提升无人机图像分割速度与能效,实现旋转不变性
Accelerated Rotation-Invariant Convolution for UAV Image Segmentation
- 通过结构化数据共享优化旋转不变卷积,减少内存开销
- 在256×256输入下速度提升45%,能耗降低41%
- 适配任意旋转角度,可集成至U-Net提升分割精度
旋转不变性对无人机航拍图像中的目标级分割至关重要,因目标方向任意且细节精细。传统U-Net等架构依赖非旋转不变卷积,导致视角变化时精度下降。虽可通过多方向滤波器扩展实现旋转不变性,但会显著增加计算开销与内存流量。本文提出一种面向GPU优化的旋转不变卷积框架,摒弃传统im2col数据展开步骤。通过利用对称旋转滤波器间的结构化数据共享,大幅降低内存访问与计算冗余。方法进一步推广至任意(非对称)旋转角度。在多个基准测试中,该卷积比CUDNN快20–55%,能耗低15–45%;在八方向设置下,256×256输入上速度提升45%、能耗降41%,1024×1024输入上提速32%、能耗减23%。集成至U-Net后,分割精度较非旋转感知基线最高提升6%。结果表明,该方法为现有旋转不变CNN框架提供了高效且有效的替代方案。
原文摘要 · Abstract (English)
Rotation invariance is essential for precise, object-level segmentation in UAV aerial imagery, where targets can have arbitrary orientations and exhibit fine-scale details. Conventional segmentation architectures like U-Net rely on convolution operators that are not rotation-invariant, leading to degraded segmentation accuracy across varying viewpoints. Rotation invariance can be achieved by expanding the filter bank across multiple orientations; however, this will significantly increase computational cost and memory traffic. In this paper, we introduce a GPU-optimized rotation-invariant convolution framework that eliminates the traditional data-lowering (im2col) step required for matrix-multiplication-based convolution. By exploiting structured data sharing among symmetrically rotated filters, our method achieves multi-orientation convolution with greatly reduced memory traffic and computational redundancy. We further generalize the approach to accelerate convolution with arbitrary (non-symmetric) rotation angles. Across extensive benchmarks, the proposed convolution achieves 20--55% faster training and 15--45% lower energy consumption than CUDNN, while maintaining accuracy comparable to state-of-the-art rotation-invariant methods. In the eight-orientation setting, our approach achieves up to 45% speedup and 41% energy savings on 256\(\times\)256 inputs, and 32% speedup and 23% lower energy usage on 1024\(\times\)1024 inputs. Integrated into a U-Net segmentation model, the framework yields up to 6% improvement in accuracy over the non-rotation-aware baseline. These results demonstrate that the proposed method provides an effective and highly efficient alternative to existing rotation-invariant CNN frameworks.
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