95 results about "Laser altimetry" patented technology

A method is presented for rapidly making and delivering directly to a consumer a full upper and/or lower denture on the basis of contemporaneous digital image information laser scanned from the person's oral cavity after all respective upper and/or lower teeth have been removed, the delivery of the denture occurring substantially contemporaneously with the creation of the contemporaneous digital image information and optionally including and based on archived digital image information laser scanned from the person's oral cavity before all respective upper and/or lower teeth have been removed and digitally stored. According to which this contemporaneous digital image information and archival digital image information of the oral cavity is converted, by means of what is called the rapid prototyping technique and thus with a processing step (20) and a combination of an optional laser scanning step (18) solely for archiving the oral cavity when upper and/or lower teeth are present and a repetition of the laser scanning step (18) at a subsequent time when upper and/or lower teeth have been removed, a pre-selected block of plastic is used in a processing step (26) at a remote rapid modeling facility for receiving and processing digital information to form the block of plastic or like material into a denture of which at least a part is formed to substantially perfectly fit in juxtaposed relationship to the corresponding gums of the consumer. At least, pre-selected outer or non-juxtaposing is selected for manufacture of the denture using an arbitrary archived digital image not derived from the consumer's oral cavity image but selected by the consumer for its style, cosmetic characteristics, for example, color of teeth, size and variety of teeth, and/or perceived suitability.

A laser-based altimeter for use on-board an aircraft comprises: a first housing including a hollow cavity and an exit aperture, and a second housing including a hollow cavity and an entrance aperture. A laser source and a plurality of first optical elements are fixedly supported in a compact configuration within the hollow cavity of the first housing. The plurality of first optical elements directs laser beams generated by the laser source from a first optical path to a second optical path which exits the first housing through the exit aperture. At least one second optical element is configured within the hollow cavity of the second housing to form a telescope with a predetermined field of view. The telescope receives at the entrance aperture reflections of the pulsed laser beams from objects within the field of view thereof and focuses the received reflections substantially to a focal point. A light detector is included for receiving and converting the focused reflections into electrical signals representative thereof. The first and second housings are fixedly secured in alignment with respect to each other to permit the second optical path of the pulsed laser beams to be adjusted within the field of view of the telescope. A mirror apparatus is the only first optical element of the plurality that is fixedly adjustable for directing the second optical path within the field of view of the telescope, the mirror apparatus being lockable in place after final adjustment. The first and second housings may be part of a common housing.

The invention discloses a satellite-based laser on-orbit orientation calibration method based on pyramidal searching terrain matching. The satellite-based laser on-orbit orientation calibration method comprises the following steps: step 1, extracting laser data and terrain data; step 2, constructing a satellite-based laser height indicator geometric calibration model based on the extracted laser data; step 3, determining a calibrated laser orientation angle by utilizing a pyramidal searching method based on the terrain data extracted in the step 1 and the satellite-based laser height indicator geometric calibration model constructed in the step 2. The satellite-based laser on-orbit orientation calibration method disclosed by the invention can be widely applied to domestic satellite-based laser on-orbit geometric calibration; the method has small implementation difficulty and does not depend on waveform data; the satellite-based laser on-orbit orientation calibration method has important significance on capturing in primary ground calibration of a ground detector and high-precision geometric rough calibration of satellite-based laser.

The invention provides a satellite laser altimeter directional angle system error calibration method based on a directional angle residual error. On the basis of ground detecting a laser spot, the directional angle residual error of a satellite laser altimeter is established according to the position of a located laser spot; based on the directional angle residual error, the relation between a directional angle system error and the directional angle residual error is established; and the directional angle residual error is formed by using the directional angle measured by a satellite system and a laser directional angle calculated by ground spot detection, and the directional angle residual error is used to achieve on-orbit calibration of a satellite laser altimeter directional angle system error. The invention can well calibrate the directional angle system error.

The invention provides a satellite-borne laser altimeter on-orbit calibration method and system. On the basis of an existing on-orbit calibration method, according to a known earth surface prior model, a distance measuring model of a satellite-borne laser altimeter is built; based on the distance measuring model, a relation between a system error and a distance measuring residual error is established; and an actual measurement distance value and the distance measuring model are utilized to calculate a distance value and generate a distance measuring residual error, and the distance measuring residual error is utilized to realize on-orbit calibration of an assembling error and a distance measuring error in system errors of a height measurement system. The technical scheme of the satellite-borne laser altimeter on-orbit calibration method can well calibrate system errors, thereby avoiding attitude maneuver.

The invention relates to an ocean surface wind and wave feature retrieval method based on an echo of a spaceborne laser height indicator. The method comprises the steps of preprocessing and extracting the features of echo waveform of the spaceborne laser height indicator, and then establishing a mathematic relation between the extracted echo waveform and the ocean surface wind field and wave field, thus calculating the slope and the height of the ocean surface wave and the wind speed of ocean surface through a retrieval way according to the echo parameters. On the basis that laser beam has the characteristics that the divergence angle is far less than that of a microwave beam, the method for inverting the ocean surface wind speed under the echo pulse width by adopting the spaceborne laser height indicator has foot positioning precision and space resolution ratio higher than those of currently commonly used method for inverting the wind speed through the scattering section of a radar of a microwave radar height indicator.

The invention relates to a laser ceilometer dynamic threshold selecting method based on pulse echo forms, and belongs to the field of laser remote sensing. The laser ceilometer dynamic threshold selecting method based on the pulse echo forms solves the problems that in an existing threshold selecting method, only extreme point positions or fifty-percent peak point positions or dual-threshold positions of pulse echoes are adopted to confirm transition time of laser pulses, the selected thresholds can be only suitable for specific measurement conditions or plane targets of small slopes. According to the laser ceilometer dynamic threshold selecting method based on the pulse echo forms, a mathematic model of the laser ceilometer pulse echo forms, noise standard deviation and threshold rising edge moment variance is regarded as a theoretical basis, the range error minimization of a laser ceilometer serves as a basis, and the optimization selection of the threshold coefficient of the laser ceilometer is achieved through a parameter iterative search method. The influences of noise and pulse widening introduced by gap title effects of the plane targets are fully considered in the threshold value selection method, range errors caused by threshold setting can be reduced, and the satellite-borne laser ceilometer can complete high-precision laser ranging of the plane targets of different slopes under different measurement conditions.

The invention relates to an intelligent data acquisition method and a system used for space-based laser altimetry. The intelligent data acquisition method of the invention can control and conduct abnormal handling on the data acquisition process, complete accurate and synchronous dual-channel high-speed data acquisition and realize real-time high-capacity intelligent data storage. The intelligent data acquisition system of the invention mainly comprises a signal conditioning unit, a signal transfer switch, an analog-to-digital conversion unit, a data cache unit and a data and control unit; wherein, the dual channels respectively receive emission waves and echoes of a laser altimeter. The invention is characterized by compact system structure, small volume, stable and reliable circuit, large detected dynamic range, little analog-to-digital conversion error, high accuracy and robustness, capability of stably working for a long time without a break, capability of acquiring, transferring and storing all the useful data in real time, capability of adding the radar detection function to the space-based laser altimeter and capability of obtaining surface elevation distribution within the range of light spots and reflectivity.

A method of elevation control points extraction assisted by satellite laser altimeter data, which is characterized in that take the waveforms received by satellite and the waveforms simulated from digital surface model (DSM) of image scene reconstruction as input data, and includes two times of waveform matching and combined process of multi-source remote sensing data. The elevation control points could be extracted without the influence of terrain fluctuation or urban buildings for the terrain information of laser spot area has been taken into account. The first time is realized by matching two groups of waveforms from the received and the simulated, and the spatial registrations between locations of laser spots and DSM are realized. The second time is realized by matching two single waveforms from the received and the simulated, and local system errors in DSM of laser spot area could be extracted. With the registration results and local system errors, many applications including extraction of elevation control points could be easily developed. The invention mainly includes the following steps: (1) Preliminary refinement of orientation parameters of high-resolution stereo or InSAR images by free net adjustment; (2) DSM reconstruction with high-resolution stereo images or InSAR data; (3) dividing the received laser altimetry data into groups; (4) Waveform extraction of the receiving group; (5) observation design for simulation waveform group; (6) simulation waveform acquisition through observation of DSM; (7) matching the received group waveforms with the simulated group waveforms; (8) plane position registration between laser spot and DSM; (9) matching each pair of waveforms in group between the received and the simulated respectively; (10) extraction of DSM elevation system errors on each laser spot area; (11) extraction of image elevation control points; (12) refinement of DSM elevation, calibration of satellite laser altimeter sensor, combined processing with laser altimetry and image remote sensing. The invention mainly solves two difficulties. One difficulty is finding footprints, or say laser spot areas, of satellite laser altimeters on stereoscopic images, InSAR images and the DSM they generate. Another difficulty is the accurate elevation extraction of laser spot areas with uneven terrain. The invention can realize the spatial registration between laser spot and DSM or remote sensing in different terrain and establish spatial connection between laser altimetry data and stereo images or InSAR data. In different terrain conditions, by the invention, the satellite laser altimetry data can be used for high-precision elevation control of 3D reconstruction/positioning of stereo images or InSAR data.

The invention relates to an elevation calibration method and device for digital elevation model data. The method comprises the following steps: unifying height datum of ice cloud and ground level geoscientific laser altimetry data and height datum of digital elevation model data;extracting a geoscientific laser altimetry data elevation value and a digital elevation model elevation value of the same point location; establishing an elevation calibration model using the geoscientific laser altimetry data elevation value and the digital elevation model elevation value of the same point location; and calibrating the digital elevation model data using the elevation calibration model. According to the technical scheme, the elevation calibration model is established based on the ice cloud and ground level satellite geoscientific laser altimetry data, elevation calibration is performed on the digital elevation model of space shuttle radar mapping plan through the elevation calibration model so that the elevation value precision of the digital elevation model is greatly improved, the calibrated digital elevation model becomes reliable fundamental geographic information data and provides reference for developing various scientific research and engineering applications.

The invention comprises a satellite-borne laser height measuring instrument footprint positioning method based on a passive target, solving the problem that echo signals of a flat terrain area are high in similarity by arranging an angle reflector array in the flat terrain area to mark the target echo to be measured in the flat terrain area, so that the high-precision positioning of the height measurement instrument footprint can be realized in a manner of waveform analysis in the flat terrain area, and the authenticity verification of the footprint position which is resolved by the height measurement instrument is finally realized. The method comprises angle reflector caliber design, angle reflector layout scheme, CCR energy contour line circle extraction, and footprint center extractionbased on a steepest descent method. The system includes a CCR caliber calculation module, a CCR layout scheme module and a CCR-based footprint positioning module. According to the technical scheme, the positioning of the height measurement instrument footprint can be achieved through the waveform analysis mode in the flat terrain area.

The invention relates to a single-photon laser height measurement data denoising method and device based on density statistics. The method comprises the following steps: 1) obtaining single-photon laser altimetry data; 2) performing data preprocessing; 3) carrying out photon density calculation by using an ellipse search area whose direction and size change adaptively with the gradient; and 4) adaptively calculating segmented threshold separation signal photons and noise photons by adopting an OTSU method, and removing discrete noise points by adopting a K nearest neighbor distance. Compared with the prior art, the method is not influenced by non-uniform background noise photons, and is high in adaptability, the direction of the search ellipse can be changed adaptively along with the slope, the size can be changed, signal photons and noise photons of each segment are separated by using the segmentation threshold, and a small number of discrete noise points left after rough denoising are further removed; and the method is complete in signal extraction, high in denoising precision and high in efficiency.

The invention discloses a method for removing gross errors of a space-borne laser altimeter integrated with multi-source data. The method is as follows according to specific steps: (1) calculate the echo reflectivity, and then remove the laser echo data whose reflectivity is too low; (2) Identify the position of the cloud layer from the image of the footprint camera and remove the laser echo data reflected by the cloud layer; (3) With the support of auxiliary data, generate generalized elevation control points from the echo data of the altimeter; (4) Use the reference DEM data Auxiliary elimination of gross errors in the altimetry data; (5) Substituting the altimetry data into the stereoscopic image as elevation control points to assist in the block adjustment under weak intersection conditions, and continuously eliminating the point with the largest elevation difference until the adjustment The result converges. The elevation control point data can be obtained through this method, and the production precision of the global terrain data can be improved. Since the present invention combines multiple data to eliminate gross errors, the problem of low precision under a single reference source is avoided, and it has the characteristics of good robustness and high precision.

The invention discloses a waveform matching-based on-orbit pointing calibration method of spaceborne laser. The method includes the following steps: carrying out echo waveform simulation of a spaceborne laser altimeter on the basis of airborne lidar (Light Detection And Ranging) data; matching a real waveform according to an obtained simulation waveform, and determining foot point centroid coordinates of the spaceborne laser according to a method of matching the real waveform by the simulation waveform; and calibrating a pointing angle of the spaceborne laser according to a geometric calibration model of the spaceborne laser altimeter and the foot point centroid coordinates of the laser. According to the calibration method, the simulation waveform is adopted to match the real waveform, thus a foot point centroid position of the laser is quickly determined, and the purpose of on-orbit pointing calibration of the spaceborne laser altimeter is achieved. By using the calibration method, ground detectors are no longer relied on, only the existing airborne lidar data need to be used, and field operation cost can be greatly reduced.

The invention discloses a method of pre-determining footprint position of a satellite laser altimeter. In the method, a traditional optical camera imaging principle is applied and altitude measurement mechanism of the laser altimeter is fully considered. A footprint position determination result satisfies actual flight transit situation of a satellite well. The method is high in calculation precision, reduces unnecessary labor intensity and resource consumption as most as possible, and saves a large amount of test cost.

The invention discloses a full-link photon counting laser altimeter point cloud generation method. A full-link simulation model including ground light spot coordinate calculation, atmospheric refraction offset correction, target geometry and radiation characteristics, detector response and the like in the height measurement process of a satellite-borne laser altimeter is established, and high-precision single-photon point cloud is generated through simulation in combination with satellite platform parameters, laser altimeter system parameters, environmental parameters, target characteristic parameters and the like. The laser altimeter point cloud generation method can accurately adjust various system parameters and environmental parameters, and has the advantages of being rapid, easy to simulate various conditions and good in expansibility. ICESat-2 system parameters can be used as input to simulate and detect randomly generated terrain surfaces, and high-quality photon point clouds are generated.

The invention relates to an aerosol thickness and laser radar ranging delay automatic calibration method. The method is characterized in that correlation coefficient is established based on pixel values of aerosol content extracted from images and range error values of the sea surface, and transfer coefficient of the range errors represented by the dimensionless pixel values of an aerosol content distribution diagram, so that accurate correction of height measurement value of the land surface can be realized. The relation between image aerosol brightness values and atmosphere wet delay, that is, aerosol delay amount, is established automatically without ground actually-measured data, thereby realizing accurate atmosphere wet term correction of any height measurement data, and playing an important correction role in correcting the height measurement data of a satellite-borne laser altimeter.

The invention discloses an arrangement method of a ground detector for spaceborne laser altimeter calibration. The method comprises the following steps that S1, a laser altimeter calibration area is selected; S2, a detector arrangement area is gradually reduced in the laser altimeter calibration area selected in the step S1, and finally the arrangement central point position of the ground detector is determined; and S3, the ground detector is arranged and adjusted at the arrangement central point position of the ground detector determined in the step S2. Implementation of each step is reasonably arranged so that the arrangement efficiency of the detector can be enhanced to a great extent, orderly performing of arrangement of the ground detector can be guaranteed and the working efficiency can be greatly enhanced.

The present invention discloses a laser ceilometer integrated test system and an integrated test method thereof, belonging to the technical field of lasers. The laser ceilometer integrated test systemand the integrated test method thereof achieve simulation of different surface features and simulation of a solar spectrum required by performance test of a laser-measured height subsystem in a mapping camera, and are applied to calibration of index parameters of the laser-measured height subsystem, wherein the index parameters comprise delay time constant of a whole machine, distance measurementprecision, a distance measurement range, distance measurement resolution, detection sensitivity, the maximum ranging, etc. The laser ceilometer integrated test system is high in integration, convenient and rapid in control, and can improve the reliability and the stability of the laser ceilometer integrated test system on the basis of achieving the functions mentioned above.

The invention relates to a determination method for satellite laser ceilometer pin point geometry positioning errors and belongs to the field of laser remote sensing. The problems that an existing pin point geometry positioning error analysis method neglects position and the angle placement errors between a laser measuring system and a carrying platform sensor, only provides partial instant geometry positioning error molds of laser pin points on the premise that height fluctuations of a measured target are not considered and does not analyze extreme values of laser pin point geometry positioning errors are solved. On the basis of the satellite laser ceilometer pin point geometry laser pin point geometry positioning process and error communication theory, the method for comprehensively determining the satellite laser ceilometer laser pin point geometry positioning errors is provided by comprehensively considering the influence on various error sources and plane target fluctuations; the analysis method with the combination of the instant geometry positioning error and the extreme geometry positioning error can achieve comprehensive analysis and evaluation of performance indexes obtained before and after emission of a satellite laser ceilometer.

The invention discloses a two-linear array space mapping camera and laser altimeter integral device, and belongs to the field of space remote sensing. The device assists in solving the problems of large integral outer envelope size and low mapping precision of split design of a laser altimeter and a camera. The device comprises a housing, a front base plate and a back base plate respectively fixed on two ends of the housing, an oblique camera with a main body arranged in the housing, a straight camera arranged in the housing, a star sensor fixed on the outer surface of the housing and close to the edge of the back base plate, and a laser altimeter with a main body arranged in the housing. Main three lenses of the oblique camera are fixedly distributed on the right side of the back base plate, and an oblique incident hole is fixed on the outer surface of the housing and closes to the edge of the front base plate. Main three lenses of the straight camera are fixedly distributed on the left side of the back base plate, and a straight incident hole is fixed on a left-lower end of the front base plate. The part of the laser altimeter outside the housing is fixed on the right-lower end of the front base plate through screws. The integral device provided by the invention has the advantages of small outer envelope size and high mapping precision.

The invention provides a train coal density measuring system which comprises a laser altimeter, a pressure sensor, a train number recognizer and an upper computer. The laser altimeter, the pressure sensor and the train number recognizer are connected with the upper computer, the laser altimeter is used for detecting the height of coal in a train wagon and sending detected data to the upper computer, the pressure sensor is used for detecting the total weight of the train wagon after the coal is loaded and sending detected data to the upper computer, and the train number recognizer is used for recognizing the specification of the train wagon and sending recognized data to the upper computer. The train coal density measuring system has the advantages that the height of the coal in a train can be measured in real time and is directly reflected, human factor interference can be significantly reduced, and adulteration and falsification can be effectively evaded in time.

The invention provides a small mobile eddy correlation turbulence water and heat fluxes observation system and method. The small mobile eddy correlation turbulence water and heat fluxes observation system is carriedabove a fixed-wing drone andcomprises an onboard 5-hole turbulence probing head, a thermocouple probing pin, a quick response hygrometer, a temperature and humidity sensor, a net radiometer, a photosynthetically active radiometer, an infrared thermometer, a laser altimeter, a GPS-assisted inertial navigation system, a wireless communication module, an input device, an analog/digitalsignal converter, and a data acquisition control computer. The small mobile eddy correlation turbulence water and heat fluxes observation system and method have the advantages that the small mobile eddy correlation turbulence water and heat fluxes observation system is carriedonthe fixed-wing drone and used for direct observation of earth surface turbulence water and heat fluxes at a regional scale, and the advantages of having low observation cost and good portability and flexibility are obtained. The range of the earth surface representable by flux calculation result ofeach turbulence fluxobservation windowscancommonly cover several square kilometers, and the research and application of moderate and coarse resolution remote sensing images and land surface process model grid scale can be sufficiently satisfied.

The invention discloses a cesium light pump magnetic measuring method based on a fixed-wing unmanned aerial vehicle. The method includes: presetting a testing qualification standard, conducting performance testing on the unmanned aerial vehicle, and if testing is qualified, establishing signal connection between a ground measurement and control station and the unmanned aerial vehicle; if the testing is unqualified, conducting the performance testing of the unmanned aerial vehicle again; after the unmanned aerial vehicle reaches measurement height, calculating magnetic compensation coefficient;after magnetic compensation is completed, respectively transmitting magnetic measuring data measured by a cesium light pump magnetometer and navigation data measured by a laser altimeter, a GPS and an IMU to a data collection box through a serial port; after the data collection box receives corresponding magnetic measuring data and navigation data, transmitting the same to a field data preprocessing system for data processing; performing aeromagnetic interpretation on processed data. By the method, measuring accuracy, working efficiency and flying safety are improved, and weight, size and cost of the unmanned aerial vehicle are reduced.