Rendering exterior scenes with foliage - crash

[Czaja]

I'm testing V-Ray for Unreal with some exterior scenes. So far without a success. Before anything shows in the frame buffer, V-ray eats a whole 32 GB of RAM and then UE4 crashes. I attach some example view of V-Ray camera and view of the surroundings not visible in the render viewport.

[Czaja]

It looks like there is only about ~2,3 milion pixels in the viewport, yet UE4 crashes when I try to render. When I tried the same props with just a few ferns it worked ok. I would like to know more about it.

[Alexander.Atanasov]

Hi, Czaja

Sorry for the late response. When using the foliage system you have to keep in mind that all that polygons have to be loaded into memory and rendered. Unreal, as a rasterizer render engine only renders whats in the frustum of the camera, meaning that if you have 1million ferns but you are zoomed to only a couple, only those will be load into memory and not the other. V-Ray on the other hand loads all the assets into memory whether they are visible in the camera or not and buffers them all into memory.
Another note, the foliage system is optimized in handling lots of polygons. If you make the same amount of ferns into actors in the viewport, performance will drop greatly. As a suggestion I recommend, when using the foliage system to use static meshes that have been imported from vrmeshes. Vrmeshes are optimized in V-Ray to handle large amounts of polygons and will be very efficient in performance when used in the foliage system. Please read the following thread where a similar problem was discussed: Foliage workflow

Best regards,
Alexander