Changing exposure value/shutter speed in viewport(iray)

Mr_Fluffkin

There seems to be a bug with changing the exposure value/shutter speed while rendering with iray inside the viewport. Whenever i change one of the two values, the scene becomes almost black, until i switch back to another drawstyle(texture i.e.) and again back to iray. Then i get the correct lighting, but it always needs this "reset" of the drawstyle after changing the values, it doesnt work "on the fly". Is this a known issue?

My Daz Studio is the newest Version.

Mr_Fluffkin

Well, i just rechecked and recognized that the sliders cause this(vignetting as well). If i type the values by keyboard everything works fine, if i use the sliders its bugged. So this is an easy workaround. ;)

Richard Haseltine

I see this only if I end up with a negative shutter speed. Exposure value easily ends up too high or low, producing black or white, but dragging it back into a sensible range restores things.

Mr_Fluffkin

I was working with a negative horizon height(-5), but shutter speed/exposure values close to the defaults and positive. As soon as i moved the slider even a mini step, everything got black, except of 1 little spot with light in the bottom left part of the scene, which looked like i would use a super heavy, not centered vignette. If i undid and typed the exact same value i set with the slider before, everything worked fine.

Richard Haseltine

Could you provide a scene set up to show the effect?

Mr_Fluffkin

Sure. This is my scene, its just the plain https://www.daz3d.com/prison-exercise-yard, nothing else. Just in case you wanna rebuild it, but the assets definetly don´t matter, as i encountered the same behaviour on completly different scenes. These are my tone mapping and render settings, everything else is default(filtering, optimization etc.):

Tone Mapping:

Render settings:

In drawstyle iray, it looks like this, everything is fine:

Now if i change the vignetting from 10 to 9.61 on the fly via slider(same with exposure/shutter speed, the result looks always exactly the same), the viewport shows this:

And if i type the same vignette value(9.61) by keyboard instead(or switch the drawstyle to smth else and back to iray without changing anything), it looks how it should again:

Hope this helps. Its not a problem if you know the workaround, but can be quite frustrating for people who dont, and who think they have to switch the drawstyle over and over again to work around the bug. Like me till i found out. :P

Richard Haseltine

A saved scene file (with just a primitive sphere would do) would make it easier to be sure I had the correct settings.

Mr_Fluffkin

Well, than i misunderstood you. Here we go, same settings with a primitive instead of the prison yard: https://easyupload.io/uk7gev

Richard Haseltine

I don't have the HDRI used, but just letting it do a Sun/Sky I don't see the issue. Does it hapen for you with other HDRs?

Mr_Fluffkin

Maybe i misunderstand you again, but the scene has no HDRI? It´s sun-sky only, isn´t it? If i open the duf file it´s straight sun-sky without any HDRI. I also think it only happens with sun-sky mode, at least all scenes where i encountered this were sun-sky only.

Richard Haseltine

Ah, there is a bug with the HDRI reverting in scenes using Sun Sky - I guess it reverted to the last one used rather than to the default.

and trying it again today I do see what you are seeing with the localised bright spot - not sure why it wasn't showing yesterday, perhaps lack of patience. Please report this as a possible bug, attaching your scene file.