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Gobo questions

PostPosted: Sat Jan 20, 2024 11:27 am
by Builtdown
Hi,

I have tried to learn new things lately. Next thing I would want to learn is using gobos.
I just saw one pic made with Octane that has a really nice gobo-shadows on the wall.

1. How to achieve those crisp and detailed shadows?
2. Should I use an area light with a gobo for the sun or should I use Environment:Daylight and block the sun with a Gobo-object?
3. Anything I do end up in really blurry shadows


Thanks for tips,

Re: Gobo questions

PostPosted: Sat Jan 20, 2024 5:34 pm
by elsksa
Blurry shadow is caused by some factors such as the distance of the light to that occluding object and the light intensity/scale.
Adjusting these aspects will yield the desired results

Regarding light filters, here's a page that details different methods.

Re: Gobo questions

PostPosted: Sun Jan 21, 2024 12:17 pm
by Lewis
Problem in LW Octane if you attach it to Light (item/light not geometry light) is that it has no UV map settings so projected image will be cut off in half, that thing never got fixed in LW plugin so it's very limiting and you would need to use geometry light with UV map to do some similar effect..

Re: Gobo questions

PostPosted: Mon Jan 22, 2024 9:03 am
by Builtdown
After testing I was able to produce a type of gobo I was after.
Not very good quality yet but at least I learned something.

In a quick scene test attached I used a HDRI as a diffuse light and I added a "spotlight" with a gobo to get detailed sun/shadows on the wall.

I would love to do this with just a Environment:Daylight but I don´t think it´s possible...

Re: Gobo questions

PostPosted: Mon Jan 22, 2024 10:30 am
by pxlntwrk
Hi ,
have you tried putting the gobo in an Octane light in "perspective" projection?

Image

Re: Gobo questions

PostPosted: Mon Jan 22, 2024 9:02 pm
by elsksa
Builtdown wrote:I would love to do this with just a Environment:Daylight but I don´t think it´s possible...

It is. All the pointers are in my previous message.

Re: Gobo questions

PostPosted: Mon Jan 22, 2024 9:20 pm
by elsksa
Quick setup to demonstrate, mesh window (no gobo/cookie textures or mesh)
Left has a sun scale at 2 and right at 1. Higher values and optionally sky turbidity results in a softer lighting.
Image

Re: Gobo questions

PostPosted: Tue Jan 23, 2024 8:30 am
by Builtdown
Elkska,

1. But can you put a gobo texture (ie. a tree) to the Sunlight?
(Like it was in the first attached interior picture.)

2. Or have to just block the sunlight with some gobo-object?

Re: Gobo questions

PostPosted: Tue Jan 23, 2024 4:03 pm
by elsksa
Why wouldn't it be possible?
Once again, it is following the same logic and physics as the reality.

Soft vs Hard shadow from which the occluding object (e.g. gobo) will be "projected" accordingly, either with a blurry shadow or sharp depending on the lighting scale, distance and intensity.

Image

Re: Gobo questions

PostPosted: Wed Jan 24, 2024 8:21 am
by Builtdown
Hi,
Thanks for responding.
I know that smaller light creates sharper shadows. But my question was more about the following:

I attached two pics.
Can I add gobo texture somehow to just the Daylight sun without needing to add any "sun blocking" object to the scene?
So the sun light would be "blocked" even when I move the sun.