A tip about transparency shadow problems

[Zay]

Was playing around with the new plugin when I had the known transparency problem when two object are very close to each other. This can happen with hair, pockets on pants, shirts,jackets or when you want to hide some stuff. Normally you can change the Rayepsilon slider to fix this, but this can also create unwanted side effects like bad shadows from low geometry objects.

In this scene I have a shadow problem with the hair line. Many ways to go about that, but I use my favorite fix which is fast and that is to scale the scene. Under Setup I changed the scale from 2.6 to 10. This is just a quick fix I hope you can use if you run into this problem in the future.

Hair line casting a shadow.

Scene scaled to 10 to fix it.

[bpzen]

thanks, dumb question what are you changing the scale of the hair?

[Zay]

Use the scale setting within the Poser plugin. It scales the entire scene.

Click the Setup button to get to the configuration window.

setup.PNG (9.98 KiB) Viewed 3670 times

[bpzen]

I gave this a try but it really messes up lighting, is there a way to set this and have the lighting in octane scale appropriately or do we need to re do lighting too?

[morphious2013]

I guess I need stronger glasses. I honestly see no different in pics.

[Krew]

I guess I need stronger glasses. I honestly see no different in pics.

I couldn't either until I opened both pictures in separate tabs and switched back and forth. In the first picture, look at the thin black line above the left (screen left) eyebrow and just under the widow's peak of the hair. I think those are the shadows talked about. In the second picture those are gone.

[Zay]

As Krew mentioned there's black lines from the hair cap. It's a transparency issue you can run into now and then.

I gave this a try but it really messes up lighting, is there a way to set this and have the lighting in octane scale appropriately or do we need to re do lighting too?

Area and IES lights can change as the distance will be longer. HDRI doesn't (not that I have seen). So I would just fix it in photoshop if there's too much work to try and fix it with the scale option. I usually have a higher scale option from the start now when setting up scenes to prevent this from happening in the first place.

In the standalone I also use decameters as default as it helps to fix those things. But not always.

[Zay]

Here is a better example. Here I have hidden the pockets by setting the pockets opacity to 0. Notice the black shadows. But this problem only happens when 2 geometries are very close to each other.
So if you see things like this you know what to do. Either scale the scene or try to pull the surfaces away from each other. That also goes for the hair. Maybe the morphtool can pull it out so you don't need to adjust the scale. But that properly wouldn't work on the pockets.