Awful render times (10 hours and 20% done)

Hi everyone! I’m struggling with my model. Its kitchen scene with a lot of details and has 150MB and 300k edges. I need to render this in 4k but it takes about 2 days to be done… I have tried to cleanup the model but I haven’t seen any changes. Displacement maps, soften edges, delete objects that doesn’t show in render viewport exc… Do I have any choices other than reduce polygons or render in low quality settings? I have MacBook Pro m1 8gb+8gb and I’m using sketchup 2021 and vray 5.10.

Thanks for the replies!

Dropbox link Dropbox - Kitchen scene SU.skp - Simplify your life

I can’t help you a lot because I don’t have Vray - try posting on the Vray forums?

Anyway I took a look at your scene.

Generally - Things that cause massive performance issues for rendering are:

  1. Lots of light sources
  2. Lots of transparent objects; especially objects that light bounces through several times. Each time that light hits a transparent object the renderer needs to calculate every ray of light refracting and bouncing through it.

Your model has both of these issues in combination.

To improve render times:

  • Reduce glass - eg Your windows have multiple panes and you have a lot of glass in the model that’s not even required in the scene, such as back room windows and shower doors. You even have an entire tray of wine glasses on a shelf! Not good!

  • Reduce lighting. You have very large number of lights for such a small room - including omni lights, which shoud be uncessary in a scene like this (because they are not realistic) - and you have windows so you don’t need to arficially boost lighting. Even if your Omnis are very low output they still need to be calculated by the renderer. For windows and small objects you can use "architectural glass’ or “fast glass” (i forget the name in Vray) but it’s single-sided transparent material designed so that it doesnt refract, and is therefore 10x quicker to render.

FYI I spotted a few other modelling issues such as the door frame not meeting the door properly, and a couple of items “floating” on the shelves.
You have a lot of loose geometry (exploded) which means it is difficult for a render to process; usually it would eliminate any objects (Groups/components) that are not “in view” but it can’t do that if they aren’t made in to Groups or Components.

Also, from an architectural design perspective, the height of the top of your windows is less than 1600mm above the floor level, which means that average person will be looking straight into the top of the window frame - I would not recommend that as a design. :slight_smile:

I rendered these images in Indigo (about 16 mins) but this doesn’t use the Vray lights, or your Vray material settings like Bump mapping (those settings probably wont add much time to the render). The image is pretty noisey (grainy) because I boosted the brightness, so I added a “denoised” version.

The export from Sketchup took me about 20 seconds so it’s a fairly simple scene in that respect.


Thank you Sam for the reply and from all the tips & tricks! I’m fairly new to 3D modeling and rendering so that what you said helps me a lot! I will lose all the unnecessary glass and lights! Also use the fast glass and grouping! As a newbie I tend to shop a lot in the 3DWarehouse which is a bit destructive for me :smiley: This is a renovation plan for an existing house where windows are really that low. Again thanks for your time! :slight_smile:

  • Lauri

No problem.
I dont think the 3d warehouse objects are such an issue - renderers don’t really mind if you have 400 polygons, or 400,000 :slight_smile: Complexity in your model will mostly just add time to export it from sketchup to start rendering, it wont affect the renderer much once it has begun.

You may want to watch your Ram usage since the M1 shares video memory with its integrated GPU (??) - so don’t run lots of other programs while rendering.

A good habit with rendering is to render isolated parts of the model; For example I would start with just the room and items within it, and no artificial lighting - just remove the windows and ceiling - then you can review the composition of objects and all the materials (bump map, etc).
Once happy with this, you can start to add lighting, but render the scene using a Clay render mode that eliminates all colour & material and just focuses on the lighting of the space.

These are good methods for trouble shooting what works and what adds processing time.
Interior scenes are always tricky because it takes quite a large number of ray ‘bounces’ (traces) to hit all the objects, so they appear rather dark and grainy.

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Good luck. You’ll likely find ways to improve your time. Proper lighting and exposure may help. Anyway rendering on a Mac is tough. I know, that’s what I do. There should be Vray people to help here, since SketchUp embraced it. Start with some simple models of your own, simple textures and daylight, then work your way up to reflections, IBL, interior scenes etc. Beware of 3d warehouse.

I played with the file for a time, too. Removed all lights that were not attached to a visible luminaire. Couldn’t get any light out of the IES lights so I switched them to V-ray lights. Render times on my PC were just minutes (with RTX rendering)

The model is mostly just loose geometry. Did some of it come from Archicad? (guessing from the tag names).

When testing on RTX 3080, the scene did load very slow and I couldn’t see anything as your IES files and dome light didn’t work.

  1. Reset all render settings;
  2. Turned on Material Override for everything, except glass. Still loaded slow, so issue was with lights, not geometry or materials;
  3. Deleted all lights, except sun and dome. After this render worked very fast
  4. Set Dome light to white color and power to 1000, set sun power to 1 and adjusted the angle to light the scene. Set scene exposure to 7 in Frame buffer
  5. Replaced ceiling color to simple white;
  6. Replaced Floor material, as old one didn’t work with RTX render

Result - 5 minute 4k render at medium quality: