View topic - How to Render onto a Photo Background?

How to Render onto a Photo Background?

General discussion on lighting, backgrounds, Global Illumination, rendering parameters and tonnemapping.

How to Render onto a Photo Background?

Post Sat Oct 29, 2016 5:07 am

Hello!
I tried make object and put on the Photo. But I don"t know how make shadow on image.
I try use method by use Object index like this tutorial.
https://www.blenderguru.com/tutorials/r ... ackground/
It work with Cycles render. But with Yafaray I can't achieve this result.
Somebody know how put on image the Object with shadow?
AleksLion
 
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Re: How to Render onto a Photo Background?

Post Mon Oct 31, 2016 9:12 pm

A shadow pass is available now using Yafaray v3

Untitled.jpg
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stoneage
 
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Re: How to Render onto a Photo Background?

Post Tue Nov 01, 2016 8:48 am

Hello,

I believe that what you want is to use the ObjectID/MaterialID "Mask" render passes.

This functionality allows you to generate a separate image of certain objects (with or without their shadows) excluding the rest, so they can be composited onto a real image using Alpha compositing.

I've attached an example .blend for your reference. I hope you find it useful.

I've also attached a PNG with Alpha containing the result of the "Mask" pass so you can test to compose it on top of a real image.

cornellbox-yafaray-shadow-mask - 001 [pass obj-index-mask-all].png
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cornellbox-yafaray-shadow-mask.blend.zip
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David Bluecame
 
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Re: How to Render onto a Photo Background?

Post Tue Nov 01, 2016 8:54 am

Using the "mask" PNG above and compositing it onto a real grass image, I get this for example. I hope this is similar to what you want to achieve.

composed.jpg
composed.jpg (104.51 KiB) Viewed 7165 times


In Blender you can also achieve this using the Composite Node and getting the "Object ID" / "Material ID" Mask Render Passes from YafaRay.
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David Bluecame
 
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Re: How to Render onto a Photo Background?

Post Thu Nov 10, 2016 5:25 pm

I think what he wants is to have a shadow catcher material. What is a must for this sort of compositions.

This is luxrender's version.
http://www.luxrender.net/wiki/Shadowcatcher

In vray, there is a matte material, which can only show certain properties, for example, shadow.

https://www.vray.com/vray_for_3ds_max/manual/vraymtlwrapper.shtml
surena
 
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