OTOY Forums

bpzen can you post a few ss`s so that we can examine your issue further?

yep will do prob tomorrow afternoon, thanks!

face_off wrote:Reduce GI Clamp - as recommended in the Octane Notes link in my signature below.

Paul

Out of interest, does reducing the GI Clamp to 1 reduce the quality of the image or have an effect on it in any way apart from removing hot pixels?

does reducing the GI Clamp to 1 reduce the quality of the image or have an effect on it in any way apart from removing hot pixels?

Yes, it makes it "less un-biased". At exposure 1, a GI Clamp of 10 seems to be close to the same quality of 100000. But a GI Clamp of 1 to me, with some scenes, seems "less real".

Paul

How does this work with spot lighting where the scene is lit in a few places to create a noir look? Is it correct in OcDS scenes to light the scene brightly all over and then light specific areas even brighter with spots and then lower the ISO to darken the scene down?

You got it!
That's exactly how you do it. This way, there is lighting information present in every place of your scene, which makes it easier for the renderer to pick up texture and shader information.

Edit: Speaking of noir - I applied the exact same technique a while ago in the render attached.

That's a great render and exactly the effect I'm after. It does seem counter-intuitive to over light a scene but if it prevents the dreaded hot pixel problem then job done.

Ok, this hot pixel problem is still occurring. I'm using an HDR environment. A 20 meter plane set to texture emission lights the whole scene from above. I have another 0.5 meter plane set to black body with an Octane IES spot lighting the figure. No matter what level I increase the texture emission and lower the exposure I still get hot pixels from the spot even when that level is set higher than the texture emissive surface. Are there any diagrams about how to set up a scene using HDR and emissive surfaces that might shed some light (pun intended) on this problem. I'm really not getting it and at the moment so it's pot luck whether the lighting works or not. I'd much prefer it if I understood the technical issues so I could create controlled lighting.

Ok, this hot pixel problem is still occurring. I'm using an HDR environment. A 20 meter plane set to texture emission lights the whole scene from above. I have another 0.5 meter plane set to black body with an Octane IES spot lighting the figure. No matter what level I increase the texture emission and lower the exposure I still get hot pixels from the spot even when that level is set higher than the texture emissive surface. Are there any diagrams about how to set up a scene using HDR and emissive surfaces that might shed some light (pun intended) on this problem. I'm really not getting it and at the moment so it's pot luck whether the lighting works or not. I'd much prefer it if I understood the technical issues so I could create controlled lighting.

It would help if you posted a screen shot of your viewport showing the hot pixels, and a screenshot of your render and environment settings.

Paul

face_off wrote:

Ok, this hot pixel problem is still occurring. I'm using an HDR environment. A 20 meter plane set to texture emission lights the whole scene from above. I have another 0.5 meter plane set to black body with an Octane IES spot lighting the figure. No matter what level I increase the texture emission and lower the exposure I still get hot pixels from the spot even when that level is set higher than the texture emissive surface. Are there any diagrams about how to set up a scene using HDR and emissive surfaces that might shed some light (pun intended) on this problem. I'm really not getting it and at the moment so it's pot luck whether the lighting works or not. I'd much prefer it if I understood the technical issues so I could create controlled lighting.

It would help if you posted a screen shot of your viewport showing the hot pixels, and a screenshot of your render and environment settings.

Paul

I went back to the scene, deleted the large plane and increased the sampling rate of the spot - adjusting the power, gamma and exposure of the spot, HDR & overall render to achieve the look I wanted. It seems to be a matter of fine tuning everything so perhaps there isn't one specific, foolproof way of doing things because it all depends on the lighting and the scene. Adjusting the sampling rate seemed to clear up most of the granular appearance and hot pixels coming from the spot.

Granularity in dark areas is a different issue (again, see the Octane Notes in my signature). But without a sample of what is happening, it's almost impossible to provide meaningful assistance.

Paul