How to render object with shadow and transparency?

[Anonymous]

Hi, I have attached a Maya file here. How to render the object with shadow only and transparency. So I can use this file in After Effects.

[sean.heasley]

Hi @Anonymous and welcome to the community!

Shadow passes are dependent on the full Arnold Render and cannot be rendered individually - mathematically, the shadows are dependent on the calculations of the beauty render. 

To preserve memory, create a new layer and apply a flat white shader to all objects in the scene, and then render the Shadow Pass. Removing complex textures will lessen overall render times and still provide the necessary information for a successful (and accurate) render.

The same process can be done for the transparency only have the transparency shaders on and a flat white shader on everything else.

Please let me know if this helps or if you need any more assistance!

If one or more of these posts helped answer your question, please click Accept as Solution on the posts that helped you so others in the community can find them easily.

Kudos are greatly appreciated. Everyone likes a thumbs up!

[Anonymous]

Hi Sean, I want exactly same as rendered file that I attached. So the image will be alpha in Photoshop.

[sean.heasley]

Hi @Anonymous

So you want the same render but you want the black and white color so it would work as an alpha?

Please let me know if I understand this correctly or if I'm not please explain in more detail and I'll see what I can do to help you!

[sean.heasley]

Hi @Anonymous

Just wanted to check in to see how things were going. Are you still having this issue?

If your issue is resolved, please click Accept as Solution on the posts that helped you so others in the community can find them easily.

[Anonymous]

Hi, do you mind if you can try the Maya file that I attached before? I want to know how to render the lorry and shadow only and it will work as an alpha. Thanks.

[sean.heasley]

Hi @Anonymous

Ah I think I misunderstood.

If you just want the shadow you can simply hide the truck from the render but still get the shadows.

To do this:

1. Select the object

2. Open the Attribute Editor (Ctrl + a)

3. Open out the Render Stats section

4. Un-tick Primary Visibilty but leave Cast Shadows turned on

If one or more of these posts helped answer your question, please click Accept as Solution on the posts that helped you so others in the community can find them easily.

Kudos are greatly appreciated. Everyone likes a thumbs up!

[Anonymous]

Hi, this is what I have rendered, but not what I want. I still want the truck with shadow. I don't want the road texture and I want it to be an alpha. But the thing is, the shadow is on road texture layer. If I turn off the road texture layer, the shadow will disappear.

[sean.heasley]

Hi @Anonymous

If you disable "Primary Visibility" in the Render Stats an object will not be rendered, it still can generate shadows, reflections and refractions on other objects but it will not receive them. So if you turn the visibility of your shadow-plane off you will not get any shadows on the plane.

You should enable "Primary Visibility" on the plane and you could use the "useBackground" shader on the plane so it will appear transparent but still have the shadows cast on it.

[Anonymous]

Hi, have you tried with the Maya file that I gave?

[Anonymous]

Hi, can you try to open the Maya file that I attached here and render it same as png file (Truck.png) in attachment below? (Truck.png is an alpha)  I just want to know how do you do it. Thanks.

[sean.heasley]

Hi @Anonymous

You can't get a render like the image you provided in just one shot.

There needs to be something there to catch the shadows that are being cast from the truck. So for example, if you have your truck moving and then have a plane underneath it there'll be shadows. However if you make that plain invisible you won't be able to see any shadows because they'll be hitting an invisible surface.

That's why I shared this article that gives a good breakdown on how to render the shadow passes.

[sean.heasley]

Hi @Anonymous

I'm just checking in again to see if you need more help with this. Did the suggestion I provided yesterday work for you?

If so, please click Accept as Solution on the posts that helped you so others in the community can find them easily.

[Anonymous]

1. Hi, how to do this? --> "assign it to the shadow catching object(s)"

2. And, how to do this too? --> "Select the objects(s) in the scene casting shadows"

Which one is "scene casting shadows"?

[mspeer]

Hi!

1. To nurbsPlaneShape2 assign new Arnold material aiShadowMatte.

2. Render with Arnold

That's it.

[Anonymous · Accepted solution]

Hi, I can't render Arnold, but I found a solution.

What I did, at 'nurbsPlane2' (object) in main window > right click > Assign Favourite Material or Assign New Material > Use Background.

Then, I rendered as Maya Hardware 2.0. It works!

So, I can use back the previous background just right click at 'nurbsPlane2' > Assign Existing Material > choose Floor (material that I used before).

Thanks for your help.

[Anonymous]

Hey,

I tried to get transparency with shadow. I took 1 cube placed on a plane, I wanted to tak only cube with shadow not the plane rendered in Arnold. I did the steps you mentioned like for plane primary visibility is on and used use background, then save the image as png. And also kept the plane in matte not in opaque. I got the cube in .png but without shadow.

[InfiniteeDesigns]

This may be what you are looking for...

Maya Tutorial: How To Use Arnold Shadow Catcher Material

https://www.youtube.com/watch?v=r4THrvUOedQ

[hgrahls]

You're a wizard. Thank you for this thread