Sketchup/Twilight Render


#1

Fairly new to this - when I render my SU model I get weird ‘stormy clouds’ on my walls. I checked front/back using monochrome everything looks good. What am I missing? Used the lowest preliminary render setting


#2

Looks like the only light is coming through the doorway on the right. I expect you need more.


#3

There are windows on the left wall in the back and I can adjust the render settings (didn’t for this one). Still shows the funky black/white splotches on the wall.


#4

I think it’s a combination of lighting and the fact you have it on very low settings. Have you tired leaving one on for a while to see if it improves?

I used to have a similar issue (at least visually) using Podium years ago.


#5

Umm…Leave one what on? (sorry…again newbie here!)


#6

The render, increase the quality and let it run for a longer amount of time, you may find that a lot of those dark splotchy areas improve.


#7

Ran for 35 minutes (time to go home now!) on 5+ but still have the weird splotches. (thanks for your help)


#8

You would need to post your full computer specs, file size, render resolution in order to see how long it should take.

In comparison without GPU support I can run a render for between for over 100 hours per single frame. With GPU support this time is 11-12 hours per frame (including lights, reflections etc), so it’s possible it just needs to go for quite some time longer, a couple of hours at least.

Another idea it to remove the roof from the model and render again, you can then at least eliminate the fact it’s a lighting issue and not a material issue depending on the result.


#9

Pay attention to how the material looks when editing it. If it looks grainy, then it might come out grainy.


This might be because your shininess isn’t high enough.


All renders where done on “low+”.
I’m still trying to figure this out, but I hope this helps.


#10

Hi there
your splotches on the walls will be down to the number of light samples and the fact that all your light is coming from an single opening - the light(rays / samples) will need a significant number of bounces from from the camera back to resolve the position of the light.
I haven’t used twilight but they all tend to be similar - in Vray you would add an invisible portal light in the opening or Maxwell an area light the shape of the opening set to invisible with a high lumen / wattage value to roughly match the sun power, this will provide your scene with vastly more sample / rays for the renderer to work with and help resolve those splotches. in addition scenes are rarely lit with a single light, so think like a photographer and try a subtle fill light behind the camera (you can turn off shadows for that light), again this provides light ‘resolution’ for the rederer to work with and you might actually find your render time comes down.
hope this helps, as I said I haven’t used twilight so I might be talking rubbish and there is ‘remove splotches’ checkbox in twilight - if so click that :slight_smile:


#11

No experience of Twilight but I have seen similar splotches with other renderers when using materials with no textures attached or when the textures have been very small.


#12

Thanks everyone! It was the lighting - added more and no more splotches! (though I was kinda hoping it was going to be the ‘remove splotches’ checkbox! LOL!)


#13

I’ve found it’s often useful to think of issues like this in terms of real photography. Your image made me think of an underexposed image printed to try to eke out any and all detail possible.


#14

I recently watched a youtube presentation on that very subject I thought was very helpful. You probably are familiar. https://www.youtube.com/watch?v=yYZuVpddCgk


#15

Thanks for the link to that video. It’s one I hadn’t seen before but very interesting.

I spent enough years doing photography professionally and teaching it to others that when I started monkeying with rendering my SketchUp models, I just automatically thought about it from a photographer’s view. I didn’t really think it was a thing, though.


#16

Yes, and if you really want to master photographic lighting, Light, Science and Magic is a fabulous book for theory and practice.


#17

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