针对卫星图像小船检测,通过调整特征层级实现更高效精准的定位。
LiM-YOLO: Less is More with Pyramid Level Shift for Ship Detection in Optical Remote Sensing
- 将检测头从32倍下采样改为16倍,避免细长船只信息丢失。
- 模型参数减少64%,在四个数据集上达到0.600 mAP50:95。
- 适合资源受限场景下的高精度遥感船舶检测应用。
通用目标检测器在卫星图像船舶检测中面临结构局限,因船舶尺寸集中于小尺度且高宽比大。传统YOLO架构中,最深层特征金字塔(步长32)会将细长船只压缩至亚像素,导致空间特征稀释,影响边界回归精度。我们提出LiM-YOLO,基于YOLOv9超大版本,通过统计分析四个主流基准(SODA-A、DOTA-v1.5、FAIR1M-v2.0、ShipRSImageNet)的船舶尺度分布,引入金字塔层级迁移策略,将检测头从步长8、16、32调整为4、8、16。该调整满足奈奎斯特-香农原理对最窄目标的空间表征要求,同时消除最深层冗余计算。为应对高分辨率输入下的训练不稳定性,引入组归一化复合骨干投影模块,在内存受限的小批量训练中有效缓解梯度波动。在四大数据集上验证,模型仅用2116万参数,即达0.600 mAP50:95,较YOLOv9-xl基线(5899万参数)减少64.1%。尽管体积紧凑,性能仍超越三倍大小的先进检测器,验证了针对性金字塔调整实现“少即是多”的精度与效率平衡。代码已开源。
原文摘要 · Abstract (English)
General-purpose object detectors face fundamental structural limitations when applied to ship detection in satellite imagery, where the ship scale distribution is concentrated at small sizes and high aspect ratios. In conventional You Only Look Once architectures, the deepest feature pyramid level (stride 32) compresses narrow vessels into sub-pixel representations, causing severe spatial feature dilution and compromising accurate ship boundary regression. We propose Less is More YOLO, a streamlined detector built upon the extra-large variant of YOLOv9, to address these domain-specific structural conflicts. From a statistical analysis of ship scale distributions across four major benchmarks (SODA-A, DOTA-v1.5, FAIR1M-v2.0, and ShipRSImageNet), we introduce a Pyramid Level Shift Strategy that shifts the detection head from strides 8, 16, and 32 to strides 4, 8, and 16. This shift satisfies a spatial representability condition derived from the Nyquist-Shannon principle for the narrowest targets, while eliminating the computational redundancy of the deepest pyramid level. To further stabilize training on high-resolution satellite inputs, we incorporate a group-normalized composite-backbone projection module, mitigating gradient instability in memory-constrained micro-batch regimes. Validated on these four datasets, our detector attains an mAP50:95 of 0.600 with only 21.16 million parameters, a 64.1% reduction from the extra-large YOLOv9 baseline (58.99 million). Despite this compact size, our model surpasses state-of-the-art detectors up to three times larger, validating that a well-targeted pyramid level shift achieves a "Less is More" balance between accuracy and efficiency. The code is available at https://github.com/egshkim/LiM-YOLO.
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