Render Quality bad

sidneychuffnuts_30c47d3a3b

Hi everyone, having real issues with iray rendering a scene, am using hdri skydome - white/grey areas look as though not rendered in patches in the scene and fireflies in darker shadows - have been having this trouble since the update. Have I missed something or am I doing something wrong?

Am pulling my hair out as whatever I do doesn't seem to make it better. It's almost as if it hasn't finished rendering?

Thanks for any input

TheKD

There are three triggers that tell iray it's "finished". The time slider, the max samples sliders and the quality slider. One of those things is triggering the render to stop. The way I like to do it, is turn the max time to 0, this turns off the time trigger. Also turn off render quality enable, this turns off the convergance trigger. Then I add a few zeros to max samples, you have to click on the gear icon in that box in the far right side, also max out the min samples slider. Then just have to cancel the render when it looks good enough.

sidneychuffnuts_30c47d3a3b

Thanks TheKD

Am just doing another as we speak, settings are:

Longest edge set to 3000 pixels - then I can just increase in Photoshop

Auto headlamp is off

Minimum Samples is maxed

Time is set to 7200

Render quality On with a value of 10

On the advanced tab I have everything ticked as I have Nvidia 1080 (not sure if this really matters)

At the moment it looks as though it is a bit better - will leave it to finished and then try your suggestion

Have seen another thread that states it may be something to do with materials and bring the specularity value down - but I still have problems in the darker areas

Thanks for your help

sidneychuffnuts_30c47d3a3b

UPDATE:

It looks as though it's getting worse as the render is going along - what appeared to be a bit better is now exactly the same as before - am going to cancel and try your suggestion

sidneychuffnuts_30c47d3a3b

Have just started your suggestion for render settings and it is exactly the same, starts off ok then starts adding white bits - still getting fireflies in darker areas. Am going to leave it rendering to see if it gets better, but it appears to be getting worse as the render goes on.

zmk

You're correct, it hasn't finished rendering. The noise means that not enough samples have been processed in the specific areas the camera rays are hitting.

You could try adding some soft, weak lighting onto the dark areas to help the process and see if it helps in this specific scenario. Dark areas naturally need a lot more samples to become less noisy.

sidneychuffnuts_30c47d3a3b

Thanks zmk

In the light areas it appears to be adding white in as it goes along - and the longer the render the worse it gets. I will try adding soft light to the dark areas to see if that helps - my settings:

Min update Samples =1 - Update Interval = 5.00 - Min samples = 100 - max samples = 15000 - max time = 0 - Render Quality Enable = off - Rander quality = 30 and Rendering Converged Ratio is set to 95%

Thanks for your help

Richard Haseltine

If you are getting increasing white points it's possible that a surface is too shiny and what you are seeeing is refelctions of the light sources. Adjusting the surface to be less shiny may help.

Olo_Ordinaire

sidneychuffnuts_30c47d3a3b said:

Thanks TheKD

Am just doing another as we speak, settings are:

Longest edge set to 3000 pixels - then I can just increase in Photoshop

Auto headlamp is off

Minimum Samples is maxed

Time is set to 7200

Render quality On with a value of 10

On the advanced tab I have everything ticked as I have Nvidia 1080 (not sure if this really matters)

At the moment it looks as though it is a bit better - will leave it to finished and then try your suggestion

Have seen another thread that states it may be something to do with materials and bring the specularity value down - but I still have problems in the darker areas

Thanks for your help

I would suggest looking at the Tone Mapping and Filtering pages on the Render Settings pane.   Your render times will go up considerably with Render Quality set to 10.  I would dial that back to 1 until you get a handle on basic render quality.

Under Filtering, make sure to turn on the Firefly filter!  It does a great job of eliminating sparklies in dark areas without damaging image sharpness and detail.

Set the scene brightness and contrast  using the Tone Mapping page under Render Settings.  I turn on Iray preview in the viewport and then adjust the Exposure until the image looks properly lit, then I tweak Burn Highlights, Crush Blacks and Saturation according to the image "feel" that I want.   Burn Highlights eliminates highlight detail, the higher it is set -- this can be good for high-contrast images.  Similarly, Crush Blacks eliminates shadow detail, and can be used to create a moody, "film noir" effect.  Saturation affects richness of color, of course.

Under Progressive Rendering, I set Max Samples to 10,000 and leave Min Samples alone.  You can set Converged Ratio to a larger number for higher quality.  For my "important" renders, I set this to 99%.

Good luck!

 

fastbike1

Render quality 30 is way too high. That's not your problem. Proper lighting with render quality 1 will give great results.

Attached all with render quality 1

 

sidneychuffnuts_30c47d3a3b

Thanks everyone for your input - am trying your suggestions and looking good so far, have dropped quality down adjusted tone mapping, firefly filter was already on. Have changed maximum samples, and have been playing around with the tone mapping. Still can't get the quality that fastbike1 gets - not sharp, very grainy. Will post result when done later today. Shadow areas very grainy.

Thanks all for your help with this

sidneychuffnuts_30c47d3a3b

UPDATE: Looked at the materials and turned down all the glossy attributes to zero, have done all your suggestions and it's working a treat so far - the render is taking a lot longer though - it's been 2 hours so far and guess it will probably take around 8 hours in total - is there any way to speed this up without losing quality?????

So the problem seemed to stem from various parts - glossy material and too much light in the light areas - it must have caused some kind of bloom or artifacts - in the darker areas I have darkened it up a bit which seems to have helped with the fireflies will post a section of the final render for your to see when its finished.

Thanks everyone - this community is awesome

AbnerK

sidneychuffnuts_30c47d3a3b said:

UPDATE: Looked at the materials and turned down all the glossy attributes to zero, have done all your suggestions and it's working a treat so far - the render is taking a lot longer though - it's been 2 hours so far and guess it will probably take around 8 hours in total - is there any way to speed this up without losing quality?????

So the problem seemed to stem from various parts - glossy material and too much light in the light areas - it must have caused some kind of bloom or artifacts - in the darker areas I have darkened it up a bit which seems to have helped with the fireflies will post a section of the final render for your to see when its finished.

Thanks everyone - this community is awesome

As someone else said. Good lighting makes a HUGE difference. If you are familiar with real cameras then you'll know you can get very grainy photos if you set things up badly, ie, not enough light and too wide an aperture. I think Kodak have a great little demo on their site about noise. Also I would recommend you good the forum for rendering. There are so many threads. You'd be doing yourself a favour by reading some of them. You'll learn from your mistakes. I'm still learning after 2 years. I feel I've hardly scratched the surface. :)

sidneychuffnuts_30c47d3a3b

UPDATE: All your help has worked wonders, left it to render overnight - no problems which I had before - thanks jimmac-donald for your thoughts I will be reading through the forums and the Kodak site. Strange that I never had any problems before the latest update, but probably just a coincidence. Thanks for all your help.

fastbike1

@sidneychuffnuts_30c47d3a3b "is there any way to speed this up without losing quality"

There are a couple of things you can do without significantly compromising your image. I don't know how you light your images ot whether you have used Studio or Poser in previous incarnations.

1. the first thing with lighting is to minimize or eliminate "mesh" / emissive lighting. Ther is a lot of outdated information and recommendations to not use spotlights and go with mesh lights, but Iray has eliminated the harsh shadow issues with spotlights. Mesh lights with anything but the simplest geometry (minimal polys) take longer to render. Iray spotlights render much faster and have a geometry attribute. Geomoetry lets us emulate a photo graphic softbox of virtually any size and several shapes. As with real world photography, light sources that are close and large result in softer shadows.

2. Simpler scenes. Multiple figures and complex props will eat up a lot of VRAM, run the risk of defaulting to CPU, and take longer to resolve shadows and reflections.

3. CLose-ups (i.e. character head or head and shoudlers) take longer to render. Hair in particular can greatly increase render time in close shots.

4. Be careful about high subD settings. Many products are starting to have higher subD settigns than might be warranted for the scene. Higher subD give more detail, but often won't be noticied in the scene.

5. Hide geometry that won't be seen. Feet in some shoes and boots are an example. parts of figure when clothed are another. Bear in mind that invisible objects will still throw shadows or reflections in Iray.

3. Sadly, the dominant way to speed up renders is to get a better Nvidia GPU. GPU rendering "capability" is dominated by VRAM. Rendering speed is dominated by the number of CUDA cores in the GPU. Later GPUs tend to have faster architecture than earlier one, although the magnitude of increase is difficult to specify. Short advice: buy the most CUDA cores, VRAM, and latest GPU you can afford. My personal priorities are CUDA cores over VRAM since I don't render large scene with many figures.

4. Use GPU-Z to monitor your GPU duriing renders. This will give you a better idea of how much VRAM is being used.

5. The various Iray versions in Studio have minimum driver requirements. The latest Nvidia drivers should generally be viewed with suspicion and not downloaded unless you have a specific reason (personal experience). If you run Win10, updates may overwrite you GPU driver with a substandard Microsoft driver.