HDRI Lighting

[crisp109]

So I downloaded some HDRI skies (vismasters website) and I'm trying to use them for lighting my model. When I download the file, I get multiple files and I'm not sure which one to use and I've tried to use them all without success.

HDR_clearbluesky01.exr
HDR_clearbluesky01.hdr
HDR_clearbluesky01_LDR.jpg
HDR_clearbluesky01_LIGHTING.exr
HDR_clearbluesky01_LIGHTING.hdr
HDR_clearbluesky01_PREVIEW.jpg

The .exr files are not an option to use so they are out (not sure what they are). The obvious option would be to use the _LIGHTING.hdr. I've use this file, as well as the others, and I get the same result each time.....a model that appears to not have a light source. I've played with the multiplier as well.

Any advise would be greatly appreciated.

[luchangliang_cg]

Re: HDRI Lighting

Use HDR_clearbluesky01.hdr in your GI and enviroment texture, and set the multiplier to 10000 or more, then u can see the result.

[crisp109]

Re: HDRI Lighting

That's exactly what I have and it isn't producing the results it should. The UVW is set to environment with the mapping set to spherical. I've tried to rotate the HDR horizontally but nothing. In my global switches, under lighting, I have tried selecting and de-selecting the "Show GI only" as well as the other options.

I don't know what's going on.

[dalomar_cg]

Re: HDRI Lighting

There are two things to this, so I'll answer your indirect question of "why this isn't working" first....

In the default settings, we have the physical camera and the physical Sun/Sky enabled. What this means is that the environment and exposure setting of the scene are setup for a very bright environment. Run-of-the-mill images don't have the proper intensity values to work well in this environment, so subsequently they will turn out black. There are two possible fixes, the first is to increase that intensity until the image shows up and has an effect on the render, which can be anywhere from 100 to 10000, so you'll have to figure out the correct value via trial and error. The second possible fix is to change the environment by removing the physical camera and the sun/sky. Once you do that, then your images should appear as normal.

The second question of which one to use is a little bit more straight forward. First off, you've got two main classifications within those images...LDR (low dynamic range) and HDR (high dynamic range) with the jpgs being LDR and the exrs/hdrs being HDR. The LDR images are typically only there so that you can browse the image without having to open up photoshop or something (the PREVIEW one is probably just at a screen resolution).

The second distinction is the purpose of the image. Although you can just have one image for both lighting and background/reflections, its actually better to use two separate versions of the HDR. One for background/reflections that is the original and is sharp, and a blurred version of the image for lighting. The blurring helps generate smoother images, but most importantly allows the lighting to typically be computed faster.

[crisp109]

Re: HDRI Lighting

Dalomar, I've played with the multiplier from 100-100,000 and continue to get the same, no shadow image. I haven't run into getting just a black screen. The model is lit but there is no directional lighting point. Tested many times with the physical camera on.

I tried to turn off the physical camera, but this only makes my materials that have reflection, super pixelated (spotty shiny)...glass is no longer transparent because there is so much reflection....and I get the GI hot spots all over the model.

[crisp109]

Re: HDRI Lighting

Ok, I've been able to get my lighting to work with the physical camera turned off (reflections are fine). I'm still getting the GI hot spots on the rendering in various different places. On my Irradiance map settings, I've set the min rate to -3 and my max to 1. My secondary engine is quasi-monte carlo GI and those are set to 8, 3. What can I do to get rid of the hot spots?

[dalomar_cg]

Re: HDRI Lighting

Can you post an image of what your seeing?

It should be noted that professional HDRS tend to have a lot of Dynamic Range. This is a good thing, but what that usually means is that the images are brighter than expected. This may be why you're getting those hotspots, in which case, lowering the multiplier slightly might be a course of action.