HDRi sIBL - correct usage?

[voon]

I was looking at the interesting HDRi environment packages here:

http://www.hdri-hub.com/free-samples

Those are free and can be downloaded. I use the "Path" package as an example. The package contains various files:

- A background JPG
- A HDR file called Ref(lection)
- A HDR file valled Env(ironment)

The background jpg is just the plain normal foto (spherically mapped or something to fit the environment sphere).
The Ref file is like the background foto, retaining the sharpness, but overexposed. I guess it is ti highlight the areas producing light. The Env file seems to be the same as the Ref file, but blurred. Also highlighting the areas producing light, but not fuzzy.

In Octane, I went to the Preview Confugration, added an image texture node, loaded the plain background image into it and connected that to the Mesh Preview Environment node ... that produced nice surroundings, but bland.

I added another image node, loaded the Ref file into it and connected that to the power input of the former image texture node. That increased the power (light) in the areas that have more .. it loos less bland now.

I then have to fiddle madly (madly because I'm a newbie and have to trial and error) with gamma, the power sliders of the nodes involved and the exposure of the camera to produce the same effect by various ways.

Is this hiw HDRi sIBL is suppsoed to be used in Octane?

Also: Why is there the Ref file and the Env file, both specifying areas of intense light, but once blurry and once sharp?

And: If I have intense sun in such a hdr environment background .... will that produce sharp shadows like say the daylight environment in octane?

Also: Where's the "bottom" in such environemnts? How would you put the cube in the attachment to the pathes ground and have an according proper shadow, as seen on the website in above link and their various rendered car example images.


Attachment: A simple cube with metal surface inside this path environment

[Rikk The Gaijin]

The blurred one is used if you just need the light. It's smaller because you don't need any fine detail, also will render faster.
The big one is used when you need to see the env reflections in your scene.
The jpg is just a reference, not many image viewer can open HDR files.