection of other factors in measurement; determining the relation between the measured physical quantity and the direct parameter as well as between the direct parameters; normalizing error values of all the factors on the intersection; calculating a value of the measured physical quantity, and completing the calibration and measurement. The method is not subjected to the limit of the dimensions, the relation between the direct parameter and each factor can be conveniently approximated through a polyline method, and the method is easily realized on the engineering; by adopting the normalization concept, only the points on the intersection are measured, so that the measurement data are greatly reduced; by adopting the polyline method, the measurement precision is high.

The invention provides a cross calibration method and device for the significant wave height of a wave buoy, electronic equipment and a storage medium. The method comprises the steps of acquiring historical remote sensing wave significant wave height data and historical wave significant wave height data observed by buoys of different specifications; performing space-time matching, numerical discrete averaging and matching regression on the historical remote sensing wave significant wave height data and historical wave significant wave height data observed by buoys of different specifications,and establishing a buoy significant wave height cross calibration equation; acquiring wave observation data of a to-be-calibrated wave buoy, the wave observation data being significant wave height data of waves; and correcting the wave significant wave height data through the buoy significant wave height cross calibration equation to obtain corrected buoy wave significant wave height data. By implementing the embodiment of the invention, cross calibration can be performed on significant wave height observation of buoys of different specifications, the consistency of significant wave heights ofwaves in observation data of a wave buoy is improved, and the application reliability and application value of wave observation by a wave buoy are effectively improved.

The invention discloses a laser comprehensive reference system for underwater detection and a distance measurement and calibration method. The system has the main functions of laser ranging and high-definition zoom camera laser calibration, and is mainly composed of a fixed laser, a rotary laser, a fixed platform, a support, a laser frame, a central processing unit, a three-dimensional motion platform, a zoom high-definition camera, a two-end laser rotating device, a target object and the like. In the ranging process, a straight line extraction module is used to obtain a rough shape of a laser line, and a straight line fitting module fits a straight line; a target object shape judgment module judges the shape of a target object; a target plane inclination judgment module judges whether the target plane is inclined or not; a distance measuring module obtains a distance between the target object and the system, meanwhile, different results are obtained according to different target objects, online calibration of a high-definition zoom camera is achieved through an online cross calibration method, internal and external parameters of the camera are obtained through a calibration module in the calibration process, and a distortionless image is obtained through calibration of an image obtained according to the parameters.