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摘要:
现有无人机(UAV)影像三维重建方法在功耗、时效等方面无法满足移动终端对低功耗、高时效的需求。为此,在有限资源FPGA平台下,结合指令优化策略和软硬件协同优化方法,提出一种基于FPGA高吞吐量硬件优化架构的无人机航拍影像快速低功耗高精度三维重建方法。首先,构建多尺度深度图融合算法架构,增强传统FPGA相位相关算法对不可信区域的鲁棒性,如低纹理、河流等区域。其次,结合高并行指令优化策略,提出高性能软硬件协同优化方案,实现多尺度深度图融合算法架构在有限资源FPGA平台的高效运行。最后,将现有CPU方法、GPU方法与FPGA方法进行综合实验比较,实验结果表明:FPGA方法在重建时间消耗上与GPU方法接近,比CPU方法快近20倍,但功耗仅为GPU方法的2.23%。
Abstract:The existing 3D reconstruction methods based on Unmanned Aerial Vehicle (UAV) images cannot meet the mobile terminal's demand for low power consumption and high time efficiency. To tackle this issue, we propose a fast, low-power and high-precision 3D reconstruction method based on resource-constrained FPGA platforms, which combines instruction optimization strategy and hardware-software co-design method. First, we construct a multi-scale depth map fusion algorithm architecture to enhance the robustness of traditional FPGA phase correlation algorithms to untrustworthy areas, such as low-texture area and rivers. Secondly, based on the high parallel instruction optimization hardware acceleration function strategy, a high-performance hardware-software co-design scheme is proposed to realize the efficient operation of the multi-scale deep map fusion algorithm architecture on the FPGA platform with limited resources. Finally, we comprehensively compare the state-of-the-art CPU and GPU methods with our method. The experimental results show that our method is close to the GPU method in reconstruction time consumption, nearly 20 times faster than the CPU method, but the power consumption is only 2.23% of the GPU method.
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Key words:
- low-power /
- FPGA /
- 3D reconstruction /
- phase correlation /
- hardware-software co-design
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表 1 不同软硬件协同优化方案对比
Table 1. Comparison of different hardware-software co-design solutions
硬件资源类型 方案1 方案2 行FFT 列FFT+CPS+列IFFT 行IFFT 总计/% 子图像块提取 行FFT 列FFT+CPS+列IFFT 行IFFT 视差估计 总计/% BRAM_18K/个 12 18 6 34 0 12 18 6 0 49 FF/个 14 849 23 559 7 439 10 1 766 14 718 23 559 7 240 2 431 11 LUT/个 16 811 27 088 8 366 23 2 932 16 452 27 088 8 125 4 745 27 时间/s 8.1 6.4 表 2 不同指令优化策略对比
Table 2. Comparison of different instruction optimization strategies
硬件资源类型 方案1 方案2 方案3 128×128窗口 总计/% 128×128窗口 64×64窗口 32×32窗口 总计/% 128×128窗口 64×64窗口 32×32窗口 总计/% BRAM/Mb 207.5 66.51 20 20 11 70.19 101 38 11 67.31 FF/个 66 047 14.33 38 858 34 804 31 608 39.03 25 955 22 477 19 319 20.41 LUT/个 47 847 20.77 27 963 24 889 23 630 57.73 21 104 18 371 17 098 31.38 时间/s 77.95 19.05 12.85 14.67 47.77 6.75 7.02 8.25 23.1 表 3 基于CPU、GPU、FPGA平台三维重建方法的定量评估结果
Table 3. Quantitative evaluation of 3D reconstruction results based on CPU, GPU and FPGA methods
方法 平均误差 均方根误差 CPU 1.511 0 0.014 9 GPU 1.502 0 0.012 3 FPGA 1.519 5 0.013 1 -
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