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Posts: 14
Reply with quote  #1 

Hey guys,

I'm after some advice to speed up my render times. This scene: Cliff over hang 2017-07-11 16125900000.png 

took 2 days and 12 hrs to render on 'exterior high preset'. I'd like to speed this up by quite a large margin - if that is possible!

Should I only be modelling what I want to be in the shot - in this model I've modelled quite a bit to get several shots, maybe producing several different models for each shot is a better option?
How much detail do you actually put in to your models, for example: would you model a double glazed window with the 2 panes, air gap, sealant and framework? Or just face that would be in the shot?
Any advice in the modelling stage would be much appreciated - i've also attached the sketchup summary for your info.

Below are also specs of my computer - maybe there is something I can upgrade to help performance?

Mac Pro 2008
Processor: 2x3.2GHz Quad-core Intel Xeon
Memory: 16GB
Graphics NVIDIA GeForce 8800 GT 512MB


Many thanks for your input and advice

Attached Files
pdf The Pit Sketchup Summary.pdf (79.47 KB, 6 views)


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Posts: 10,513
Reply with quote  #2 
This is a similar specification to the Mac Pro I use for my day job.

I find it's normally very fast.

There are 3 really notable things you have done which will significantly increase render time on their own. All together they explain entirely why you have such a slow render [smile]

1. You have a 3d tree in your scene. That will increase your render time by a few minutes. Until instancing is implemented, multiple 3d trees will hit render time quite hard.

2. You have rendered using the exterior high preset. Do not use the high presets unless the output from the default ones is not good enough. I can't stress this enough. The high presets are significantly slower, but higher quality. No-one should simply use a higher quality preset automatically thinking they will benefit from it. In many cases, you might not be able to tell the difference. The exterior high preset is for when you have delicate detail in an exterior, and you can see the shadows cast quite clearly, close up. For example delicate metal furniture on a pale paved surface in the foreground of a scene.The difference it makes is much softer and more detailed shadows. Indirect illumination will be more even and higher quality. Have a look here and here.

3. You have rendered a high resolution image. Resolution is one of the most important determinants of render speed. Bear in mind that when you double your render size, you quadruple the number of pixels, and render time. 

You have combined all these 3 things in the same image! Rendering 3d trees with a high preset is absolutely mental [smile]

Address these things and your render time should be much, much faster!

In terms of detail, you need to add just enough to make your scene convincing. You don't render multiple thickness of glass in double glazed units unless you are trying to show something specific about the glazing.

You wouldn't normally render the seams of zinc roofing or cladding. Most of the time you would use a texture.

You would model the thickness of a casement, the copings on brick walls, or divide up your walls so that you can texture the brick copings so that they look right. You would position your textures so that for example you don't get impossible little brick slivers in places like over the timber lining for the window on the left.

You would model the metal flashings over the top of the brickwork, and you would model the joints between the frameless glass balustrade sections. You would make sure that you get the construction detail at the base of the balustrade units high, and you would model that with little gaps between the glass and the fixing gaskets. 

You should also add a little irregularity to the ground. I use Julia Eneroth's Erode plugin for this, with very low settings. You would need to subdivide the ground plane quite a lot, and smooth it after it has been distorted.

There are all sorts of other little details in the scene that stop it looking realistic. The glass settings are either not good or you have done something odd with the modelling. That little balcony for example is too narrow even to clean the glass [smile]

There isn't enough attention to detail with a number of things. The columns are too shiny, the timber edging to the window is way too narrow, the edge to the walkway looks wrong and that ramp is way too steep. Details like this do matter. They make the difference between good renders and great renders.

Some of your textures aren't right. That timber texture for example isn't good in that context.

Start simpler, get your basic model and textures right and looking good, then use things like 3d trees.


That which does not kill us makes us stronger
-Friedrich Nietzsche


Posts: 14
Reply with quote  #3 


Thank you very much for you reply and tips. I will certainly address the areas you mentioned to speed up times and produce a better detailed, quality image. I have a few more questions:

The default preset usually comes out with a speckled effect on shiny/reflective materials, is this common or are there further settings I should adjust to omit the effect? This doesn't appear on the high preset, one reason I chose that setting.

In regards to the textures, I download direct from the browser and never adjust the render settings, as they normally come out looking good. is this generally the case? I can only assume the glass has come out looking how it is because I did model it as a double glazed unit....I'll remodel as per your suggestion and compare the result. The window to the left is infact a set of frameless bi-fold doors, so would fully open up the area onto the mini balcony, making plenty of room for the cleaning [smile] I think in hindsight i need to increase the frames at the top and bottom of the doors though.

The edge detail to the walk way - would you not have some sort of coping/drip detail, this what I modelled but maybe it needs to be more substantial?

Can you clarify what you mean by the timber texture not looking good in this context and which ramp you mean?

The Erode plugin, is this not the same as the sandbox tools already in sketchup or do you feel this plugin is better?

Many thanks again for your time and helpful comments!


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Posts: 10,513
Reply with quote  #4 
There is the default preset, and the exterior default preset. Generally they work fine. I've rarely had problems, but when I have had them, they have been on very simple scenes. The more detail in them, the better they render - up to a point of course!

There is no point modelling your glass as double-glazed units unless you are going to see the thickness of these panes up close and in section.

Unfortunately all your detailing is pretty suspect actually. From the linings in the windows, to the short length of timber wall, to the steel columns coming onto the brickwork, lack of copings on the external wall, to the width of the standing seam panels (normally 450-600mm) to the detailing on the bottom of the glass balustrade, to the width of the glazing/curtain walling members.

The variable width timber detail makes no sense for such a short length or for the soffits, used on an external wall, there would be some sort of capping to the vertical section. What you have modelled is effectively a fence [smile]

All these little things are conspiring to make the render look very unconvincing. If the details aren't fully resolved, you can't really try to add too much entourage and background to make it look realistic. You are better off presenting the design as simply a 'realistic-looking' render with a simplified (or no) background.

The erode plugin is nothing like the sandbox tools.


That which does not kill us makes us stronger
-Friedrich Nietzsche

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