View Full Version : Cinema 4d memory problem

02 February 2008, 07:35 PM
Lately I've been trying to render a field scene, having a large field and using a hair renderer for grass. When I tried it on a small area it looks great. But I needed a relatively large field I simply used a bigger landscape and turn the hair count way up. I turned it up to 300000 hairs and 100000 fill hairs and it worked fast and fine. But it wasn't nearly enough to cover the field, so I turned the hairs up to 700000 and the fill hairs up to 500000 and now when I render the scene I get the error "Not enough memory...". But I look at my RAM counter and I usually have about 1.2 GBs free. Even if it did run out of RAM why doesn't it use my swap file? And is there a more efficient way to render a large amount of grass?

Any help is greatly appreciated! :D

02 February 2008, 07:44 PM
Not an answer to the memory question (might find something with the search function)

Is this for an animation or still?

You could render in sections (back, middle, and foreground) and comp them together in post.

02 February 2008, 07:54 PM
This will be for a short animation, probably about 1 minute and 45 seconds. :)

Is the hair renderer best used for small areas?

02 February 2008, 08:58 PM
Hi Kai, love the name ;)

First thing, get rid of fill hairs they are a nasty evil feature. Instead use the Fur object for your Filling of hairs

Second, how many segment are you using. reducing one segment can greatly reduce the overall scenes as your actually reducing as many segments as there are hairs, so if you have 300 000 hairs and you reduce one segments thats 300 000 segments less.

What is your gras doing, its it blowing in the wind or anything or is it just plain short cut grass. If its shortcut grass delete your hair object and just use fur for the whole entire thing. The fur object calculate the hairs as its rendering them this is a huge reduction in memory usage.

Also, in your render settings, you may have to use lines, line rendering splits up the hairs so fewer hairs are in memory at one time. This can often slow down your rendering time. but if memory is using your swap file, trust me you'll be surprised how much faster a render goes if it doesn't have to use your swap.

02 February 2008, 07:47 PM
Thanks to both of you, and yes, strangly coincidental Kai(LucentDreams). :P Great name.

Anyway, true that I could composite layers in post but if I use line rendering like LucentDreams said I should be fine. I switched the hair object a fur object and it seems to be working great! My only question is, there's no way to get the grass to blow in the wind when it's now a fur object, is there?

Thanks for the help so far! :D

02 February 2008, 09:22 PM
ehhh not eaily and the grass won't "bend along the hair, only at the root. Thats the one limit with the Furr object. The Fill hairs are kind of the same idea but are riddled with issues and problems.

If the grass just has to move a little and not bend along the strands, then you can animate a vertex map, but sadly this will require the mograph module. Basically you can have a weight effector object drive a vertex map making a fully animatable weight map. the reason you need mogrpah is for the weight node.

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02 February 2008, 09:22 PM
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