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reflective surface causing specs

Posted: Mon Aug 10, 2015 2:20 am
by bpzen
hey all,

ive seen this before and normally increasing caustic blur, decreasing direct light importance and setting remove hot pixel to 1 or 0 seems to solve. but not i cant seem to get rid of these hot pixels all over my figure . I am using mesh lights only 4 spheres and have done a few renders and they look good but now for some reason i am getting these speckles all over my figure and i believe its due to a shiny object on the floor and he is bent over now sorta in that direction.

is there anything else i can try?

in door lighting with no sun or no HDRI is suck a B@#$@# with this engine , stand alone , poser plug in or daz plug in ...........

Re: reflective surface causing specs

Posted: Mon Aug 10, 2015 9:27 am
by bepeg4d
Hi,
it would be nice to see an image for better evaluate, but, in general, firstly check your bump and normal values, if they are too high, it's easy to get fireflies
Are you using IES files for the emitters?
Anyway, the faster way for killing all the fireflies is to render at double size with a quarter of sampling and then downscale the final render to the original resolution. In this way all the 1 bright pixels should be removed avoiding to use the Hot Pixel Removal that kills all the details ;)
ciao beppe

Re: reflective surface causing specs

Posted: Mon Aug 10, 2015 10:07 am
by TRRazor
Anyway, the faster way for killing all the fireflies is to render at double size with a quarter of sampling and then downscale the final render to the original resolution. In this way all the 1 bright pixels should be removed avoiding to use the Hot Pixel Removal that kills all the details
Rendering at double the resolution will add the time to your workflow, otherwise spent on removing the fireflies in PS or whatever image processing sofware, so that's not a valid option imho,
Too many fireflies usually indicate a wrong lighting approach with light sources being overpowered.

Try lowering the "Power" settings of your light sources and try to compensate by lowering your Exposure value in the Render settings.

Furthermore - when indoors - try using Portals, as these will channel the lighting from outside into your indoor areas.

PS: Specular materials will always take the longest time to clear up. If it only affects a certain part in your image, leave everything rendering with Hotpixal removal at the standard value.
Then - when satisfied with the rest of the image - save it.
Afterwards set the hotpixal removal to a lower value (so more hotpixels are being removed) and leave it rendering for a second - now save again under a different filename,
Now blend the removed hotpixel area with the detailled one image in PS or another image processing software.

Re: reflective surface causing specs

Posted: Mon Aug 10, 2015 1:17 pm
by bepeg4d
hi TRRazor,
seems that you have skipped the second part:
…at a quarter of sampling…
this gives roughly the exact render time than rendering at the original resolution and sampling.
A simple example:
Original size and sampling: 1024x512px @1024 sl.
Fireflies-free version : 2048x1024px @256 sl.
Downscale to the original dimensions in reducing mode in your prefered image processing app.
As I already said, this is the faster way for having fireflies-free images in one go and it's easy to automate.
Also your method is not bad, but you have to render twice the scene with different settings, combine the layers and so on.
ciao beppe

Re: reflective surface causing specs

Posted: Mon Aug 10, 2015 1:37 pm
by bpzen
Great info,

I will try and get a sample image to show you today, im wondering if i am using the wrong term for the issue im having.

The setting is a room with out windows, so opening up a window is not an option and hiding a wall takes away form the mood i was going for dark scary room.

Th eissue i am having may be not enough light. The figure I have is bent over and his chest area has no direct light on it, it looks fuzzy and grainy, I tried to move the lights to see if a diff direction will help ill let you know and or post a sample in a bit.

PS

Hot Pixal removal should be set to 1? I had no idea it removed detail.... :(

Re: reflective surface causing specs

Posted: Mon Aug 10, 2015 3:22 pm
by TRRazor
seems that you have skipped the second part:
…at a quarter of sampling…
this gives roughly the exact render time than rendering at the original resolution and sampling.
Nope - didn't skip it, but simply try to solve the actual problem, instead of leaving users with a wrong approach in their workflow and trying to find a cure for the cause, instead for the symptoms, like the one you suggested.
Also your method is not bad, but you have to render twice the scene with different settings, combine the layers and so on.
No - that doesn't mean you have to render the image twice - seems like you skipped the second part there ;) - read again:
Specular materials will always take the longest time to clear up. If it only affects a certain part in your image, leave everything rendering with Hotpixal removal at the standard value.
Then - when satisfied with the rest of the image - save it.
Afterwards set the hotpixal removal to a lower value (so more hotpixels are being removed) and leave it rendering for a second - now save again under a different filename,
Now blend the removed hotpixel area with the detailled one image in PS or another image processing software.
All of this can be done in one and the same render session (simply leave the OctaneRender viewport up, save, change hotpixel value, leave rendering for one second - save again. That simple :)

Re: reflective surface causing specs

Posted: Mon Aug 10, 2015 5:09 pm
by bpzen
so i think i figured it out

I had 3 small spheres 2 on each side inside Halogen floor flood type lights, the glass encasement of this even at opacity .1 and all he other settings causes all sorts of issues, hot pixels, grainy spots etc... bad render. I moved the mesh lights out of the glass sorta in-front of it and cleaned up. I had seen glass cause bad rendering with Octane stand alone and Poser plug in, seems it dose not handle that too well.

thanks for all the responses learned some stuff :)

Re: reflective surface causing specs

Posted: Mon Aug 10, 2015 5:26 pm
by bepeg4d
hi bpzen,
I'm glad to hear that you have solved, but unfortunately, here in the DAZ section it's quite difficult to have questions with screenshots and images that properly explain the issues, so it is not easy to spot on immediately what's going on.
Probably my answer was not the best, but surely I wasn't a wrong information.
Sorry to have thinked only to the symptoms and not to cure.
Fortunately there are very good doctors here ;)
ciao beppe

Re: reflective surface causing specs

Posted: Mon Aug 10, 2015 6:07 pm
by TRRazor
No hard feelings mate - you're doing a great job supporting the folks here on the DAZ boards - keep up the great work :)

Re: reflective surface causing specs

Posted: Tue Aug 11, 2015 5:24 pm
by bpzen
thanks to all no matter the suggestions, i learn form the replies even if i try and it dont fix ;) everyone here is very supportive an d quick with ideas !

I just wish I never got Poser to begin with 2+ years back DAZ fo r me is so much better workflow and has more to offer with othe r 3d apps. And has MUCH less lag in loading and posing etc...