How Do I Control Imported alembic Hair Colour Across a Surface?

[pali_rao]

I'm doing some hair tests and am using V-Ray Proxy to import an alembic file. I'm trying to get the colour of the hair to match the diffuse map for the object over the surface (not along the hair length), but I can't get it to work.

I'm not sure how to get the alembic to recognise the UV map for the object and then be able to apply to colours correctly.

Does anyone know how to do this please?

Many thanks!

[larry.vasquez]

Hi Pali_rao, check this out and see if this solves what you're looking for: https://vimeo.com/575451869

[pali_rao]

Thank you very much for replying so quickly and taking the time to make that video Larry! Much appreciated!! I did try to doing exactly that, but on further investigation, I think I'm running into issues as my alembic (from C4D was at a scale in centimetres and when it was imported by VRay Proxy, it was expecting the scale to be meters, so the alembic was huge. I scaled the VRay Proxy item to 1% and reset this to the new 100% and it renders ok, but the map is not being applied properly I suspect, but not sure how to fix this.

[larry.vasquez]

I'm bringing the Alembic in from Maya and it did the same thing. But it's working just fine as shown in the video. Can you link the Alembic and I can test?

[pali_rao]

Thank you Larry! Sure, I tried again bringing in a test alembic in which did not require scaling, and the same thing happens - please see attached - something weird is happening. I'm going to try rebuilding the scene too....

Did you have to do anything with the colours in Maya before export? Im using C4D to create the alembic, and didn't add any material to it before export...

[pali_rao]

Larry - I've just sent you a PM with a very simplified Modo scene file - with low poly geo, diffuse map and the alembic file - Im missing something but not sure what.....Thank for taking a look for me, much appreciated!

[larry.vasquez]

Hey pali_rao, I'm stumped with your scene. I'm doing the same thing that I did with my test and it's not working. I'm using Ornatrix in Maya for hair and exporting via Ornatrix Alembic. All the coloring is done in Modo. Is there anything in C4D on the export that you're doing color wise?

[pali_rao]

No worries at all - thanks for taking a look for me, much appreciated. I'm back on it now, so will continue experimenting.

[pali_rao]

I can get the abc file to changes colour with the VRay Material, but not with the texture file.

I don't understand how the alembic file will know how to apply the texture file, as it does not have a UV - how does it get this info fro the underlying geo?

[larry.vasquez]

You'll need to see if boyan can help.

[pali_rao]

Thanks buddy. Boyan is the the man - I've already emailed him and also Chaos support - I'll post back their finding here once it works, so everyone gets the solution...

[boyan]

Hey, Hey,

Thank you for the report/s. Not sure how that sounds but your reports did an amazing job. I will check it.

Cheers,

[pali_rao]

Thanks Boyan!! You are a superstar!

[boyan]

Ok, let's get in.

I highly recommend using V-Ray Hair NEXT material with a combination of V-Ray Proxy, you can drive the Diffuse with textures as well, please check the example test video. https://drive.google.com/file/d/1s9o...ew?usp=sharing
I hope this can help you, and sorry for the delay.

In addition: In order to set the texture map with UV for alembic file via V-Ray Proxy first, you need to set up the UV tag (before export to alembic). How to use it? 1. Create texture group locator inside V-Ray Proxy Item -> Next change the material set to polygon selection set (this will match the UV tag created before export of alembic file) https://drive.google.com/file/d/1o6M...ew?usp=sharing

Cheers,