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Rendering is never fast enough – we always want better images faster, and it can seem that no matter what, the better the image, the longer it will take.

That might be true the majority of the time, but fortunately we have a list of small tips and tricks you can use to speed up your render time, regardless of scene complexity. Check ’em out;

1) Disable shadows (caustics) for glass.

Shadows on or off comparison

Model downloaded from GrabCAD.

Often times you simply don’t need the shadows cast by a translucent object –  great use for this is when you have headlights or window panes, where the primary visual effect is the reflections.

2) Avoid enclosing your light sources.

The image on the right has separate spherical geometry behind the glass pane, where on the left the glass pane itself is the emitter.

The image on the right has separate spherical geometry behind the glass pane, where on the left the glass pane itself is the emitter.

Putting a light source behind another object increases the amount of calculations required to render that emitted light. If the emitter was free-floating, many of those rays may only bounce once or twice – when they are enclosed, they all must bounce, and in the case of the headlights above, almost all of them also have to transmit through the translucent lens cap, slowing down render time considerably.

 

3) Keep your subobject/part counts low.

Not only is this model slower to render, but it is also harder to work with due to it's long list of subobjects.

Not only is this model slower to render, but it is also harder to work with due to it’s long list of subobjects. Model downloaded from GrabCAD.

The more individually movable parts you have in your scene, the longer your render times. Keep your renders quick by simplifying the math and merging like objects together.

 

4) If you can’t see it – hide it!

In this image, the "Visible" box has been left checked for demonstration purposes.

In this image, the “Visible” box has been left checked for demonstration purposes.

Even if you do not see an object in the viewport, it is still being considered in the program’s lighting calculations. In the interests of efficiency, it’s best if you just turn unseen objects off. In Lagoa this can be done by unchecking the “Visible” box in the mesh’s properties panel.

 

5) Be efficient with your lighting.

The fewer lights you have in a scene, the quicker it will be to finish rendering.

The fewer lights you have in a scene, the quicker it will be to finish rendering.

The more light sources you have, the longer it will take. This one is pretty obvious – the more lights the scene has, the more calculations the system has to run. As all of those light reflections start to interact with each other and different parts of the scene, your render time can go up pretty rapidly. Minimize the amount of light emitters. Sphere and dome lights are the most efficient lights to render. Remember that you can do a lot of lighting effects in post using an image editor such as Photoshop or GIMP.

 

6) Avoid high reflectance values.

Notice how the ball on the far right is blown out, with very little shading detail.

Notice how the ball on the far right is blown out, with very little shading detail.

Albedo is a measure from 0 to 1 (0% to 100%) of the light reflected off an object or material. Would-be render artists would do well to keep their reflectance values below .7 (70%). Otherwise, not only will your image render more slowly, but you will also be greeted by washed-out colors in the final result. In reality, light reflectance usually never goes above this number – as a rule of thumb, light skin reflectance is 0.4 to 0.5, whereas white paint is around 0.7.

 

 7) Try the “Simple Volume” material first.

Simple Volume vs Rough Transluscent

When using a material that relies on volumetrics or sub-surface scattering, try using this material first – it is the fastest and easiest to control. For more accurate results you can use the ‘Rough Translucent Volume’ shader which is based on real physical quantities instead of approximations.

 

8) Avoid overlapping geometry.

Even though the scene on the right has more geometric detail, it produces better results faster than the one on the left.

Even though the scene on the right has more geometric detail, it produces better results faster than the one on the left.

Try to avoid having geometry in the same exact position. Not only does it slow your render down, but it can introduce rendering errors and noise into your scene. It’s better to split this into multiple, non overlapping polygons rather than having a few very large overlapping faces.

 

9) Turn off “See objects Inside”

Notice how even when "Show Objects Inside" is unchecked, the object behind the sphere can still be seen through it.

Noticewhen “Show Objects Inside” is unchecked, the orb behind the sphere can still be seen, but the sphere contained within is no longer visible.

When you are using a volumetric/transparent material, you can reduce your render times by deselecting this option if you do not plan to put anything inside the object. It will act as if it were transparent (so you can see objects behind it), but Lagoa will not try to calculate any objects that might be contained within it.

 

10)Avoid strong indirect (bounced) lighting.

The image on the left shows noise that can be generated by strong indirect lighting. On the right, make sure to assign a black diffuse to your mesh lights.

The image on the left shows noise that can be generated by strong indirect lighting. On the right, make sure to assign a black diffuse to your mesh lights.

Strong indirect lighting tends to generate a lot of noise in the final render – so try to avoid situations where this would occur. Mesh lights in particular are prone to this issue due to complex geometry allowing for self-interreflections. For very bright meshlights that are not meant to reflect or refract light, apply a black diffuse material.

 

So there you have it – some simple things you can do to speed up your rendering and improve the quality of your final images. Most of these tips can be applied to all rendering software, not just Lagoa. If you have more ideas, let us know in our comments section or on our Facebook page.

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