Direct HDR capture of the sun and sky

We present a technique for capturing the extreme dynamic range of natural illumination environments that include the sun and sky, which has presented a challenge for traditional high dynamic range photography processes. We find that through careful selection of exposure times, aperture, and neutral density filters that this full range can be covered in seven exposures with a standard digital camera. We discuss the particular calibration issues such as lens vignetting, infrared sensitivity, and spectral transmission of neutral density filters which must be addressed. We present an adaptive exposure range adjustment technique for minimizing the number of exposures necessary. We demonstrate our results by showing time-lapse renderings of a complex scene illuminated by high-resolution, high dynamic range natural illumination environments.

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