Author Topic: Need help with the shadows ?!?!  (Read 1415 times)

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Offline stefan marji

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Need help with the shadows ?!?!
« on: September 21, 2018, 11:14:30 pm »
Hi there. I need to maintain the shadow as it is ( there is no ground plane , just keyshot basic shadow ) that works fine.
But I have issue to cut the shadow into the scene ( to blend into white before the boundaries of image )
I have tried with ground plane or other kind of planes with adding opacity - transparency map - that cuts the shadow , but that shadow is nowhere near the original one without ground shadow .
I need this for animation there fore all post-processing suggestions are off the topic , I need this inside keyshot.
Someone help ?????

Offline Weezer

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Re: Need help with the shadows ?!?!
« Reply #1 on: September 22, 2018, 07:58:15 am »
You either need to change the lighting, or fake it in post. A quick bit of masking/feathering (in After Effects or similar) would do the job.

Offline TGS808

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Re: Need help with the shadows ?!?!
« Reply #2 on: September 22, 2018, 11:55:16 am »
If you need to keep it inside KS, check the Occlusion Ground Shadow box (under Ground Shadow). They are not really as nice as the standard ground shadow but they shouldn't bleed to the boundaries of the image. That's probably the best you're going to do if you don't want to do any post processing.
« Last Edit: September 23, 2018, 02:19:44 pm by TGS808 »

Offline RRIS

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Re: Need help with the shadows ?!?!
« Reply #3 on: September 23, 2018, 09:36:24 am »
Yeah I would say go for occlusion ground shadows and change the shadow color from black to something a little lighter if it's too heavy.
Upping shadow quality will usually give you tighter shadows, but for animation it would probably boost render times too high.

Finally you could consider photoshopping a shadow, putting it as opacity map on a plane underneath the chair and disabling ground shadows. That way you have complete control over the shadow.

Offline MWo

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Re: Need help with the shadows ?!?!
« Reply #4 on: September 23, 2018, 09:01:45 pm »
That solution isn’t that complicated and discussed in several posts.
You need two things:
First a ground plane
Second a color fade texture (circles) from black to white in the opacity channel of the ground plane to define its boundary.
You can also use an occlusion texture to define opacity, but I think that in this case it wouldn’t work so well.

Good luck!

Hope that helps
Cheers
Marco

Offline stefan marji

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Re: Need help with the shadows ?!?!
« Reply #5 on: September 23, 2018, 10:12:04 pm »
Thanks to everyone that jumped to help.
As you MWo suggested I have managed to solve the problem with ground plane.
I have pulled ground plane up and made opacity hole on it ( outside its flat white and in the center is visibility 0) , so it will show central area of key shot floor only .
Once again thank you everybody for quick support !

Offline DriesV

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Re: Need help with the shadows ?!?!
« Reply #6 on: September 24, 2018, 05:06:21 am »
I am glad you found a solution.

For what it's worth, here is a trick I use a lot when doing these sort of ground shadows...
I often apply an Emissive Layer to a Ground material. I then set the Ground material's Shadow color to white, set the Emissive Color to black or dark grey, and use an Occlusion texture (Occluded: white; Unoccluded: black) as an Opacity map for the Emissive Label.
The nice thing about this approach is that the Radius slider of the Occlusion texture allows to precisely control the extent of the Emissive "shadow".
A drawback with this method is that the shadow is based on occlusion and will thus not change depending on lighting, should that be desired.

I attached a sample scene. The model comes from Dimensiva.

Dries
« Last Edit: September 24, 2018, 01:01:44 pm by DriesV »

Offline MWo

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Re: Need help with the shadows ?!?!
« Reply #7 on: September 24, 2018, 07:40:22 am »
Chapeau Dries.

Great solution. Thx for sharing!


Cheers
Marco

Offline stefan marji

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Re: Need help with the shadows ?!?!
« Reply #8 on: October 21, 2018, 10:14:12 pm »
I am glad you found a solution.

For what it's worth, here is a trick I use a lot when doing these sort of ground shadows...
I often apply an Emissive Layer to a Ground material. I then set the Ground material's Shadow color to white, set the Emissive Color to black or dark grey, and use an Occlusion texture (Occluded: white; Unoccluded: black) as an Opacity map for the Emissive Label.
The nice thing about this approach is that the Radius slider of the Occlusion texture allows to precisely control the extent of the Emissive "shadow".
A drawback with this method is that the shadow is based on occlusion and will thus not change depending on lighting, should that be desired.

I attached a sample scene. The model comes from Dimensiva.

Dries
@DriesV this is ultimately best solution with best results!!! THANK YOU SOO MUCH FOR SHARING THIS APPROACH!!!

Online Esben Oxholm

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Re: Need help with the shadows ?!?!
« Reply #9 on: October 23, 2018, 06:35:38 am »
Hi Dries. Cool approach.
Do the emissive material have any advantages over using a 'flat' material type instead in the same way?