Gobo questions

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Gobo questions

Postby Builtdown » Sat Jan 20, 2024 11:27 am

Builtdown Sat Jan 20, 2024 11:27 am
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,
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Re: Gobo questions

Postby elsksa » Sat Jan 20, 2024 5:34 pm

elsksa Sat Jan 20, 2024 5:34 pm
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.
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Re: Gobo questions

Postby Lewis » Sun Jan 21, 2024 12:17 pm

Lewis Sun Jan 21, 2024 12:17 pm
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..
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Re: Gobo questions

Postby Builtdown » Mon Jan 22, 2024 9:03 am

Builtdown Mon Jan 22, 2024 9:03 am
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...
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question_Untitled-1.jpg
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Re: Gobo questions

Postby pxlntwrk » Mon Jan 22, 2024 10:30 am

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

Image
:::::::::::::::::
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Re: Gobo questions

Postby elsksa » Mon Jan 22, 2024 9:02 pm

elsksa Mon Jan 22, 2024 9:02 pm
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.
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Re: Gobo questions

Postby elsksa » Mon Jan 22, 2024 9:20 pm

elsksa Mon Jan 22, 2024 9:20 pm
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
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pixar-usd-kitchen-octane-daylight.jpg
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Re: Gobo questions

Postby Builtdown » Tue Jan 23, 2024 8:30 am

Builtdown Tue Jan 23, 2024 8:30 am
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?
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Re: Gobo questions

Postby elsksa » Tue Jan 23, 2024 4:03 pm

elsksa Tue Jan 23, 2024 4:03 pm
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
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Re: Gobo questions

Postby Builtdown » Wed Jan 24, 2024 8:21 am

Builtdown Wed Jan 24, 2024 8:21 am
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.
Attachments
Question_gobo_1.jpg
Question_gobo_2.jpg
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