Trying to brighten up HDRI image background

[philvanderloo]

I've tried 3 or 4 different HDR images for my exterior scene and I keep getting a very dark background image. Everything I change brightens up the building but the sky and lighting don't change. I bring the images into the material editor, (VrayHDRI texture), mapped to spherical, dragged it to the dome light texture and the environment slot.

 

If I change the dome light or Vray sun intensity the building gets blown out but the background stays the same.

If I change the aperture or ISO the image does brighten up but the white trim in the building blows out again, (all blue). Even after increasing the subdivs in the dome light. Still blown out.

 

Tried increasing the overall multiplier and render multiplier in the material and I get a very slight change. After going past 2 in the render multiplier nothing changes. Decreased the inverse gamma and the building blows out and the background is still dark.

So, to end this long winded question, how can I brighten up my background HDR images without blowing out the building?. Thanks

 

[tomekmiksa]

Check if you have visibility checked with hdri vray light Phil.

[Stephen Thomas]

I would turn off your Vray sun for a start, just deal with one variable at a time. Adjust the HDRI or dome light multiplier to get illumination you want, how does the background look now? Are you having the same problem with other HDRIs?

[Chris MacDonald]

Agreed with the above. Start with just one light - your HDRI, and get your scene lit properly with that first. Then you've got a decent starting point.

[Nicolai Bongard]

As mentioned above, stick to the HDRI only first. The problem i think you are having now is that the HDR illuminates the scene, and then you have your vray sun that adds additional light to you model, but the vray sun does not affect what you see as the background (hdri), thus the model(geometry) in your scene will be illuminated more/the background will appear too dark. The gamma adjustment in the HDR is there to boost the sun intensity compared to the rest of the hdr, so if you do not get as strong shadows as you want with the default value (1), try to lower it to around 0,75. With this "trick", you should not need the additional vray sun to get strong shadows, and your image will look more coherent straight out of the box so to say, instead of having to adjust the sky in post. Hope this made some sense. Good luck!

[Chris MacDonald]

It's also worth noting that not all HDRI's are meant to produce strong shadows; an overcast one is going to be MUCH more diffuse light than a clear sky one. It's what makes HDRI lighting look that much more convincing. Not everything requires razor sharp shadows.

[CliveG]

I think that Phil is asking a slightly different question than is being answered, less to do with the scene lighting, than the brightness of the HDRI as an environment background.

 

If that's so then I'd suggest that the very fact it's an HDRI may answer your question, as an HDRI contains much more light information than a simple (low dynamic range) image, therefore when you increase or decrease the multiplier the HDRI is less visually reactive to those changes, because of all of that extra light information in the file - it works over a larger range.

 

Perhaps if you simply take the HDRI into Photoshop and flatten it to a jpg or similar and bung that in your environment slot and keep your HDRI in the dome, you'll see a more representative reaction to the changing light exposure.

 

Be sure to map it similarly (you can still use the VrayHDRI loader by the way) and I think you'll perhaps see more the reaction to the background that you were expecting.

[Chris MacDonald]

The problem is that he's doubling up on his lighting by using a VRay sun, and the background thus isn't representative of that. Get rid of the VRay sun and set the exposure correctly and it'll look fine.

[geokasot]

I also believe that the vraysun is the problem.You are using the vray dome light and the vray sun as light sources and the vrayhdri mtl as environment background.I suggest that you turn off the vraysun and if you still have the same problem, modify in photoshop the exposure of the sun of the hdri. You can do it in low 32 bit exposure by selecting the sun and adjusting the exposure of the selected area.

[RyderSK]

The problem is that he's doubling up on his lighting by using a VRay sun, and the background thus isn't representative of that. Get rid of the VRay sun and set the exposure correctly and it'll look fine.

 

As mentioned above, stick to the HDRI only first. The problem i think you are having now is that the HDR illuminates the scene, and then you have your vray sun that adds additional light to you model, but the vray sun does not affect what you see as the background (hdri), thus the model(geometry) in your scene will be illuminated more/the background will appear too dark.

 

 

This.

 

I've tried 3 or 4 different HDR images for my exterior scene and I keep getting a very dark background image. Everything I change brightens up the building but the sky and lighting don't change. I bring the images into the material editor, (VrayHDRI texture), mapped to spherical, dragged it to the dome light texture and the environment slot.

 

Actually there are 3, not 2 issues ;- ) He overcomplicated what he could:

 

Issue 1) VrayHDRi (with default multiplier 1) in DomeLight (defaultmultiplier=30) ---) Contributes to scene lighting by taking default texture intensity, multiplied by VrayHDRi intensity, and lastly by Domelight intensity

 

Issue 2)VrayHDRi inside EnvironmentSlot (default multiplier 1) --- ) Doesn't contribute anymore to lighting but intensity doesn't possibly align to Domelight, let alone Domelight + VraySun

 

Issue3) VraySun at default intensity, adding to light information from DomeLight.

 

Quick solution: Keep two versions of VrayHDRi map, and adjust intensity separately, that's what you're after.

Correct quick solution: Don't use such complicated setup unless advanced user. Keep single Domelight. Nothing else.

 

 

I understand Vray is confusing, which this discussion perfectly illustrates, but the original author should just follow A to Z SINGLE tutorial and not all random ones he saw because obviously it's not working well.

Or just use some premade scenes from Evermotion, it works, no need to be ashamed of that. Don't complicate your life more than is needed.

Edited November 12, 2014 by RyderSK