Vray Proxy/Alembic Particle Question

[vladimir.nedev]

For tomorrow's nightly build (the one from 2015-08-16) I've added access to the particle attributes for shading.
V-Ray considers them vertex color sets, so they are accessed using MODO's weight map texture.

Note that bias/gain/color mixing of the weight map texture is not supported at the moment, the color from the Alembic/vrmesh file is returned directly.
Also note that the weight map texture still wouldn't work with MODO's meshes and vertex maps. I don't export MODO's vertex maps to V-Ray currently.

Here is how it looks on your file:



The V-Ray core/ply2vrmesh tool will merge scalar attributes like "age" into a single color channel, and will prefix the name with "r_", "g_" and "b_".
You can extract just one of these channels using the Schematic in MODO.

These vertex maps are not actually given to MODO though, you can only use them for shading with V-Ray. They won't work with Replicator instances either.

Greetings,
Vladimir Nedev

[Dentzz]

For tomorrow's nightly build (the one from 2015-08-16) I've added access to the particle attributes for shading.
V-Ray considers them vertex color sets, so they are accessed using MODO's weight map texture.

Note that bias/gain/color mixing of the weight map texture is not supported at the moment, the color from the Alembic/vrmesh file is returned directly.
Also note that the weight map texture still wouldn't work with MODO's meshes and vertex maps. I don't export MODO's vertex maps to V-Ray currently.

Here is how it looks on your file:

[ATTACH=CONFIG]25545[/ATTACH]

The V-Ray core/ply2vrmesh tool will merge scalar attributes like "age" into a single color channel, and will prefix the name with "r_", "g_" and "b_".
You can extract just one of these channels using the Schematic in MODO.

These vertex maps are not actually given to MODO though, you can only use them for shading with V-Ray. They won't work with Replicator instances either.

Greetings,
Vladimir Nedev

This sounds very cool looking forward to playing with it, though with everything particles it might take me awhile to actually get my head around it. But just being able to get a color channel out means lots of possibilities. On a related note if I want to enable motion blur on a proxy where would I set the motion blur samples?

I don't think the particle width/size can be changed once the .vrmesh file is created. It is locked in the file.
The direct Alembic rendering, as well as the ply2vrmesh tool will try to read radius/width data from the Alembic file, if it has it.
I am not sure but it might be possible to export the particles with their correct radius/width directly from Houdini, so you don't have to set a fix width with the "particle width mutliplier".

That seems like a great way to do it, if I set the value in Houdini I assume I should set it as "width" as opposed to "pscale" or do I need to create a "particleWidthMultiplier" value to be read by the proxy or ply2vrmesh? Houdini lets you set arbitrary values which can be good/bad compared to Modo which often does these things for you.

I am not sure how ply2vrmesh file works in this case, it might be loading the whole Alembic file into memory.
Can you check how much RAM it takes while running (if it's not crashing immediately of course).
How much RAM do you have ?

I'm still uploading the file it is about 30% done. The files typically seem to work, run but produce only a 1kb file or crash. One file I made when trying to create a file at a size that could be uploaded crashed when actually running the program. The one that crashed while running is actually larger than the file that I am sending which crashed immediately upon running the program. I have 64gb of ram on the system but it doesn't seem to show any extra ram being used while running ply2vrmesh, though it could just be that it is already assigned and not increasing.

[vladimir.nedev]

This sounds very cool looking forward to playing with it, though with everything particles it might take me awhile to actually get my head around it. But just being able to get a color channel out means lots of possibilities. On a related note if I want to enable motion blur on a proxy where would I set the motion blur samples?

For the internal movement of the particles, I think that only 2 motion blur samples are always used, since the motion blur is computed using the stored velocity.
If you animated the position of the whole V-Ray Proxy item, this animation can use more than 2 samples, but i haven't added the ability to specify this number in the UI of the V-Ray Proxy.

That seems like a great way to do it, if I set the value in Houdini I assume I should set it as "width" as opposed to "pscale" or do I need to create a "particleWidthMultiplier" value to be read by the proxy or ply2vrmesh? Houdini lets you set arbitrary values which can be good/bad compared to Modo which often does these things for you.

By looking at the code, I think "width" should be the correct one, but you should try it. It is certainly NOT "particleWidthMultiplier". The code also searches for an attribute named "radius" or ".radius", I am not sure about the dot, but this might be for particle data exported from some other application, not Houdini. Our Alembic guy is on vacation, so I can't ask him unfortunately.

I'm still uploading the file it is about 30% done. The files typically seem to work, run but produce only a 1kb file or crash. One file I made when trying to create a file at a size that could be uploaded crashed when actually running the program. The one that crashed while running is actually larger than the file that I am sending which crashed immediately upon running the program. I have 64gb of ram on the system but it doesn't seem to show any extra ram being used while running ply2vrmesh, though it could just be that it is already assigned and not increasing.

OneDrive gives me "We're unable to complete your request. Microsoft account is experiencing technical problems. Please try again later." when I try to download the file.

64GBs seems like it should be enough, so the amount of RAM might not be the issue after all.

Greetings,
Vladimir Nedev

[Dentzz]

Transferring the attribute from "pscale" to "width" worked and is working for both replicators and the proxy.

Try the one drive again I think it is working now or at least it worked when I tried it on someone else's computer 15 mins ago.

I tried the 2015.08.17 build but I wasn't able to access the attributes using the weight map I just see none under Vertex Map. Am I not doing something by not setting it up or is it not actually in yet?

Is it possible that ply2vrmesh is a 32 bit program and with all the particles and different attribute channels that exist in an alembic file maybe it somehow got to over the ~ 4 billion that a 2^32 file system could handle?

[vladimir.nedev]

Try the one drive again I think it is working now or at least it worked when I tried it on someone else's computer 15 mins ago.

Sorry, my mistake there, I was trying left clicking on it, but it seems it only works when you right click and select "download".

I tried the 2015.08.17 build but I wasn't able to access the attributes using the weight map I just see none under Vertex Map. Am I not doing something by not setting it up or is it not actually in yet?

It should be working. Did you load the Alembic/vrmesh file in a proxy, before looking at the Weight map texture ? Those vertex map names are coming from the Alembic/vrmesh file. It shows whatever is stored in the file.
What version of MODO are you using by the way ?

Is it possible that ply2vrmesh is a 32 bit program and with all the particles and different attribute channels that exist in an alembic file maybe it somehow got to over the ~ 4 billion that a 2^32 file system could handle?

It should be 64-bit. I think it has been tested on some pretty large files already.

Greetings,
Vladimir Nedev

[Dentzz]

Sorry, my mistake there, I was trying left clicking on it, but it seems it only works when you right click and select "download".

Glad it is working had never used One Drive but it was free and had a 10gb file upload limit.

It should be working. Did you load the Alembic/vrmesh file in a proxy, before looking at the Weight map texture? Those vertex map names are coming from the Alembic/vrmesh file. It shows whatever is stored in the file.
What version of MODO are you using by the way ?

I started with a new scene add then load the vray proxy/alembic file. In the shading tab I added a layer processing weight map texture. Have tried adding an item mask to the proxy and just having it on the scene. I'm using Modo 801 sp5, is this only working on 901?

[vladimir.nedev]

I started with a new scene add then load the vray proxy/alembic file. In the shading tab I added a layer processing weight map texture. Have tried adding an item mask to the proxy and just having it on the scene. I'm using Modo 801 sp5, is this only working on 901?

I tested only in 901, it is indeed not working in 701/801.
It seems MODO 701/801 want only RGBA vertex maps from plug-in geometry, and I am giving them RGB maps.
This was probably a bug that was fixed in 901.
Anyway, for tomorrow's nightly build ( 2015-08-18 ), I've fixed it for 701/801 by representing our color sets as RGBA.

Greetings,
Vladimir Nedev

[Dentzz]

Great have colors and particle size being able to be transferred. Can't figure out how to get motion blur to work but happy this is working at all. This is a large enough amount of particles which while I haven't tried the 901 deferred meshes crahes modo if I even attempt to bring it in as an alembic file instead of as a vray proxy.

[vladimir.nedev]

Can't figure out how to get motion blur to work

Looking at your file, and rendering the velocity with a weight map texture, it looks like the velocity is 0 for all particles. Might be some option at the export step from Houdini.

I tested the 14 GB Alembic file you sent me, and it indeed crashes ply2vrmesh. Interestingly, if I make a local build of ply2vrmesh, everything works correctly and I can convert the whole file to vrmesh.
Might be some weird compiler issue, as the official builds use the Intel compiler. We will investigate further.

When I was able to run ply2vrmesh, I realized that it only loads a single frame of the abc file while converting it. Since a single frame for this file is at most around 200MBs, that's pretty much the maximum amount of RAM that's required to run the tool on this file.
So, RAM is definitely not the problem here.

Greetings,
Vladimir Nedev

[Dentzz]

Looking at your file, and rendering the velocity with a weight map texture, it looks like the velocity is 0 for all particles. Might be some option at the export step from Houdini.

Ha, yes you are 100% correct, the particles velocity becomes 0 or close to 0 very soon after being created in the scene that was sent. Sorry for not being more clear but my motion blur not working issue was slightly different as I think I mentioned motion blur samples earlier in the thread and wasn't sure how to use them on particles.



On this scene which does have velocity the particles are able to blur but do so as going from point A - to point B like in the yellow line, but the direction should be in an arc like the red line. This could be an export issue and I need to add subframes or some other info to the alembic file, could be I don't have the right settings in Modo/Vray, also maybe attaching the particles to replicators so they would think of themselves as geo could possibly work.

I tested the 14 GB Alembic file you sent me, and it indeed crashes ply2vrmesh. Interestingly, if I make a local build of ply2vrmesh, everything works correctly and I can convert the whole file to vrmesh.
Might be some weird compiler issue, as the official builds use the Intel compiler. We will investigate further.

When I was able to run ply2vrmesh, I realized that it only loads a single frame of the abc file while converting it. Since a single frame for this file is at most around 200MBs, that's pretty much the maximum amount of RAM that's required to run the tool on this file.
So, RAM is definitely not the problem here.

Ah, that would be why it seemed like no ram was being used by ply2vrmesh.

Thanks

[vladimir.nedev]

On this scene which does have velocity the particles are able to blur but do so as going from point A - to point B like in the yellow line, but the direction should be in an arc like the red line. This could be an export issue and I need to add subframes or some other info to the alembic file, could be I don't have the right settings in Modo/Vray,

I think this is a limitation of the V-Ray Proxy at the moment, for deformation you can have only 2 motion blur samples. Deformation includes individual particle movement like in your case.

also maybe attaching the particles to replicators so they would think of themselves as geo could possibly work.

I don't think this will work either, as I am giving MODO only position/size information about the particles. I could give MODO the velocity, but that will create linear motion as well.

Greetings,
Vladimir Nedev

[vladimir.nedev]

For tomorrow's nightly build (2015.08.22) I have added UI for the Point Particle Material from V-Ray for 3dsMax/Maya.
It should be applied to V-Ray proxy particles in "Points" render mode.
You can read more about it here:
http://docs.chaosgroup.com/display/V...intParticleMtl

Note that we have some problems with the nightly builds, so the build may not be available tomorrow.

Greetings,
Vladimir Nedev

[Dentzz]

I don't think this will work either, as I am giving MODO only position/size information about the particles. I could give MODO the velocity, but that will create linear motion as well.

Could it possibly work if I baked the particles out as geometry?

For tomorrow's nightly build (2015.08.22) I have added UI for the Point Particle Material from V-Ray for 3dsMax/Maya.
It should be applied to V-Ray proxy particles in "Points" render mode.
You can read more about it here:
http://docs.chaosgroup.com/display/V...intParticleMtl

Interesting, is the main difference the phase function?

[vladimir.nedev]

Could it possibly work if I baked the particles out as geometry?

I don't think the particles could be baked as geometry at all.

Interesting, is the main difference the phase function?

I don't know how it works, but I think the main difference is that the particle is shaded as if it is part of a bigger volume, not surface.

Greetings,
Vladimir Nedev

[Dentzz]

I don't think the particles could be baked as geometry at all.

Well I guess I am out of ideas for the moment on this one.

the main difference is that the particle is shaded as if it is part of a bigger volume, not surface.

Not sure I understand what the impact this has exactly. Having not tested on much of anything seems to look the same but render slightly faster compared to just a normal vraymtl.

Not sure if this is something that takes a little more developer time but would it make sense to have a check box for use particle color like the max and maya versions look like they have? I like using the weight map texture and as long as it ends up in the documentation so people know about it, I think gives a lot more flexibility but I don't think it would be immediately obvious.