I have read and experimented with HDR equirectangular photos for backround lighting and I’ve come to the conclusion that, being such huge, difficult to produce files, the benefits are not worth the problems. I can achieve the same effects with a good 8bit JPG and a sunlamp or area light and have better control over the final results.
I find that a good outdoor equirectangluar JPG does illuminate the objects in the scene, and the sun in the photo will cast subtle, soft shadows, so when I add a sun lamp (lined up with the photo sun), shadows have a proper soft blue light fill. I understand that with an HDR, using the proper math nodes, I can get sharp shadows without the sun lamp, but I do not see any advantage, given the disadvantages of HDR photos, and given the ease of using the sun lamp.
I’d be interested in learning reasons why I might be wrong. Thanks for any clues.