rendering engine - quick questions .......

[bobtronic]

Hi claudio,

Make a compositing tag for the objects which cast
shadows. Then turn of "Seen by Camera". Now
you should see only the shadows.

hope this helps

Bob

[derwolpertinger]

another possibility is to render a multipass image with a shadow layer, that you can use in photoshop then.

[Claudio72]

I was on the right way bob when you answered


but......

I have an obj on the floor and I don't want to have the light on the scene
so what I did


a cube over a floor and a light source
compositing bg for the floor but I cannot turn off the "seen by camera"

I don't understand very well what does Compositing bg does.........why with the setting above I've a light grey floor?? I want a flat perfect white floor but if I don't understand how compositing bg works I cannot understand how to avoit this grey color



howewer the shadow is like I want...........

thank's to both

[STRAT]

one omni light with shadow, light brightness at 100%
copy it, turn off the shadow, set brightness to -100%

bingo bongo, no light, but a shadow.

[Claudio72]

what do you mean with "copy it"?

[STRAT]

exactly as i say - copy it. you need 2 lights.

[Claudio72]

maybe I looks like stupid but I don't understand what you mean
and what does it mean brightness to -100, looks like a workaround

[STRAT]

you need 2 lights, in exactly the same possition in 3d space, to cancel each other out. do this -

1) create an omin light, and possition it where you want to see the shadows eminating from.

2) make sure it has shadows turned on, and it's DETAILS tab has brightness set to 100%

3) goto EDIT > COPY. then EDIT > PASTE. this will duplicate the light in exactly the same place.

4) select the new light, switch off shadows and turn it's brightness down to -100% in the DETAILS tab.

there you go, a shadow being cast without a light source.

there must be other lights in the scene casting general lights too.

[Claudio72]

it doesn't work.........
if I turn the second light brightness to -100 and I leave the brightness on the general params to 100 all it's dark
if I turn the brightness of the general to 0 I still see the first light

[Claudio72]

don't worry STRAT, I would like to use the composite bg version, that I consider the clean way to follow

anyway, thank's very much

[STRAT]

thats why you need other general lights i the scene to light it generally.

[Claudio72]

yes, I've understood you example, but now I've got 100% what I want, with a little bit of luminance on the floor I've the perfect white I want

[STRAT]

no probs, glad you solved your problem :)

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