colors - 计算日光的预期色温

Question

我有一个位置(纬度/经度)和一个时间戳(年/月/日/小时/分钟)。

假设天空晴朗，是否有算法可以粗略估计当时和地点的阳光色温？

如果我知道当时的天气情况，有没有建议的方法可以根据当时的云量来修改色温？

Answer 1

我建议看看this paper它对 CG 应用程序有很好的实际实现:

A Practical Analytic Model for Daylight A. J. Preetham Peter Shirley Brian Smits

Abstract

Sunlight and skylight are rarely rendered correctly in computer graphics. A major reason for this is high computational expense. Another is that precise atmospheric data is rarely available. We present an inexpensive analytic model that approximates full spectrum daylight for various atmospheric conditions. These conditions are parameterized using terms that users can either measure or estimate. We also present an inexpensive analytic model that approximates the effects of atmosphere (aerial perspective). These models are fielded in a number of conditions and intermediate results verified against standard literature from atmospheric science. Our goal is to achieve as much accuracy as possible without sacrificing usability.

Both compressed postscript and pdf files of the paper are available.

Example code is available.

Color images from the paper are shown below.

不鼓励仅链接答案，但我不能在这里发布足够的文章部分或任何完整的 C++ 代码片段，因为两者都太大了。按照链接，您现在可以找到两者。