用事件相机重建静态场景,突破传统图像方法限制。
ESAR: Event-Based Synthetic Aperture Reconstruction
- 将事件数据建模为合成孔径反问题,直接恢复场景辐射场。
- 在真实和模拟数据上恢复出清晰的大尺度结构,纹理更少。
- 适合做事件相机低延迟、高动态场景重建的研究者。
事件相机在对数亮度变化超过阈值时异步输出带符号的时间对比事件,而非传统图像帧。本文将单目事件成像建模为静态地面域对数辐射场 $θackepsilon \mathbb{R}^{N_g}$ 的合成孔径逆问题。不同于重建潜在像素-时间体积 $v \backepsilon \mathbb{R}^{N_pN_t}$,我们引入几何关系 $v=Pθ$,其中 $P$ 将固定场景映射为与运动相关的潜在视角。对有限时间区间内事件进行聚合,得到线性化模型 \\[ APθ= b+η, \\[ 其中 $A$ 为时间差分算子,$b$ 包含带符号的事件计数,$η$ 表示测量与建模误差。该分解揭示了合成孔径结构:在近垂直运动下,连续投影近似为同一场景的位移视图,而复合算子 $AP$ 因结合空间平均与时间差分仍为病态。因此采用正则化反演恢复 $θ$。在模拟数据和真实的近垂直 Falcon Neuro 事件数据上的数值实验表明,所提出的基于 $θ$ 的方法相较于动态潜在图像和学习型事件重建基线,能更好地恢复连贯的大尺度空间结构,同时抑制细粒度纹理。
原文摘要 · Abstract (English)
Event cameras report asynchronous polarity events when changes in log--radiance exceed a fixed contrast threshold, producing signed temporal contrast measurements rather than conventional image frames. We formulate monocular event-based imaging as a synthetic-aperture inverse problem for a static ground-domain log--radiance field $θ\in \mathbb{R}^{N_g}$. Instead of reconstructing a latent pixel-time volume $v \in \mathbb{R}^{N_pN_t}$, we impose the geometric relation $v=Pθ$, where $P$ maps the fixed scene into motion-dependent latent views. Aggregating events over finite time intervals gives the linearized model \[ APθ= b+η, \] where $A$ is a temporal differencing operator, $b$ contains signed binned event counts, and $η$ represents measurement and modeling errors. This decomposition exposes a synthetic-aperture structure: under near-nadir motion, successive projections are approximately shifted views of a common scene, while the composite operator $AP$ remains ill-conditioned because it combines spatial averaging with temporal differencing. We therefore use regularized inversion to recover $θ$. Numerical experiments on simulated data and real near-nadir Falcon Neuro event data show that the proposed $θ$-based formulation recovers coherent large-scale spatial structure, relative to dynamic latent-image and learned event-reconstruction baselines, while suppressing fine-scale texture.
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