Unusually slow render
lasersayspew
Posts: 71
Hello! So, here's the problem:
I'm making a house interior. Got several rooms in different scenes each cause my potato computer can't handle them all in 1. All rooms render in 30 mins to acceptable(for me at this point) quality in HD. But there is one slowpoke room that I rendered for 1 hour and it still looks like crap. Its a corridor: only walls, doors and a ladder. 3 light sources. The pic's attached. Other rooms got sofas, mirrors, showers, kitchen stuff etc. and they render in 30 mins. Not cropped, some fireflies perhaps. But this one...I have no idea what is wrong. The only thing that is different for this room is that I once grouped everything in the scene and rotated it 180 degrees and then ungrouped. To allign it with other rooms.
Could that be the cause? What else should I check?
Also quick question: is hiding an object the same as deleting it in terms of render speed? Because while writing this I realized that this particular scene also contains outside stuff like ground(plane with grass texture, no real grass obviously, remember, potato), fence around the whole house. But all this stuff is hidden.
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Comments
It probably has not enough light rays to work with. It looks rather dark. Try adding in more lights. You can try ghost lights, point lights or use this camera with the sun-sky or a hdri https://www.deviantart.com/heroineadventures/art/Iray-interior-camera-for-DAZ3D-Version-1-1-728244344
This one looks even darker, yet it's not as grainy as the one in the first post. And it took 30min vs 1hour.
You can put some probe type lights in the corner where you have problems. Anything not visible in the scene will not affect your render, it is not rendered if unseen.
The whole room is a big problem xD Floor is grainy, back wall is extra grainy. If the problem is in absence of enough lighting then I don't understand why is the second attachment, that is even darker, took half the time and has no grains at all? Not that I can see at the very least on the illuminated areas.
I can't really tell what is going on from those images, but grain that iss low to converge tends to mean either a) each light path is taking ages to resolve (e.g. from very glossy surfaces) or b) there are areas which receive only bounce light, so it takes lnger for the light to get in there. Level of illumination isn't the issue per se, it's how hard some or all of the surfaces are to resolve. Adding fill-lights, and adjusting the one-mapping to still get the look you want, is probably the answer here.
Your light sources are mesh lights? spot lights? Also, are all the rooms from the same set?
If they are mesh lights, and they have multiple ploygons that emeitt light, each polygone adds to the render time. It'd increase the lumiance value of your mesh lights first and see if that sppeds up render times.
Also, your second image had apparently hdri light from the outside. You first one should be set to "scene only", unless it has a window in it or something that allows light into the room. Otherwise, the external light source is adding to the render time, even though it's not actually contributing any light.
Maybe you run out of VRAM on your graphics card then and it renders more on the CPU? Which GPU do you have?
You can try deleting things that are not necessary and see if that helps reducing the memory.
If you hit render there pops up a window and in it on top there should be lines like this. If the memory consumption is higher than your VRAM of your GPU, the CPU takes over and it takes ages.
2018-08-04 13:32:07.283 Iray VERBOSE - module:category(IRAY:RENDER): 1.2 IRAY rend stat : Texture memory consumption: 1024 B (device 0)
2018-08-04 13:32:07.284 Iray VERBOSE - module:category(IRAY:RENDER): 1.2 IRAY rend stat : Geometry memory consumption: 0 B (device 0), 0 B (host)
2018-08-04 13:32:07.287 Iray VERBOSE - module:category(IRAY:RENDER): 1.2 IRAY rend stat : Lights memory consumption: 196 B (device 0)
2018-08-04 13:32:07.288 Iray VERBOSE - module:category(IRAY:RENDER): 1.2 IRAY rend stat : Material measurement memory consumption: 0 B (GPU)
2018-08-04 13:32:07.288 Iray VERBOSE - module:category(IRAY:RENDER): 1.2 IRAY rend stat : Materials memory consumption: 9.80469 KiB (GPU)
If you want a dark room and there are few reflective surfaces it is often better to render with good light and then darken the image in post using either Gimp or Photoshop and adjust the exposure. Iray renders longer in dark scenes, you could use tone mapping to bring the light down in the scenes render while still having adequate scene lighting to render quicker without fireflies.
You could create a pane and make it emissive raise it to the ceiling above the camera's view and increase the luminance to improve the light in the room then fix the exposure in post.
Both pics were rendered in scene only, using only CPU, my GPU is slower. All light sources are ghost lights. I've been learning Daz, CG, lighting, pretty much everything from scratch for less than 2 weeks in a kinda slow pace, are mesh lights the same as ghost lights? Not sure about polygons, how do I check that?
Rooms are made with some sort of constructor, building them myself so I guess yeah, they are from set.
The same room with lights on. The light source is in the picture, will your way work in that situation? The dark room is actually not a problem, it's the other one. It has dark and light versions too and both are grainy while giving it double time to render.
Okay, thank you.
Yes, mesh lights are basically ghost lights, though ghost lights are always hidden by transparency.
If you made mesh/ghost lights, did you create them yourself or used the Ghostlight set from the store?
If you create them yourself, make sure that in "options" you have just one division. That will create just one polygon.
I used ghostlight set, I don't know how many polygons are there. But I use the same set in all rooms, why are the results so damn different in rendering times. The corridor has 1 more light than the room with the sofa. There is actually a light right in front of the back wall that is going down from the ceiling. The outside light that comes through windows is a ghost light too, a dome shaped one right outside of the window. And it's the same for both pictures, I saved it as a subset and copied it from one to another.
Ghost light set has low poly, they are mostly planes (I have this). You could turn up the emissive property on them to improve the lighting, this would improve the render.
Found the problem! xD Thank you for your help and advices! And I will try that hdri camera preset, thx!
And if you're curious the problem actually was in HDRI even though I had Scene Only render. The thing is while trying and learning HDRIs I actually never got them to work properly, no shadows on the ground no matter what HDRI and settings, tips and advices I tried from other threads. The only HDRI that dropped shadows was Pixar's one. So I googled again and again and finally found some sort of dome with ground that is actually part of the scene! And it worked, shadows appeared! And I had that thing in the corridor scene. Even though I turned it off(it has a group that consists of dome and ground), the group was hidden while the contents weren't for some reason. xD Just did a 3min render with ON and OFF on that one and the difference is huge. Attached those 3 min renders.
Again thanks for your help guys! Love the community!
Excellent