How to shorten long render times

aaráribel caađo

I've been using some simple 3- and 4-spotlight set-ups for scenes with few items in them and experiencing hour-plus render times. Once the resources are thrown over to 3Delight and the rendering starts, it moves briskly until the 70-80% (by the rendering dialogue's estimate), then gets progressively slow. So the first 10% happens in a minute or two, but the last 10% can take 10-20 times as long.

Since I'm not using any processor-intensive lighting techniques, beyond soft shadows, I'm baffled. I'm moderately experiences with 3D basics and lighting (but from a 5-year old Maya and Modo perspective), but I don't have a solid grasp on the intricacies of the 3Delight render settings (which I set to "4" and leave alone). I'd love some suggestions for optimizing my renders so I'm not wasting processor cycles on things that aren't appearing in the final image.

The attached image took over an hour to render. There is a lot of hidden geometry, but nothing exposed to the camera.

(Side note: why are all the female figures so tall? They're all in the 95-99th percentile of height)

Richard Haseltine

I can't say I've ever noticed a slow down if the workload is evenly distributed. However, with soft shadows and transparency (on the hair) it's possible that some of those buckets are getting stuck, so they are still being rendered while the rest of the image has finished. SSS calculations can also slow things down.

Although the DAZ females are generally unusually tall they aren't that tall - I suspect you are using a scale made for Poser, using the de jure 1 OBJ unit = 8.6 feet scale, instead of one made using the DAZ Studio (and the widely used de facto standard for Poser) scale of 1 OBJ unit = 8 feet.

Medron Pryde

When I went from no light to light, my render times went from around 10 minutes to an hour or so. It takes a long time to figure out all the light angles.

But in the last couple days Daz Studio has gone from the hour or two for really detailed stuff to five or eight hours for the same scenes. That's just...way too far out there and I have no idea what happened....

aaráribel caađo

Hi Richard,

I just timed out a render that didn't have hair, but a lot of SSS. No shadows, DOF, etc, nor any image maps on the skin (just one the eyes and clothes). Here are the times

50% rendered = 19 seconds
70% rendered = 42 seconds
Finished = 3 min 20+ seconds (I didn't see the exact seconds count before it finished, so this isn't precise)

That feels typical for my renders, regardless of hair (or SSS—I think the skin settings I've used don't have SSS active).

The render looks done by the 70% mark, so iI'm not sure what's being calculated at that point. It might be render overkill on my part, or it might be something I don't notice in the render window.

————————

I wondered why that prop was off. I know the height for the G2F is something like 5'10" (still 95th percentile height!). The poser v DAZ scale explains that. Thanks

jestmart

Do you have progressive rendering checked?

aaráribel caađo

OMG! Wow, that instantly improved things. Not only did it make the render times percentage linear, but it radically shorted my render time. Thanks!

Medron Pryde

I have no idea what changed over the weekend.

I've been doing print quality renders for a while now. 8,000 to 5,000 pixel renders so they are big.

Without lights, they took me about 10 or 15 minutes to render.
I'm learning DAZ at this time, and when I discovered lights I about jumped with joy. It took an hour (two hours for complex scenes) but the quality was out of this world. And I could do this while playing games like Guild Wars and Guild Wars 2 DURING the render process.

quad core 3.4 ghz computer with 12 gigs ram. I have power to burn. ;)

Then over the weekend, render times went up to 8 hours, or more. And I couldn't do anything while it rendered...even surfing the web hit thirty second long freeze times and other crap. It was horrible. It was using 100 percent of my cpu cycles...that's not right.

As a test today, I loaded up a file I rendered last week in about an hour. Today I started it up and went to bed. I woke up and checked the render 8.5 hours later and it was 16% done. I canceled the render because that's just BS. I single character with standard character light rig and no background has no business taking that kind of time.

So I looked for the "progressive render" button and found it. Set it. Redid the same render. I went to watch The Voice and when I checked it was done. I checked the date stamp and it looks like it was done in less than 45 minutes. I don't know exactly though since I wasn't watching it.

I tested another render and it was also done in less that 45 minutes...closer to 35 I think, but once again that is an approximation. The good news. I can once again do other stuff while the render is going on in the background.

I have no idea what happened to DAZ to make it go crazy long render times and I made no setting changes, but the progressive render button appears to be a magic "speed this the heck up" button as far as I can see.

Do any of you have any clue what could have caused those crazy long render tiems?

Richard Haseltine

Progressive render can be faster - a lot faster - with complex lights. It can also be slower with more simple scenes. I can only think that you had had progressive on and you loaded a scene or preset that overrode that, setting it to off, causing the slow down you saw.

Medron Pryde

That sounds reasonable. Sounds like I'm going to have to check the progressive button before I hit render from now on....

jpb06t

Richard Haseltine said:

Progressive render can be faster - a lot faster - with complex lights. It can also be slower with more simple scenes. I can only think that you had had progressive on and you loaded a scene or preset that overrode that, setting it to off, causing the slow down you saw.

I did a few experiments and the render times for the progressive setting were so tragically long that I stopped using it.

I wonder how a progressive render could be faster than a normal one; on every application I used since my first attempts with POV-Ray in 1997 progressive has always ment fast to get some idea of what is happening but overall (much) slower than the real thing .

Richard Haseltine

Progressive is actually a different renderer, in part, from the regular renderer. I'd given up on it as too slow for anything but crude previews, until I was struggling with a complex light set (one of Predatron's I think) when I was told to try it and it was vastly quicker - I'd cancelled the standard render after a couple of hours, progressive was complete in about twenty minutes.