Ever present and helpful, thank you.
The way I've understood this in the past, and the excerpt below is one example, I apparently misunderstood it to mean that the radiance/luminescence that is stored is light source information.
"Information stored in high dynamic range images usually corresponds to the physical values of luminance or radiance that can be observed in the real world. This is different from traditional digital images, which represent colors that should appear on a monitor or a paper print. Therefore, HDR image formats are often called "scene-referred", in contrast to traditional digital images, which are "device-referred" or "output-referred". Furthermore, traditional images are usually encoded for the human visual system (maximizing the visual information stored in the fixed number of bits), which is usually called "gamma encoding" or "gamma correction". The values stored for HDR images are often linear, which means that they represent relative or absolute values of radiance or luminance (gamma 1.0).
HDR images require a higher number of bits per color channel than traditional images, both because of the linear encoding and because they need to represent values from 10−4 to 108 (the range of visible luminance values) or more. 16-bit ("half precision") or 32-bit floating point numbers are often used to represent HDR pixels. However, when the appropriate transfer function is used, HDR pixels for some applications can be represented with as few as 10–12 bits for luminance and 8 bits for chrominance without introducing any visible quantization artifacts.[6]"
Source:
http://en.wikipedia.org/wiki/High_dynamic_range_imaging
I do understand the process, in general. I took my photo of the sky with sharp, bright clouds, using -2, 0, and +2, which is all my wife's camera could handle (she wouldn't let me buy the nicer, more professional one :frown: ). I then put it in Photoshop and bounced out the .hdt, which, of course is not usable in Cheetah3D. I'm merely trying to get that sucker in Cheetah3D, without having to buy more stuff.
Now, if I apply the new image to the HDR tag in any way, it comes out blank (as expected). If I apply it to a sphere and put my scene in side it (as I did with the River Bank scene I posed in the Gallery section), it will work. That's obviously not the way to go. Meanwhile, it appears that HDRI helps to point lighting from the appropriate directions and at the appropriate intensities. Regardless of how this comes out, I'm very happy with the information that all of you have provided. It has been an education.