If you have ever wondered why some HDR images offer much better results when used for lighting than others, then Hyperlocal Design’s Jay Weston’s post will offer some great information for you.
If you’ve got a HDRI that’s medium dynamic range or its been clamped, essentially it just means it hasn’t been shot correctly
If HDR images are shot correctly, they can be used for a lot more than just ambient lighting. A properly shot HDR can be a really easy way to achieve much more realistic lighting.
An unclamped HDRI should offer strong light and sharp shadows in your scene, behaving much light the effects of standard lights. The reason that unclamped HDRI’s will give you bright sunlight and sharp shadows is that they were shot using enough exposures, and used the correct filters for doing so.
Jay notes that what will happen sometimes with photographers is that they will just snap 3 brackets that don’t really capture the entire range of the sky. This will leave your render with a strong blue cast, weak lighting and shadows, and little dynamic range.
Jay Weston walks us through the differences between the incorrectly shot, clamped, or what he is calling the “medium dynamic range images” and unclamped HDRI’s. There is also a comparative look at the effect they can have in your image based lighting setups.
Visit Hyperlocal Design’s post on the importance of un-clamped HDRI maps and how bad your renders can look if you use low quality, hastily photographed HDRIs.