发表机构
Columbia University（哥伦比亚大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文提出一种全向辐照度相机，利用球谐函数前七阶近似，仅需少量探测器即可精确重建辐照度函数，实现低功耗与隐私保护，并展示了其在旋转计算、工作空间监控、漫反射重照明和太阳能板朝向估计等应用。
AI 中文摘要
传统相机使用数百万像素来测量其视场内所有方向的辐射度。我们提出了一种全向辐照度相机，用于测量辐照度函数——即照射到球面上每一点的照明。辐照度函数在球面上平滑变化，因此是带限的。我们在频域中分析了该函数，并证明它可以由球谐函数的前七阶加权和很好地近似。因此，辐照度函数可以由少量样本精确重建。这意味着辐照度相机不需要数百万个探测器（像素）——只需少量测量即可。这带来了两大好处。首先，该相机能耗极低，可以完全由照射到其探测器上的光供电。其次，它不捕获识别个体所需的视觉细节，因此保护了隐私。我们构建了一个名为FluxCam的辐照度相机原型，使用49个探测器布置在球体表面。在照明良好的室内环境中，FluxCam可以利用从照射到其上的光中收集的能量（即无需电池、电缆或外部电源）以每秒30帧的速度读出并无线传输其测量结果。我们展示了FluxCam如何用作计算旋转的光学陀螺仪、监控工作空间、作为用于漫反射重照明的无束缚光探针，以及作为用于估计天空状况和确定太阳能电池板最佳朝向的全向日射强度计。
英文摘要
A conventional camera uses millions of pixels to measure radiance from all directions within its field of view. We present an omnidirectional irradiance camera that measures the irradiance function---the illumination incident upon every point on a sphere. The irradiance function varies smoothly over the sphere and hence is bandlimited. We have analyzed this function in the frequency domain and have shown that it is well approximated by a weighted sum of the first seven degrees of spherical harmonics. As a result, the irradiance function can be accurately reconstructed from a small number of samples. This implies that an irradiance camera does not need millions of detectors (pixels)---just a handful of measurements suffice. This brings two major benefits. First, the camera consumes such little energy that it can be completely powered by the light falling on its detectors. Second, it does not capture the visual details needed to identify an individual, and hence privacy is preserved. We have built a prototype irradiance camera, called FluxCam, using 49 detectors arranged on the surface of a sphere. In a well-lit indoor environment, FluxCam can read out and wirelessly transmit its measurements at 30 frames per second using energy harvested from the light falling on it (i.e., without a battery, cable, or external power supply). We show how FluxCam can be used as an optical gyroscope for computing rotation, to monitor a workspace, as an untethered light probe for diffuse relighting, and as an omnidirectional pyranometer for estimating sky conditions and determining the best orientation of a solar panel.
Comments18 pages, 18 figures. SIGGRAPH Asia '26
