How to light up interiors using HDRi's?

Aala

This is a problem that I've been encountering lately on my renders, and I don't really know how to solve it. Basically, using only HDRi' maps, I can't seem to know how to light up interiors without making the HDRi map itself overly bright. Here's an example:

(Sorry for the grain, was a quick render.)

As you can see, even though it's very bright outside the environment (Stonemason's Pool Houe), inside it's quite dark because I suppose not enough light is coming in. The HDR itsel I got for the HRD labs titled Malibu Overlook. I even added a spherical mesh light to act as a sun that I can control, but other that making the ouside quite birght, I still can't achieve what I want.

If I go into the environment tab under render settings and fiddle with the environment intensity and map settings, I can't find a decent setting that doesn't oversaturate the HDR map outside, it becomes so bright that it loses all detail, and I can't find any decent setting under tone mapping either that could do what I want to do.

Now, I know that this is supposed to be realistic, it's how light behaves, but I also feel that the light coming from outside should flood the space inside since it has so many large windows. I don't think this is what our eyes would see in such a scene. So my question is: Is there a way to enhance the the light in the interior without resorting to artificial means? I don't wanna set up fake lights just so I can see my characters within this space...

Oso3D

The image is realistic. The thing is, our eyes adjust when we look toward the bright bits, then again when we look in the shadow. Mentally, we're essentially brightening the low tones and dimming the high tones.

So, I'd suggest doing that in post, using Curves or similar.

 

Aala

timmins.william said:

The image is realistic. The thing is, our eyes adjust when we look toward the bright bits, then again when we look in the shadow. Mentally, we're essentially brightening the low tones and dimming the high tones.

So, I'd suggest doing that in post, using Curves or similar.

 

Yeah, I guess post is the only way. I've actually been thinking on doing the HDR trick where you render an image in three different tone settings and then merge them, but still... this is what I want to achieve:

And I don't really know how to go on abou it... :/

Horo

HDRIs in general are on a big sphere and create lights in an environment. They are therefore outside and only shine through the openings of the structure - the windows and doors. Looking at it from this angle, your render looks quite natural. You have to add lights inside the room. If you move the camera out of this very nice room, you will see that its outside is lit.

mjc1016

It's not what our eyes would see...but it is close to what a camera without any auto functions would see.

You need to play around with the tonemapping settings to strike a good balance.

Aala

Horo said:

HDRIs in general are on a big sphere and create lights in an environment. They are therefore outside and only shine through the openings of the structure - the windows and doors. Looking at it from this angle, your render looks quite natural. You have to add lights inside the room. If you move the camera out of this very nice room, you will see that its outside is lit.

You're stating the obvious though. I know that, but what I mean is how should I go on about to try and render interiors using HDRi's without making the HDRi look like the sun is glaring from your window? I don't want to light it up from the inside, or use postwork, that's my point...

mjc1016 said:

It's not what our eyes would see...but it is close to what a camera without any auto functions would see.

You need to play around with the tonemapping settings to strike a good balance.

You have any idea what settings I should use?

mjc1016

Adjusting the fstop and/or ISO values...probably bump up to 400 ISO and then play with the f-stop to stop the inevitable blowout...

Oso3D

I don't know if that's going to really help, because the problem is the range of lighting more than the amount.

However, when I want realistic lighting, a good approach:

In Tone Mapping, turn Burn Highlights per Component OFF, Burn Highlights 1, and Crush Blacks 0. Then adjust lighting/ISO to get the exterior as bright as possible without blowing out. THEN do the rest in post.

My advice.

 

 

mjc1016

timmins.william said:

I don't know if that's going to really help, because the problem is the range of lighting more than the amount.

However, when I want realistic lighting, a good approach:

In Tone Mapping, turn Burn Highlights per Component OFF, Burn Highlights 1, and Crush Blacks 0. Then adjust lighting/ISO to get the exterior as bright as possible without blowing out. THEN do the rest in post.

My advice.

 

 

I keep forgetting you need to adjust those in Iray...in Lux it's just the tonemapping/exposure.

Knittingmommy

I would start by putting the Film ISO at 800 and start from there going up. 400 and down usually darkens the image by letting less light in.  These are my favorite cheat charts which should help to get you started.  Basically, the higher the number the longer the exposure the more light gets let in.

frogimus

bloom might help some too

mjc1016

The nice thing is, you don't have to worry about some of the problems with film...graininess at higher speeds (ISO  100 and 1600 have no problems).  Just like everything will remain perfectly still so long exposure times don't matter either.

I found 400 is a good start, for rendering though...

Horo

Aala - I'm sorry that I haven't been helpful. Here is another unhelpful suggestion: keep gamma at 1, make a couple (4 or so) of renders with different light settings (doubling or halving light for each render), the assemble the renders to an HDRI and tone-map it (Picturenaut is a free program that can be used). In other words, do it the same way as you would photograph for an HDRI. If one render takes a couple of hours, that's probably not the best solution. However, I did this several times successfully. 

 

Oso3D

I prefer not to mess with ISO unless I have emissive objects in mutliple scenes or standardized lighting.

Iray likes more light to render properly anyway, so I'd rather just up light levels.

 

Fishtales

Try this.

Use the Architectural Sampler on the interior walls and ceiling.

Put a distant light shining through the glass window on the right, as the sun, raising it and moving it left or right until you get the light you want.

Adjust the Tone Mapping settings and the Intensity of the Distant Light until you balance the light inside with the Dome image.

j cade

The problem is also twofold. For one, in the real world, if you take a photo of a brightly lit interior lit only by natural light, the window is going to end up pretty blown out. This is also compounded by the fact that iray isn't great at lighting purely via windows (I think turning architectural on in render settings helps, but what we really need are portals.)

 

I'd try what fishtales suggested, particularly the bit about adding a distant light.

 

But, if that doesn't work, and you want the hdr image not blown out you're probably going to need to do some postwork, in particular do a render with draw dome set to off in the render settings, and then render the backdrop seperately

Horo said:

Aala - I'm sorry that I haven't been helpful. Here is another unhelpful suggestion: keep gamma at 1, make a couple (4 or so) of renders with different light settings (doubling or halving light for each render), the assemble the renders to an HDRI and tone-map it (Picturenaut is a free program that can be used). In other words, do it the same way as you would photograph for an HDRI. If one render takes a couple of hours, that's probably not the best solution. However, I did this several times successfully. 

 

If you enable canvases in render settings it will save out a hdri automatically (an exr to be precise) so you only have to render things once you can then do all the hdri editing you want, it has definitely come in handy for me.