Problems baking 4K maps in Cycles

Hi everyone,

Using Blender for a couple of weeks now and I must say that I’m very impressed about the cycles render engine
I’m currently working on an interior architecture project and I followed Blenderguru’s video tutorial about baking textures with Cycles. I basically want to bake all my shadows on to a hi-res map (2k or 4k maps).

It took quite a while to bake a 2k texture map with 24 samples, but considering my low-budget pc, I was quite satisfied about the end results. Then I went a step further and tried to bake a 4k texture map with 32 samples, but it didn’t work out. After more than 12 hours of baking, I gave up and canceled the baking job because I thought Blender wasn’t doing anything.

So guys, I’m wondering why it takes soooo long to bake a 4k map with high samples. I find this strange because I did Make Pan’s Cycles render benchmark file and it took me between 6-8 minutes to render his scene, while a 4k baked shadow texture takes ages. Why is that?

Here are my specs and benchmark results that I’ve posted in the benchmark thread:
CPU: Intel Core i5-2410M 2.30GHz
GPU: Nvidia GeForce GT 520MX
OS: Windows 7 64bit | Blender 2.71
Time: 8 min 12 seconds (GPU - CUDA)
Time: 6 min 36 seconds (CPU 4 threads)

I hope you guys can help me out, thanks in advance! (:


Hi, double size need 4 times RAM and with higher samples even more.
How much RAM do you have?
If the system start swapping on harddisk the performance is really slow.
If you only need shadow maps you can try Blender Internal bake system, it is much faster than Cycles system.

Cheers, mib
EDIT: In layer tab is a material slot overwrite all used materials, use this to setup a material for shadow baking with BI.

Thanks for your fast respond.

I have 8 GB ram installed on this laptop. Too bad I’m unfamiliar with Blender’s internal bake system. Could you please elaborate more on that part?

forgot to mention:What do you mean with ‘If the system start swapping on harddisk the performance is really slow.’?


Thanks for your fast reply.

I have 8 GB of ram running on this laptop. Too bad I’m not familiar with Blender’s internal render system. Could you please elaborate on that part?