Particle advection/camera projection

Discussion and Support of Krakatoa Volumetric Particle Renderer for Autodesk Maya on Linux, OSX and Microsoft Windows
litote
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Particle advection/camera projection

Postby litote » Tue Aug 22, 2017 4:54 am

Hello,

In Bobo's webinars he shows a car being turned to dust. I have been able to achieve this effect with the C4D Krakatoa plugin using TFD and camera projection. Is camera projection also the method used in the Krakatoa for Maya plugin for this effect? Can someone tell me the steps, or better still, point me to a tutorial? I have no idea how to link up the camera projection with Krakatoa -- assuming that is the method used.

As a secondary question, I also tried using Maya's 2D container with Fluids-Add/Edit Contents-Paint Fluids Tool to convert an image to particles, but don't know if it is possible to use another emitter inside the container to further drive the particles, though I can use Field/Sovers like Turbulence. Anyone happen to know?

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Bobo
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Re: Particle advection/camera projection

Postby Bobo » Tue Aug 22, 2017 6:58 pm

For the projection mapping effect in Krakatoa for Maya, I used a custom Magma setup to generate the sticky UV coordinates, and then mapped a texture using them. It is the last video on the KMY Magma Webinar page: http://www.thinkboxsoftware.com/krakato ... a-webinar/

I believe the actual flow was posted somewhere at some point, but I am on the road today, so I might be unable to find it immediately...
Borislav "Bobo" Petrov
Product Specialist
Thinkbox Software Inc.

litote
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Re: Particle advection/camera projection

Postby litote » Fri Aug 25, 2017 2:52 pm

Thanks for your reply Borislav. I appreciated your series of webinars for Krakatoa for C4D. Now I am making the shift to Maya and learning the workflow all over again. I will definitely watch that Maya webinar.

Please post the flow or whatever further details that are available when you have time.

This disintegration effect is what I am aiming to reproduce in Maya -- I created it using Krakatoa with C4D/X-Particles/TFD (effect is at 1:28 in the reel) :
https://reels.creativecow.net/e/23270


Many thanks!

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Bobo
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Re: Particle advection/camera projection

Postby Bobo » Fri Aug 25, 2017 3:54 pm

Poor Miley :lol:

I knew I had posted about this before, did a quick search and found this thread, which also contains the link to the sample scene with the Magma in it: https://forums.thinkboxsoftware.com/vie ... 4&t=11753&

Please read the thread, download the scene, and let me know if you have any further questions...
Borislav "Bobo" Petrov
Product Specialist
Thinkbox Software Inc.

litote
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Re: Particle advection/camera projection

Postby litote » Sat Aug 26, 2017 3:02 am

Thank you Borislav,

I will be read through the thread and dissect the project file and try to recreate this.

Much appreciated,
Greg

litote
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Re: Particle advection/camera projection

Postby litote » Thu Oct 26, 2017 5:24 am

Hello Borislav,

I seem to have gotten about 99% of the way in recreating your scene file, however I seem to be missing one essential step.

I am able to render a single frame OK, but when I try to Batch Render I get this error:
// Rendering with Krakatoa... //
// Percentage of rendering done: 0 (Krakatoa MY: ERROR : material_evaluation_particle_istream error: The specified UVW channel: TextureCoord does not appear in the delegate stream's native channel map.) //
// Rendering Completed. See Console for more information. //


I can Batch Render if i do not add an image to the PRTApplyTexture-Texture slot. It will render the plain Texture colour OK as a batch Render without error. I am just using a simple Maya Cube with the default UV map.

Any suggestion? Is there something I need to do to fix "the specified UVW channel: TextureCoord does not appear in the delegate stream's native channel map" error?

I can render your scene file of the rabit OK with a substituted image for the Texture field, so I don't think its a bug in my Maya 2017 update 4 for Mac/OSX.

Thanks,
Greg

litote
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Re: Particle advection/camera projection

Postby litote » Thu Oct 26, 2017 5:59 am

Scratch that -- I noticed you had deactivated the PRTApplyTexture item in the Modifier Editor, so I also deactivated it and now it seems to work for the Batch render. Is that right?

litote
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Re: Particle advection/camera projection

Postby litote » Fri Oct 27, 2017 5:00 am

I was wrong about deactivating the PRTApplyTexture item in the Modifier Editor -- then the image won't be projected onto the particles. But what is causing the Batch Render error? What step am I missing in my setup?

Also, should the Channel Selection for the PRTApplyTexture item in the MOD editor be set to Color? In your example file it is set to Emission, and this seems to render other colours, not the texture.

Could I send my project file to you to check it over?

litote
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Re: Particle advection/camera projection

Postby litote » Fri Oct 27, 2017 5:57 am

Sorry for the string of posts.

I discovered what was causing the error -- Krakatoa will return an error if you render from a frame with no particles, hence I advanced the star frame for the render to when the particles appeared.

Can you confirm that the Channel Selection for the PRTApplyTexture item in the MOD editor be set to Color? In your example file it is set to Emission, and this seems to render other colours, not the texture.

Thanks

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Bobo
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Re: Particle advection/camera projection

Postby Bobo » Fri Oct 27, 2017 11:07 am

litote wrote:Can you confirm that the Channel Selection for the PRTApplyTexture item in the MOD editor be set to Color? In your example file it is set to Emission, and this seems to render other colours, not the texture.


It depends on how Krakatoa is set up. The reason my example used Emission is that I did not apply any dynamic lighting to the particles. The Color channel is used as the Scatter color when lights are involved. But lights in Krakatoa always produce shadows from particles onto particles. Since the projected image is generally already pre-lit (the non-Krakatoa renderer calculated its own lighting), all we want are self-illuminated solid pixels floating in 3D space. Thus, setting the Emission channel to the color from the texture, and setting Krakatoa to Use Emission while ignoring the scene lighting is the right thing to do. Then play with the balance of the Final Pass Density and Emission Strength to dial in the Emission color to a level that is not overbright and reproduces the original rendering as faithfully as possible.
Borislav "Bobo" Petrov
Product Specialist
Thinkbox Software Inc.


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