Different camera position creates different brightness in IRAY
I have been using Daz3d for a very very very very long time, but, this is the first time I have really hit this (or noticed).
When I was doing an outside scene which has multiple panels, I was taking a shot of the character from the front, and then one from the back. However, I noticed that everything went darker when I was taking the photo from the back.
I couldn't figure out what was going on so I decided to move back to Daz3d 4xx (I use Alpha because I have a 5090) and decided to start a little test to try and understand what was going on - but couldn't figure it out there either.
So to explain what I am seeing, and I am not sure why, and if there is something I am suddenly doing wrong - or I have totally forgot something important about light, Daz3d, IRAY, and Life :D
In picture one the camera is facing towards the light source (distant light), and that shadow is coming towards the camera. In this the brightness of the materials/objects is what I wanted
In picture two the camera is facing away from the light source (distant light), and the shadow is going away from the camera. In this the brightess is way to high, and the only way to fix it would be to reduce the distant light (but of course that impacts the shadow dulling it)
In picture three I have put them together to show the difference.
In my original it was the ground that showed me the difference which isn't really shown here, so I also did the picture 4 and 5 to show that when shadows are there, it darkens the materials/objects when you are facing into the light.
Now this might be light bouncing etc - but - how do you handle multiple scenes then when you are moving around a character because the increase and decrease in brightness doesn't seem realistic to me .... unless I have gone nuts :D
Since I can't seem to work out if there is a way to set up exposure on a camera itself - and it is only scene based - I would assume you can change exposure to fix this, but that would mean loading between different exposures when moving the position. I ... haven't had to do that before.
So - any comments on what I am seeing - or ways to resolve?
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Comments
Of course another way to resolve this - is every time I have to take shots from different camera positions I need to change the Tone Mapping in Render Settings - but of course this is for the whole scene (I so wish this was per camera setting!!!!). So the only way I can figure out how to work around this issue is to match up a render setting preset and then load depending on camera position (facing/notfacing Distant Light source)
Another way is to add additional lights to brighten up the darker - but issue there is it again impacts the shadow and creates more shadows which is what I didn't want to do.
I'm not an expert. I usually use some plugins to set the overall lighting and then fine-tune the options, but I think modifying Tone Maoing's Exposure Valure, Gamma, and Environment's environment intenisity can be helpful in making the contrast between light and shadow in the image less intense.
Thanks - was hoping to not have to do a change of tone mapping/exposure but - I can not see an option. This feels insane though that you can use distant light/HDRI and basically it does this - it feels wrong to me and broken.
What I did was put a plane in front of a new camera, with transparency, but - that really didn't work like I wanted either because - well - the plane creates a shadow :D (doh!)
This is actually the expected/proper behavior for an unbiased render engine like Iray. It's also what happens in real life, it's just "we" don't notice it because our eyes automatically adjust for brightness. Before we had cameras that simply auto adjusted for lighting conditions, we would have to manually adjust a real camera to account for different lighting conditions if photographing a subject from different angles in environments with uneven lighting (a common problem in direct sunlight).
The Iray Auto Exposure Tool in Daz Studio may help you with this problem. I do everything manually, so I don't know if this will help, but it might be worth exploring. You can see how to use it here:
https://www.youtube.com/watch?v=5VAVZPmIQ5M
Thank you DustRider - I don't know why I didn't notice it so much before - but I think this is because it is the first time I have ever really used outside Distant Light - I have typically used studio lights - but I wanted this to have a single shadow etc etc...
I figure I have to create multiple saved Render Setting presets so that I can set the Exposure based on the camera position - ... feels strange having to do that - but well - I ... can't see another real option. While I like the fact that the Auto Exposure looks good - my issue there is it wouldn't really allow for standards - I think what I am thinking is that I need to create presets that will allow more control around the brightness.
Though I am going to play with the whole idea of using White Point - and see if that might help... thanks for the link to the picture.