Recommended PC specs for lightmapping in Unity 5?

Hello all,

My team is in the process of rendering lightmaps for our game, and it's taking hours per iteration. We're looking to get a high spec PC for lightmapping with, but I couldn't find any recommended specs online for such a thing.

Does anyone have any recommended PC specs to enable fast rendering times for Unity 5 lightmaps?

 

I suppose it follows the rules of a render farm unit, just try to cram as many threads as possible inn it and make sure it has enough ram to hold temp data. And ignore everything else.

edit: preferably more cores than faster cores.

 

Bake time is heavily CPU based. You can check CPU scores in Passmark site before buy it.
My test results :

1. G1840 - Score 3000
2. Laptop i7 - Score 6000
3. i7 4790K - score 10000-11000

Test 1: Unity 4
1. Bake time : 6 min
2. Bake time : 3 min
3. Bake time : 1 min

Test 2: Unity 4
2. Bake time : 12 min
3. Bake time : 3-4 min

Also you need +16gb system memory (RAM) and recommended 100gb SSD drive for GI Cache

 

Answering my own question in case anyone else finds it useful!

The following are anecdotal findings from a recent hardware upgrade. Results may vary.

Hardware Spec Guide:

• The general rule is that both RAM and the number of cores improve your render times.
• The number of cores seem to have a linear correlation to render speeds. In other words, doubling the number of cores doubles the overall render times. However, at the time of writing, there is a known bug that causes Unity to crash when the computer has 32 cores or more (https://fogbugz.unity3d.com/f/cases/889434/).
• RAM helps, but it has a level of diminishing returns. At around 32GB, Unity does not seem to utilise 100% of the RAM when rendering.
• The use of an SSD hard drive (for both your source data and your GI cache) will improve your render times by around 60%.

Other lightmap optimisation techniques for large scenes:

• Disabling Final Gather (assuming default settings) will reduce your render times by around 45%.
• Selectively reducing the cluster resolution is 100% essential for large scenes! It can make the difference between 50 hour renders and 30 minute renders.
• Using the preset lighting param “Default-LowResolution” is a good starting point regarding cluster res. Typically, the “Default-HighResolution” preset is for fixing lighting artefacts in special cases. Turning it on for the whole scene will massively increase render times for almost no discernible quality improvement. It only affects GI, so the final lightmap resolution is unaffected.
• Although reducing indirect resolution will help with render times, it does have a visible impact on the quality of the GI. Anecdotally speaking, a value of 1 seems to suffice in most cases.

Useful info:

https://unity3d.com/learn/tutorials/topics/graphics/introduction-precomputed-realtime-gi