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Position Pass and Point Cloud

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raphaelgoesm

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Position Pass and Point Cloud

PostMon Sep 26, 2022 6:30 pm

Hello everybody. Is there any way to use the Position Pass of a render to generate a Point Cloud?
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Chad Capeland

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Re: Position Pass and Point Cloud

PostMon Sep 26, 2022 9:50 pm

What do you intend to do with it?
Chad Capeland
Indicated, LLC
www.floweffects.com
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Hendrik Proosa

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Re: Position Pass and Point Cloud

PostTue Sep 27, 2022 7:07 am

I guess the main use case usually is to help with placement of objects in scene. Point cloud helps visualize the space.
I do stuff.
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raphaelgoesm

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Re: Position Pass and Point Cloud

PostTue Sep 27, 2022 12:35 pm

Chad Capeland wrote:What do you intend to do with it?


Hi, i would like to be able to use the Point Cloud as references for the scenes made in Blender, without having to load all the mesh modeled there, to place more elements such as fire, smoke, rain etc...

An aproach like nuke, something like that:



I even found some topics:

viewtopic.php?t=52401

viewtopic.php?f=22&t=100966

But, both techniques depend on you having the 3D camera... And sometimes we don't have it available or when I tried to export from blender it doesn't match with the pass..
Last edited by raphaelgoesm on Tue Sep 27, 2022 12:39 pm, edited 1 time in total.
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raphaelgoesm

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Re: Position Pass and Point Cloud

PostTue Sep 27, 2022 12:36 pm

Hendrik Proosa wrote:I guess the main use case usually is to help with placement of objects in scene. Point cloud helps visualize the space.


Exactly ;)
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Chad Capeland

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Re: Position Pass and Point Cloud

PostTue Sep 27, 2022 2:37 pm

pImageEmitter and pCustom should be able to do that. I use that setup for doing stereoscopic visualization.
Chad Capeland
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www.floweffects.com
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Bryan Ray

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Re: Position Pass and Point Cloud

PostWed Sep 28, 2022 1:10 am

I usually use a Shape3D set to Plane and Displace3D in Absolute mode. Increase the subdivs on the plane until it has sufficient resolution to represent your scene, and you'll have a replica thereof.

As a bonus, if you have the camera, too, you can use this displaced mesh as a shadow catcher or matte object for any other 3d elements you add.
Bryan Ray
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raphaelgoesm

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Re: Position Pass and Point Cloud

PostWed Sep 28, 2022 12:55 pm

Hi, thanks for replying ;)

I tested both technique you guys describe. The problem is that Blender's camera doesn't match Fusion's Render. How do you deal with it?

One thing that's been coming to mind that maybe it's because of all the Blender´s madness operating with Z up...?
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Hendrik Proosa

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Re: Position Pass and Point Cloud

PostWed Sep 28, 2022 1:35 pm

You can change coordsys by swapping Y and Z channels (green and blue in rgb terms) and negating as necessary.
I do stuff.
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Jacob Danell

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Re: Position Pass and Point Cloud

PostThu Sep 29, 2022 1:11 pm

raphaelgoesm wrote:I tested both technique you guys describe. The problem is that Blender's camera doesn't match Fusion's Render. How do you deal with it?


It might be Resolution Gate Fit from Height to Width in the Camera3D node. You find it under the Controls tab and then under Film Back.
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