Octane Standalone: STORM - Alembic Particle Size Tweet

[leehenshall]

I'm trying to control the size of my imported Alembic particles from STORM.

Here is my test setup:

The render view performance is really impressive. But no matter what I do I can't seem to control the points size in Octane Standalone.

The Alembic import options offer a "Default Sphere Radius" option but it does not do anything:

My plan is to ORBX Proxy my simulation into C4D. The cache is difficult to load into C4D viewport so ORBX really does feel like the way to go for this. The lack of control over the look of my particles feels like a problem though.

As a side note I have also experimented with the particle rendering technique utilizing the scatter object in Octane for C4D. (I think this is coming to SA soon...pretty sure it was mentioned at GTC)

The basic workflow here is to import alembic particles as polygons:

Then use the polygon particles as vertex/surface object to scatter custom objects (in this case a small Platonic primitive)

This technique allows control over particle instance size and shape but I don't think it is possible to easily access particle attributes without somehow baking them to a vertex map. I also cannot get motion blur to work with this technique.

It is also prone to Optix errors and relies on being able to import the cache into the c4d viewport which isn't always possible with large cache files (this test was done with a 10% resolution test cache)

So I guess what I'm asking is how can I control my particle sizes when using Alembic particles via Octane standalone. Am I doing something wrong? I am asking in the STORM forums to find out whether I can do more within STORM to get my alembic particles to render smaller in Octane SA. There is an override for this in the STORM Alembic stitcher but I have that checked on and it does not make a difference when loading into Octane.

I'm investigating buying a licence of Krakatoa (STORM can also export .PRT & .BIN files which play nicely with Krakatoa) to see if that can make life easier. But I am reluctant to buy what is effectively a product that seems to be at the end of its Lifecyle.

I feel like Octane should be able to do this but I'm not sure if I am doing something wrong or whether the particle rendering tools in Octane should be improved.

Any help would be greatly appreciated.

For those interested here is a link to the thread on the STORM forums:

https://effectivetds.com/forum/viewtopic.php?f=112&t=1800

[leehenshall]

Here are my most recent findings for anyone who is interested in this topic:

It seems that if there is scale information in the Alembic Cache. Then the Alembic import controls for particles size in Octane Standalone are overridden by the information within the Alembic Cache. So it is important to bake this information before exporting for rendering.

It turns out Storms particle size (width) attribute baking tools work just fine. It was not giving the desired point size because I was not using low enough values. I mistakenly assumed that the (width) scalar value in the baking options used the same value as the viewport Point Size in the Global Settings. My workflow was to set the viewport Point Size to my desired size to get a visual preview of what my rendered points would look like. Then input those values into the Alembic Stitcher or Set-Attrib width value.

It turns out that the viewport Point Size and the Alembic Stitcher & Set-Attrib point size width overrides are not connected and different values need to be used. In this case a viewport point size of 0.01 needed to be 0.001 for the Alembic point size baking process.

Here are the revised results:

A three step process.

1- Create initial cache as Alembic Sequence

2- Scale Alembic sequence particles using the Set-Attrib (width) value & export as a Stitched Alembic

3- Delete idle particles using supplied expression @Cd.r == 1 && @Cd.g == 0

Step 1

Create Cache

Step 2

Scale Particles

Step 3

Delete Idle Particles

Now we ready for Octane Rendering. Here are the steps visualised in Octane Standalone:

Step 1

Create Cache

Step 2

Scale Particles

Step 3

Delete Idle Particles

This is enough proof of concept to progress with my project. I'll ask additional questions in a separate thread.

It would be nice to have more control within Octane to override point size as well as replace the default sphere with custom instances. But I am glad that I do not need to buy Krakatoa to get high density particles to render by working around the issue within Storm.

Hope someone else finds this helpful in the future