Very high polygon radiosity issue


I’m trying to render a huge model (nope, I’m afraid it can’t be smaller, it is a very big and highly detailed building: a cathedral). The .blend file containing it is 250mb, after importing an 80mb .3ds file. This model was created outside Blender (it needs to be very accurate, up to a cm). I have managed to render it in Yafray, but I wanted to try it in the Blender Internal Renderer.

The problem is that when I try to start the radiosity process (the Collect Meshes button), my PC ends up without any free memory and the program crashes. I’ve tried increasing the pagefile size, but it doesn’t seem to help. I’ve also tried less complex renders, and they work fine.

I was just wondering if it is worth doing this in the Blender internal, or if it would be better to just leave it to Yafray (the thing is, I’d like to do an animated photorealistic walkthrough of it). And, if you think it’s worth using the internal renderer, what do you think I could do to get it to work?

Thanks in advance for your help!


(Core 2 Duo 6400, 2.13 GHz / 2GB RAM / ATI Radeon 1650 256 mb)

just render it with max even if you have unlisenced copy, maybe y make enough money to pay the lisence with it and its same as y had allready paid the lisence.

if you want to go the blender route, use yafray. its a far better renderer and has better global illumination than blender. can we please see any renders?

I see comments like that last one all the time and, simply put, that’s bullshit. YafRay’s better in who’s opinion? Definitely not mine. You get what, 1 layer, renders that take hours or days, and no ability to tune your renders on the fly? I can show you 100,000 things Blender’s render engine can do that YafRay will NEVER be able to do. I might get pissed off at Blender (read: myself) all the time but comments like that tick me off every time I read them because they’re simply not true and uneducated at best.

You do not have to bake radiosity, you can do it at render time and there are some SVN builds (by RCRuiz) at graphicall that have MUCH improved radiosity support which will allow you to use textures and vertex colors plus they allow you to create fake caustics. RCRuiz posted an image that even came close to producing a Sunflow quality render with his build. Combine that with Broken’s soft shadows and glossy reflect/refract and I don’t see any advantage to YafRay at all.

For render time radiosity don’t bake the radiosity, just select the emit material, go to the radiosity buttons, set your parameters without baking and enable the “Radio” button on Blender’s render tab. Render time radiosity does not alter your mesh at all but it is slooooow because it has to be calculated on every changed frame so it’s not exactly a rendering technique for animations unless you have or use a render farm or have a lot of time.

For some BLISTERING Blender radiosity renders see this thread:

100% Blender radiosity:

For a RCRUIZ build go here:

You can also find Broken’s builds with QMC reflect/refract/soft shadows on the site too.


First of all, thanks for the feedback! I will take a look at all this as soon as I can!!

I’m also uploading a rendering test I did some time ago on Yafray, so you can get a basic idea of what the model is like.

It is actually part of a virtual model of the first project for the Sagrada Família in Barcelona (part of this first project, which was also by Gaudí, was built) which I am doing as a job (which means I might have problems uploading the results later on because of copyright problems and all that… I’ll see what I can do about it!)

As I said, thanks for the feedback, I’ll keep you informed! (on the WIP part of the forums, I suppose)



Very nice model!
I’m sorry if I came across as dismissive of blender’s renderer, but in my opinion, yafray is better for this type of situation. In general, yafray’s raytracing is much faster than blenders, and its global illumination is much more animation friendly than blender’s radiosity. I find it much easier to get good lighting with yafray, but thats just my personal experience. Although, if you’ve got too many polygons for blender’s radiosity to handle, you might have to use yafray for GI.

I’ve never played around with any of the various builds floating around, but they’re probably worth a shot if you want to use blender’s internal renderer.

P.S. Whats your poly count so far?

It sounds like Blender may be needing > 2 GB of Memory. You mention a page file, so I take it you are using Windows. You may want to look into the “/3GB” switch for the Windows bootloader to see if it can give Blender a little more breathing room in terms of address space. It’s not really a solution, especially if you have < 3 GB of physical memory. (Without which I’m not even certain it’ll work.) A better solution to the issue of address space exhaustion (if you insist you really need every single one of those polygons at all times) would be a 64 bit OS + 64 bit build of Blender.

That said, your best bet will be to use a vastly simpler model, bake the radiosity into lightmaps, and then use the lightmaps on the full resolution model for final rendering. Only use really high resolution lightmaps+geometry in the baking model in places where you are absolutely certain the camera will be very close to.