Translucent materials and light baking

[juoolz]

Just wondering what the solution to this is.

I have a translucent lampshade. Before the light bake you can clearly see the pattern detail (see attached)

Once baked it looks like this…

What do I need to do to maintain the detail and illusion of light making it through the surface.

Cheers again in advance

J

[Lovecraft_K]

Hey juoolz -

Can you post a screenshot of your lampshade’s material setup for me to look at?

Thank You

Eric Ketchum

[juoolz]

Hi Eric. Please find material attached

Cheers J

[Lovecraft_K]

Hey J -

A couple of lighting setup questions from your level, do you have a pointlight or spotlight inside of your mesh in the level itself? If it’s a spotlight increase the source radius to include the Lamp shade itself. I am not certain exactly how you mesh is set up just from the pictures but you could try to switch the lampshade material to two sided but unless your shade is just a plane wouldn’t cause the look that you are seeing in result. Finally do you have any post process settings applied to your level. I was able to recreate you material internal in 4.5.1 and it rebuilt just fine.

Let me know and we will continue to try to track down a solution -

Eric Ketchum

[juoolz]

Hi Eric thanks again for your time.

Okay the issue I was having (or limitations) appeared to be due to the way my mesh was setup and some of the light settings. (See image 1)

Due to the mesh having two sides where the light was passing through it caused some form of shadowing that was giving that solid matt look seen in the previous post.

Using this mesh I was able to get a relatively good result by removing “cast static shadows” and setting the light to “Stationary” on ether the mesh or the light. You can see the result in the image below on the right.

NOTE: Setting the light to “Static” did NOT work.

This obviously was not the ideal result. As you see compared to the left image.

I then re-worked the mesh removing the outer layer and keeping the normals facing inward.

Then in the materials editor I set the material to “two Sided”. After the bake this gave me the desired result including the correct shadowing.

Again I had to set the light to “stationary”. Whenever using “Static” the bake resulted in the image below.

This might be an obvious question however I was under the impression that “Static” and “Stationary” lights would create the same lighting after a bake, with the difference being dynamic shadows from stationary lighting.

Finally I’m using a Mac and Engine 4.5.1

Cheers again

J

[juoolz]

Hi Eric. I actually posted a HUGE response to this but I must never have actually posted it

Anyway in short my mesh lampshade had two sides. Whenever I baked the light it would appear matt…as if the lighting/shadow data on the outside was counteracting the light shining through. (Note: I did get quite a good look turning “cast shadow” off ether on the light or the object. This however dose have aesthetic limitations.)
I then rebuilt the mesh so that it only had one side with the normals facing in towards the light. I altered the material to two sided and then baked again and…still didn’t work… it was a bit better but was creating poor lighting. I was determined not to give in so I eventually discovered that the result I was looking for only worked when the light was set to “Stationary or Movable”. You can see the results in the attached image (light types in order).

I have a couple of questions to the result:

1. I was under the impression that the light baked from static and stationary was the same with the major difference that stationary cast dynamic shadows.
2. Is this possibly a Mac limitation (And I know I really need to dump the mac…its the next thing on the list
3. If its not just a mac limitation. Do you have any suggestions how to deal with say a semi translucent surfaces like skin or Ice. were its still desirable to have two sides and have them also receive shadows.

Thanks again Eric always appreciated.
J

[Lovecraft_K]

Hey J -

Believe it or not I did see your post in my email before it went away I don’t know here so I do have some reference to what you are saying. So let me break these all down for you:

1. Static Lighting only exists as Shadows and Lighting information baked onto a Static Texture (hence the name). Stationary Lighting works similarly in that the information is baked to a static texture but if within the range of the light it actually is emitting light dynamically just like a movable light.

2 & 3. This is not a limitation of a Mac, so you can hold off buying a PC immediately. The Subsurface Shader will only work with a Stationary and Movable Light. You biggest problem is actually unfortunately a limitation of the engine with how we deal with translucency at the moment. As far as a possible work around which I actually just had some success with recently with this exact look:

Go back to the two sides mesh, but take the exterior polygons and the interior polygons a separate material. Then in UE4, make a material that is opaque (so we are avoiding the issue of the translucency altogether) and take the logic and texture that would go to your sub surface color and pass it into the emissive channel. Some key things to look out for in this, make sure you are clamping to 1, unless you are dealing with the interior or underside in which case you can let it get a little bit of the emissive flare. Also you may want to play with multiplying the logic before its inputed into emissive to control brightness and if you need to add a power node to help control the contrast.

Hopefully that gets you started but let me know -

Thank You

Eric Ketchum

[juoolz]

Thats awesome thanks. Ill be adding quite a view assets in the next couple of weeks that have translucent properties and post the results here should anyone be interested.

Cheers again J