[seghier]

Hello , render scene than shadow for compositing take long time
i tried to render car but enabling of shadow for each material in the scene need more works
i hope you add enable shadow to group ( objects group or material group )
and possibility to disable shadow of the objects ; that save time and easy for compositing

[Mihai]

But you don't need to enable shadow for all those different materials, if what you need is the shadow that falls on the ground....
In that case you only need to enable shadow for the material applied to the ground. Turning on Shadow in the material will make that material act as a "shadow catcher".

[seghier]

thanks Mihai
yes i always use this method but it take long time : render the objects than render full shadow to get the right result
yesterday i tried to render car; to save time i enable shadow for all materials of cars and plane , i enable shadow pass and alpha and save the result as exr ( we don't need rerender the same scene two times)
in photoshop i move the shadow layer above the render layer ( to avoid errors of shadow and it work like ambient occlusion)
the problem here that the car already have shadow , for this reason i post this wish

[seghier]

[Mihai]

to save time i enable shadow for all materials of cars and plane

This is what I said in my previous message: you don't need to enable the shadow option for all materials.....
Just enable it for the ground.
Forget about "ambient occlusion" pass, it will simply make your render look like crap. And, since you've enabled shadow to be calculated in a separate pass for ALL your materials, it will also take longer than simply rendering a shadow pass for the ground plane.

Read this page:
http://support.nextlimit.com/display/mx ... ow+channel

Especially the paragraph: "Rendering diffuse, alpha and shadow pass at the same time"

[seghier]

thanks , can maxwell render diffuse, alpha and " full shadow pass" at the same time ?
if it is not full shadow it make problem with compositing : Knocked out shadow pass vs Full shadow pass

[Mihai]

Not it's not possible to render a "Full shadow pass" at the same time as the main render, but on the other hand it may not always be necessary.

[seghier]

for this reason i use shadow of all object
it necessary for animation and big view
i tried iray and the result saved with shadow and transpancy ( better than keyshot for example)
i wait when maxwell add this feature

[Mihai]

for this reason i use shadow of all object

But I don't understand, how does using a shadow pass on all the objects of the car, solve the issue that the "full shadow pass" is trying to solve, ie you may see a white outline where the cars tires touches the ground?

[Mihai]

I think you misunderstand this phrase form that docs page regarding how to render a "full shadow pass":

The solution is to render a separate shadow pass with full shadows simply by hiding to camera all the objects in the scene and rendering only the shadow channel

This does NOT mean: turn on shadows for all materials in the scene. I am still only interested in getting a shadow pass for the ground only. I don't want a shadow pass for all the objects in my scene. Thus, I only turn on shadow for the material that's applied to the ground.

[seghier]

i worked with full shadow pass projeted in the ground many times (all objects are hidden from camera)
but this method need to render objects with alpha
than render the full shadow on the ground
that take long time
i want one render without modify the scene and to get what i need for compositing . rerendering is not a good choice
; rendering shadow of all objects solve that and avoid the white outline but the problem the objects already have shadow

[Mihai]

rendering shadow of all objects solve that and avoid the white outline

How does it solve it?