EV at 0.

[piotrus3333]

Recently I've been setting my camera to 0 EV and instead just increasing/decreasing the output of my HDRI lighting map to render.

so you will put that multiplier into every additional artificial light? if you went through the hassle of matching hdris to roughly real life values leave them at 1. dont waste hard work. iso/ev will not affect your mb/dof. use that. it’s just easier.

[Neilg]

That workflow is exactly how people worked before the physical cameras and exposure control was introduced, it's not that weird.
I dont really use camera exposure settings - we expose all lights to an un-exposed perspective viewport and if needed because a camera is animated bring in exposure control. But the first number we start from is an EV which matches the viewport, not a real-world value.

[piotrus3333]

sure, people used to do a lot o things differently. but people learning today should be pointed straight to just referencing reality - this is how things are being done now. shortcuts are good.

[DanSHP]

I may have contradicted myself a little here, apologies, but I've moved on from my initial post (maybe I should start a new one) to HDRI calibration, but whilst you're all here....

It goes like this. I work in house at an architectural practice and I'm often asked to produce renders of facades in different lighting conditions (usually all glass with fritted patterns), and as these renders are instrumental to the design process I really need/want to get to a point where I can say "this is physically accurate (as technology permits)".I thought using a grey card alone to expose my scene alone would be a way forward, but I've since come full circle.

I've followed dubcats calibration tutorial on the corona forums to calibrate my HDRI's.
https://corona-renderer.com/forum/in...?topic=10190.0

So a few things. My modelling (or imported revit model) is right. I've nailed down the theory of PBR so I know my materials are right. My HDRI's are calibrated (left at 1 multiplier in vray) so I know they are now right too. Now, it's just my camera exposure to think about.

I use EV as it's one value to change, rather three (Fstop/Iso/ShutterSpeed). If I want DOF/Motion blur, I can just enable it and play around with values until I'm happy without affecting the exposure in my scene. I've just tested one of my high noon calibrated HDRI's, yet I'm having to lower the EV to 4 to get enough light in my scene. Going from EV charts, a high noon sunny day setting should use around 15-16 EV.

What am I missing here?

I should add I'm doing all of this in Corona!

[DanSHP]

..............

[DanSHP]

I'm thinking physical camera EV does not work with corona the same way it does Vray, or the camera is not supported? Gah...!

[piotrus3333]

heh, wrong forum.
anyway, just compare the lighting from map to that from sun and sky system on a simple scene and adjust output multiplier to match it roughly, no need for crazy precision here.

one thing I can tell you - if your map has severe glare as the one in the link - remove it first in ps to get nice sharp shadows.
this is 1123 sun clouds, PG, from few years back. I know those were redone at some point, do not know what was adjusted. rendered with 0.75 gamma adjustment. before and after removal of glare around sun:

[DanSHP]

I know. I just love you guys too much and I would of thought it was all relative in terms of this subject matter.

Adjusting the gamma value affects the colours of the Hdri though right? Making it look unnatural. Calibrating the Hdri avoids that I understand.

Edit: Oh you mean output multiplier. Not gamma?

[piotrus3333]

gamma. old days, trick to get better shadows from maps with not high enough dynamic range.

[DanSHP]

After looking up EV in Corona it seems, it doesn't work with traditional EV tables. I can essentially (as long as my HDRI is calibrated and left a 1, after being aligned and calibrated to virtual sun multiplier of 1) change the EV to what ever I like! Usually 2-3 -EV