Exclude object but cast shadows

[elada20]

hello everybody, I have a quick question;

 

I wanted to render a piece of furniture with a white background ( no a white wall with different shades of white, but a totally white even background 255,255,255) so I went on 3D max and unchecked visible to camera. That works fine, but how do I let the background cast the shadows of the furniture.

I work with max and vray

 

PS: I didn,t understand my own question so attached is an example...

 

Thanks guys.

[Stephen Thomas]

You need to make the plane under your object into a matte object. In Vray to do this select your plane, right click and choose vray properties from the quad menu. Then check the 'Matte object' box, change alpha contribution to -1 and check 'Shadows' and 'Affect alpha' boxes. Your plane will now show shadows but render invisible.

 

Set your environment slot to white. If you have chrome in your model, you may want to add an HDRI to your environment override slot to give it something to reflect.

 

Here's a quick example.

[elada20]

Thank you Stephen, I will try. Just one question: Do you see how in my image you can't tell the difference between the white of the background and the withe oh the monitor, but in your image your background is actually grey... do you think there is a way to do that without photoshop?

 

Thank you for your reply.

[elada20]

To Stephen:

 

Another example, this rendering came out like this, I just made the room invisible to camera, and the white around is pure white, if i try your tecnique, I get close to what i need but not there yet....

[Stephen Thomas]

Thank you Stephen, I will try. Just one question: Do you see how in my image you can't tell the difference between the white of the background and the withe oh the monitor, but in your image your background is actually grey... do you think there is a way to do that without photoshop?

 

Thank you for your reply.

I see what you mean, rendered again this time unchecked 'affect background' in colour mapping options.

[Stephen Thomas]

To Stephen:

 

Another example, this rendering came out like this, I just made the room invisible to camera, and the white around is pure white, if i try your tecnique, I get close to what i need but not there yet....

Don't make the room invisible to camera, this will not give you the shadows. Just apply a vray material with white in the diffuse slot, then change the vray properties for the room as shown previously.

 

Should be fine.

[elada20]

ok, I took the 'affect background' away, but for some reason the back now is grey, we are good with the shadows thoug...

[Stephen Thomas]

Is your environment slot white?

[elada20]

yes, both, the one on vray and the default one and also reflection and refractions, I think that in your example you got withe because the direct light is strong enought, but in my case I have low lights not enought ti brighten the whole room, but that's just my teory... I long time ago I run in to a tutorial about this topic, and the guy was explaining how to do it with standard materials a opacity... but I can't find it anymore.... Thanks for your time...

[Stephen Thomas]

Not really sure what's going wrong. Here's my scene for you to have a look at. Even with the direct light turned off it still gives the effect you're after.

[elada20]

I really wanted to thank you for your time, hopefully one day I can help you. For some reason I can't open your file... is it max 8 or 9, I got the 8

[Stephen Thomas]

Sorry it's max 9. You can achieve the same effect using scanline renderer and standard materials too. Just apply a Matte/Shadow material to your ground plane. Then use either a direct light or skylight to illuminate your scene and get your shadows.

 

Here's the same scene done in scanline. Good luck!