Displacement precompute time takes too long in Backburner

[diogovb]

Hello, is there a way to just pre-compute the displacement only when its available (like, just when Backburner render the strip that contains the grass with displacement), or otherwise do not pre computate it. When trying to render a scene in Backburner (the scene is big and have a lot of displacement and geometry) It takes TOO long to pre-calculate. Even if I strip the image in 50 parts. Even a 5px strip takes about 10 minutes to calculate everything. The backburner saves a lot of memory when stripping an image but this time to precalculate is weird. Is there a way to proceed? I hope you understand my question. Thank you!

[romullus]

Even if it's not visible directly, displaced geometry still affects whole scene - light bounces from surface, other materials can show it through reflection and refraction. I think you'd notice immediatly if some parts of image would be rendered with displacement and some without.

[maru]

What are your displacement settings?

Another thing I realized is that displacement can sometimes create really unwanted results. Here is an example. Imagine this as an animation where camera moves. The shadows would literally dance around. But I guess this is just just supposed to happen...?

[diogovb]

Yes this is strange. Well my displacement settings are: Screen space: 0,5  (there is just one, isnt it?). Of course it is a huge field, the displacement makes the grass. But couldn't I render this? The image attached is a painful render that took half a day to finish. Isnt the new displacement "adaptive" to camera? Why take so long to render? Even in 5px strips. Its so strange.

[maru]

Screen space: 0,5

There is your problem.
Why did you even change it?
Please revert to 1, or even increase it (slightly! like 1.1, 1.2, etc) if there isn't much difference in image quality.

Which Corona version are you using? It should be called "screen size" and there is also "world size" (which you shouldn't be touching).


What image resolution are you rendering?

Why do you even need displacement for image like this?

[romullus]

Unless you're rendering 800x600 resolution image, displacement subdivision at 0.5 px is unreasonable waste of resourses, IMHO. You may want to look at this tutorial - Ludvík shows that you can achieve almost as good results with much lower subdivision:

[diogovb]

Well, first. This image was rendering with 3000px with corona 1.3... I tried to use 1,0 or even bigger screen SIZE (sorry my mistake) but it wasnt as good as 0,5 quality. 1,0 gaves me a very "ugly" grass. And a displacement in the grass was very necessary since without it it wasnt good as I wanted it to be, simply.

[diogovb]

Romullus thank you for the video. It explained everything. This is not a feature that Corona actually have. But I'll wait for it. Maybe in next daily build. Haha thank you!

[maru]

Are you using displacement to make grass?

[diogovb]

Yes I was...