Hi everyone,

I'm starting a little project : water flowing into a pipe, taking two coke cans with it.
(I'm still caching the sim, but it's taking a looot of time… And by the way : is 0.009 a good particle separation ?)

I just have two questions for the moment :

- I have two portal lights, are those lights long to render ?

My pixel sample is 6 by 6 (maybe too much), my noise level 0.01, max ray samples to 10, diffuse limit to 1, and pixel filter in gaussian 2 2. Those are the only settings I changed. But even with lower samples, the render is still too much long… (my spec : 8go ram, Core i7 2.20GHz, GT540M)

- Why is the render taking 35 minutes for this simple image ? I really mean 35min… And the resolution is only 768x431 !


Thanks,

Lewul.

(sorry for my bad english)

Hi Lewul,

It's pretty hard to diagnose why the render is so slow without a HIP file; there could be many reasons. If you can't post that specific HIP file, is there a different example you could post that has the same problem, in order to help figure out what's going on?

I had an example a while back that was taking about 45 minutes per frame, and with a pair of small changes to the rendering and shader settings, it was down to about 30 seconds per frame with just as good quality. :wink:

Here is the HIP file ! But I don't have another example with the same problem

EDIT : it was not the good version of my project, so I replaced it by another one (the good one).

you can use render farm to reduce render time.

This is not the question, I'm just trying to optimize my render on my computer !

Hey Lewul!
I checked your file quickly!
First you are using .png as your texture maps and .jpg for your displace.
Both formats aren't the best to use. Try converting them to .rat
Check the second Tip:
http://www.sidefx.com/docs/houdini12.5/io/formats/image_formats [sidefx.com]

Did some renders test without the Textures and displacement maps( since I don't have them), and it didn't seem that slow.. but was able to get it faster and a better quality..

Set your pixel sample to 8 X 8
remove sample lock if your doing a render of sequence.
min max Ray sample to 3 6
set your noise Level lower than 0.01 for final renders


BTW: what's your machine specs.
let me know if that helps.
lari

Hey,

Thanks for your answer ! I'm stupid I should have given you the images…
My spec : my spec : 8go ram, Core i7 2.20GHz, GT540M.
The size of the pipe texture is very large (I'm not in my computer currently, I don't remember the size).

How much time does it take on your machine ?

And it's even longer with the water…

So its taking me around a minute and a half on my machine.
I did forget to mention in my last reply about the lights in your scene.. You have the Sampling Quality to 3.
By default if you leave it to 1 it will take your mantra min and max ray samples. So a value of 3 is like “multiplying” your mantra samples by 3 for those lights which will cause the render to be slower… but in your case I lowered it back to 1 and the quality was still similar so I kept it low and played with the mantra sampling and it was way faster like that.

Personally I'm not a big fan of .png and .jpg for textures. Try working with .rat files. You can always save TGA, TIFF, EXR from what ever software you use and then convert them to rat files.

I didn't have time to test with the water sim, for sure it will add more time to your render since you have refraction but it shouldn't take that much more. You might want to higher the Min Max Ray Samples to get a good Final result.

lari

Oh yeap, you're right 3 is a bit high…

About the fluid, when I cache the simulation then I read it back but I don't know what parameter I have to change in the “particle_fluid” node to see the geometry from my sim data. It seems that I only want to make a geometry from particles that are coming from my “flipfluidobject” but not from my cache date ! How can I fix it ?

Thanks.

Were you caching data from within the DOP netowork? I'd rather cache the geo from the particle_fluid geo container as it's leaner and, in your case, if all you want is to surface it later that's all you'll ever need.
I'm not sure what you mean by the parameter you need to change to see the surface… do you care to elaborate?

Cheers

Yes exactly, you are caching your DOP network by checking the Explicit Cache and the output is a .sim file… That's not what you need to do if you only want to cache your Flip particles and then the mesh…
I would do a 2 step process for that…
1- cache the Flip particles
2- cache the mesh…

First uncheck Explicit cache, and go in your particle_fluid node. In the import_particle node you have the options to write on disk your particles as .bgeo.

Second step would be to read your cached particle by checking the load from disk and then cache the mesh with surface_cache.

Hope it helps!

lari

rafaels : the surface of the fluid created for render, I don't know how to explain…


The thing is that yes I want the particles, but there are two cans falling in my scene, saw I also have to cache the rbd simulation. I put a “file” node at the end of my dop network tree and cache everything, and it seems to work. But then I want to see my geometry “made by” the particles, for my water surface, and I don't know how to do.

But I think Larikaram gave me the answer :

“Second step would be to read your cached particle by checking the load from disk and then cache the mesh with surface_cache. ”

When I do this, nothing happens, and maybe it is because I alsow have my rbd simulation in my sim data… Right ?

So, how can I separate rbd simulation and fluid simulation for caching ?

Thanks !

In your Canette SOP after your dopimport1 add the rop output driver to write the rbd and then read it with a file node or use the file_cache node which also works!

lari

Right, I'll test this tonight ! The file node in the Canette SOP ?

yes after your dopimport1 node

lari

Ok thanks Lari !

Ok… I have an other problem, I was starting to create a wet map for the “tuyaux” object (the pipe), and of course : the simulation started to react differently. The fluid was just falling down without reacting with pipe, and the cans neither. So I reset the simulation, and the fluid react with the pipe, but not the cans. And I don't know where the problem is coming from…

I feel a bit retarded with this scene.

Hey Lewul,
I attached your scene with notes inside! every thing seem working goooood!
Its all about your collision objects when using Bullet….

hope it helps!

Wow dude thanks a lot ! And also for the website
This morning I tried to convert the pipe into a terrain object instead of a static object, and it worked ! Strange… But it works fine with the RBD solver !

No problem!
Both Bullet and RBD worked fine with me!
You should be able to make them both work as I mentioned in the notes!
Always visualize your collision mesh before you sim!
enjoy
lari