occasionally image is badly clamped

[simmsimaging]

Using the latest beta: occasional renders are coming out oddly clamped - see below:



That is rendered using the "render" button, not the Octane viewport, but it has happened several times now with the Octane viewport and the render route. The saved EXR file looks like that too, so it's not just a viewport problem with the framebuffer.

It should look more like this (super lo-res render, but you can see the brightness as it should be).



Both renders are still actually clamped (no >1 values to be found in Photoshop, but the first one looks really messed up too. Is there a bug going on here? Both are rendered with PMC, nothing fancy.

[Karba]

What imager settings do you use?

[simmsimaging]

I was using the camera settings (Octane camera is the render cam) but I included the f10 dialog settings too. Are those relevant?

[simmsimaging]

ONe correction: the camera tone-mapping was set to the Agfa preset for those two renders. I switched to linear afterwards but forgot to reset it for the screen capture. Not sure it matters.

[Karba]

ONe correction: the camera tone-mapping was set to the Agfa preset for those two renders. I switched to linear afterwards but forgot to reset it for the screen capture. Not sure it matters.

Try to use default imager settings and proper light power.

[simmsimaging]

I am not sure now what the default settings are, or why should these matter? I did try a few other options and (various imager settings and light power) but it seems to be rendering fine at the moment, so can't tell if it's fixed or not.

[simmsimaging]

Tried it with the tonemapping applied and turned off and the renders seem to be the same to my eye. It still looks clamped, but there is not an option to turn off the tone mapping from the camera controls, so maybe it's stuck on for those renders?

[simmsimaging]

I ran another render when I went to bed. Last test render I did before that, using the preview window, looked fine. The higher res render is badly clamped again - nothing changed in the file. Current setup is in screen cap along with the greyed out result:

[roeland]

The problem here is that the film buffer has only limited precision. Your scene appears to be extremely bright, causing the highlights to be clipped. Either the power of the emitters is too high, or the scene is modeled at the wrong scale.

The default exposure setting is exposure of 1, an F-stop of 2.8 and ISO 100.

--
Roeland

[simmsimaging]

The problem here is that the film buffer has only limited precision. Your scene appears to be extremely bright, causing the highlights to be clipped. Either the power of the emitters is too high, or the scene is modeled at the wrong scale.

The default exposure setting is exposure of 1, an F-stop of 2.8 and ISO 100.

--
Roeland

Ok. I'm not really sure why we have fstop values and ISO that we can't really use though? And why an fstop setting at all when it doesn't control depth of field anyway? Why not just remove fstop and ISO and just use the single exposure value, since it appears to do the same thing anyway?