The accuracy of Digital Surface Models(DSMs)generated using stereo matching methods varies due to the varying acquisition conditions and configuration parameters of stereo images.It has been a good practice to fuse th...The accuracy of Digital Surface Models(DSMs)generated using stereo matching methods varies due to the varying acquisition conditions and configuration parameters of stereo images.It has been a good practice to fuse these DSMs generated from various stereo pairs to achieve enhanced,in which multiple DSMs are combined through computational approaches into a single,more accurate,and complete DSM.However,accurately characterizing detailed objects and their boundaries still present a challenge since most boundary-ware fusion methods still struggle to achieve sharpened depth discontinuities due to the averaging effects of different DSMs.Therefore,we propose a simple and efficient adaptive image-guided DSM fusion method that applies k-means clustering on small patches of the orthophoto to guide the pixel-level fusion adapted to the most consistent and relevant elevation points.The experiment results show that our proposed method has outperformed comparing methods in accuracy and the ability to preserve sharpened depth edges.展开更多
It is usually a time-consuming process to real-time set up 3D digital surface model(DSM) of an object with complex surface.On the basis of the architectural survey project of"Chilin Nunnery Reconstruction",t...It is usually a time-consuming process to real-time set up 3D digital surface model(DSM) of an object with complex surface.On the basis of the architectural survey project of"Chilin Nunnery Reconstruction",this paper investigates an easy and feasible way,that is,on project site,applying digital close range photogrammetry and CAD technique to establish the DSM for simulating ancient architectures with complex surface.The method has been proved very effective in practice.展开更多
Global demand for soil data and information for maintaining and improving agricultural productivity and environmental health is soaring.The accurate and rapid digital maps of soil characteristics are of key importance...Global demand for soil data and information for maintaining and improving agricultural productivity and environmental health is soaring.The accurate and rapid digital maps of soil characteristics are of key importance for evaluation of soil fertility,precision management of crop inputs,estimation of carbon stocks,and modeling ecological responses as well as environmental threats.展开更多
A new digital transmitter based on delta sigma modulator( DSM) with bus-splitting is presented in this paper. The second order low pass error-feedback delta sigma modulator( EF-DSM) is focused. The signal to noise rat...A new digital transmitter based on delta sigma modulator( DSM) with bus-splitting is presented in this paper. The second order low pass error-feedback delta sigma modulator( EF-DSM) is focused. The signal to noise ratio( SNR) of the EF-DSM is derived for different bus-splitting bits.Following the EF-DSM,a multi-bit digital up mixer is used for carrier frequency transform. In order to validate the theory of bus-splitting,two types of transmitters are implemented on FPGA for comparison,in which one is with non-bus-splitting and the other is with bus-splitting. The FPGA implemented transmitter with bus-splitting promotes the maximum operation speed by 39%,and reduces hardware consumptions more than 16%. Both single tone and orthogonal frequency division multiplexing( OFDM) signal source are used to evaluate the proposed transmitter.展开更多
Time-interleaved structure can promote the equivalent processing speed of a digital signal processing system. An improved time-interleaved error feedback delta sigma modulator( TI-EF-DSM)for digital transmitter applic...Time-interleaved structure can promote the equivalent processing speed of a digital signal processing system. An improved time-interleaved error feedback delta sigma modulator( TI-EF-DSM)for digital transmitter application is presented in this paper. Two TI-EF-DSMs are compared,one is a conventional directly implemented and the other is the improved. The processing speed of the proposed two-channel improved time-interleaved error feedback delta sigma modulator( ITI-EF-DSM) is higher than the conventional directly implemented TI-EF-DSM for shortened critical path. A digital transmitter based on the ITI-EF-DSM is implemented on field progrmmable gate array( FPGA). The long term evolution( LTE) signals with different bandwidths of 5 MHz,10 MHz and 20 MHz are used as the signal source to evaluate the transmitter. The achieved SNR is 41 dB for the 20 MHz LTE signal with the processing clock of only 184 MHz.展开更多
基金John Hopkins University Applied Physics Lab to support the Imagery of the 2019 DFC datasets
文摘The accuracy of Digital Surface Models(DSMs)generated using stereo matching methods varies due to the varying acquisition conditions and configuration parameters of stereo images.It has been a good practice to fuse these DSMs generated from various stereo pairs to achieve enhanced,in which multiple DSMs are combined through computational approaches into a single,more accurate,and complete DSM.However,accurately characterizing detailed objects and their boundaries still present a challenge since most boundary-ware fusion methods still struggle to achieve sharpened depth discontinuities due to the averaging effects of different DSMs.Therefore,we propose a simple and efficient adaptive image-guided DSM fusion method that applies k-means clustering on small patches of the orthophoto to guide the pixel-level fusion adapted to the most consistent and relevant elevation points.The experiment results show that our proposed method has outperformed comparing methods in accuracy and the ability to preserve sharpened depth edges.
文摘It is usually a time-consuming process to real-time set up 3D digital surface model(DSM) of an object with complex surface.On the basis of the architectural survey project of"Chilin Nunnery Reconstruction",this paper investigates an easy and feasible way,that is,on project site,applying digital close range photogrammetry and CAD technique to establish the DSM for simulating ancient architectures with complex surface.The method has been proved very effective in practice.
文摘Global demand for soil data and information for maintaining and improving agricultural productivity and environmental health is soaring.The accurate and rapid digital maps of soil characteristics are of key importance for evaluation of soil fertility,precision management of crop inputs,estimation of carbon stocks,and modeling ecological responses as well as environmental threats.
基金Supported by the National Natural Science Foundation of China(No.61674037)National Key Research and Development Program of China(No.2016YFC0800400)+1 种基金the Priority Academic Program Development of Jiangsu Higher Education Institutionsthe National Power Grid Corp Science and Technology Project(No.SGTYHT/16-JS-198)
文摘A new digital transmitter based on delta sigma modulator( DSM) with bus-splitting is presented in this paper. The second order low pass error-feedback delta sigma modulator( EF-DSM) is focused. The signal to noise ratio( SNR) of the EF-DSM is derived for different bus-splitting bits.Following the EF-DSM,a multi-bit digital up mixer is used for carrier frequency transform. In order to validate the theory of bus-splitting,two types of transmitters are implemented on FPGA for comparison,in which one is with non-bus-splitting and the other is with bus-splitting. The FPGA implemented transmitter with bus-splitting promotes the maximum operation speed by 39%,and reduces hardware consumptions more than 16%. Both single tone and orthogonal frequency division multiplexing( OFDM) signal source are used to evaluate the proposed transmitter.
基金Supported by the National Natural Science Foundation of China(No.61674037)the National Key Research and Development Program of China(No.2016YFC0800400)+2 种基金the Priority Academic Program Development of Jiangsu Higher Education Institutionsthe National Power Grid Corp Science and Technology Project(No.SGTYHT/16-JS-198)the State Grid Nanjing Power Supply Company Project(No.1701052)
文摘Time-interleaved structure can promote the equivalent processing speed of a digital signal processing system. An improved time-interleaved error feedback delta sigma modulator( TI-EF-DSM)for digital transmitter application is presented in this paper. Two TI-EF-DSMs are compared,one is a conventional directly implemented and the other is the improved. The processing speed of the proposed two-channel improved time-interleaved error feedback delta sigma modulator( ITI-EF-DSM) is higher than the conventional directly implemented TI-EF-DSM for shortened critical path. A digital transmitter based on the ITI-EF-DSM is implemented on field progrmmable gate array( FPGA). The long term evolution( LTE) signals with different bandwidths of 5 MHz,10 MHz and 20 MHz are used as the signal source to evaluate the transmitter. The achieved SNR is 41 dB for the 20 MHz LTE signal with the processing clock of only 184 MHz.
