KeyShot Forum

Technical discussions => Lighting => Topic started by: Zvi on July 29, 2016, 08:09:37 am

Title: Eemphasize the shadow
Post by: Zvi on July 29, 2016, 08:09:37 am
How can I emphasize the shadow without Changing the brightness?
Title: Re: Eemphasize the shadow
Post by: Zvi on July 29, 2016, 08:40:10 am
I meant without changing the object look.
Title: Re: Eemphasize the shadow
Post by: Finema on July 29, 2016, 08:42:33 am
Hi Have you put a background ?
Title: Re: Eemphasize the shadow
Post by: Speedster on July 29, 2016, 08:42:47 am
What I do (I'm sure there are other ways) is to first render the beauty shot along with a clown pass.  I then swap the background for black, with no backplate.  Render again as a .png or TIFF, but with the Alpha Channel checked.  This will render the model and shadow only.  The purpose of using black is to avoid white or any other color from showing through the transparent areas of the shadow.

Then open the clown in Photoshop, then, using the "Place" command, drop in the beauty shot, then by the .png or TIFF.  IMMEDIATELY lock the layers!

You can now use the clown to select the model in the .png or TIFF and drop out the model, leaving only the shadow.  This will "double up" the shadow, and you can tweak the layer or change the transparency.  I often duplicate the shadow layer several times and tweak them until it's what I want.

Hope this helps!  I know others will pipe in with options...

Bill G
Title: Re: Eemphasize the shadow
Post by: Finema on July 29, 2016, 09:15:03 am
And you can add a pin in your environment
Title: Re: Eemphasize the shadow
Post by: bdesign on July 29, 2016, 06:10:42 pm
Here is a material graph node network that will allow quick adjustments to the look of your ground/contact shadows. You will need a ground plane in your scene. Connect a Color To Number node to the Unoccluded input of an Occlusion node. Connect another Color To Number node to the Occluded input. Connect the Occlusion node to the Shadow Color of your Ground Material. Use the "Output From" parameter of the Color To Number nodes to control the darkness/lightness of ground shadows (Unoccluded) and contact shadows (Occluded). For the default look of shadows, set both values to zero. To darken  ground shadows and/or contact shadows, set the "Output From" parameters to negative values. To lighten shadows, set the values to positive values. Setting the value to 1 will in essence turn the shadow off. You can further refine the look of shadows with the Radius and Falloff values of the Occlusion node. I've attached example renders of a few out of endless possible combinations. The "Output From" values for the Unoccluded (U) and Occluded (O) values are listed in the image titles. The last image shows the effect of setting the Unoccluded value to 1, with a negative Occluded value, and the Radius increased to 10.

Eric
Title: Re: Eemphasize the shadow
Post by: Zvi on July 30, 2016, 11:37:46 am
Hi Have you put a background ?
No.
Title: Re: Eemphasize the shadow
Post by: Zvi on July 30, 2016, 11:41:01 am
Here is a material graph node network that will allow quick adjustments to the look of your ground/contact shadows. You will need a ground plane in your scene. Connect a Color To Number node to the Unoccluded input of an Occlusion node. Connect another Color To Number node to the Occluded input. Connect the Occlusion node to the Shadow Color of your Ground Material. Use the "Output From" parameter of the Color To Number nodes to control the darkness/lightness of ground shadows (Unoccluded) and contact shadows (Occluded). For the default look of shadows, set both values to zero. To darken  ground shadows and/or contact shadows, set the "Output From" parameters to negative values. To lighten shadows, set the values to positive values. Setting the value to 1 will in essence turn the shadow off. You can further refine the look of shadows with the Radius and Falloff values of the Occlusion node. I've attached example renders of a few out of endless possible combinations. The "Output From" values for the Unoccluded (U) and Occluded (O) values are listed in the image titles. The last image shows the effect of setting the Unoccluded value to 1, with a negative Occluded value, and the Radius increased to 10.

Eric
Thanks Eric for the detailed answer. I really appreciate it.
Title: Re: Eemphasize the shadow
Post by: bdesign on July 30, 2016, 12:03:44 pm
You're welcome, Zvi. Hope it helps.

Eric
Title: Re: Eemphasize the shadow
Post by: Zvi on August 02, 2016, 02:43:38 pm
You're welcome, Zvi. Hope it helps.

Eric
Hi Eric
Can I use this method with a plane I added with my texture? There is no output of shadow in its node. (Its a new scene).