Translucent Concrete Material

[Torsten]

So it has been a while since this topic was last replied on. I have made some new steps in creating a material. And it seems to do a fairly good job now. The geometry consits of blocks with the facing faces the semi translucent material, the sides of the blocks are not translucent. The material look really close to what it actually looks like. The only problem left is that there are still shadows visible on the ground. This does not happen in real life.

Does anybody have an idea how to eliminate these direct light/shadows? I know Vray has an option per material to turn off "cast shadows".

[maru]

What is the desired effect about the shadows here? Do you have a real life reference?
If you disable shadows, the objects will not block light at all - are you sure you would like that? Here is a guide on disabling shadows: https://coronarenderer.freshdesk.com/support/solutions/articles/5000516723
You can also use the same technique (rayswitch) to make the material solid - simply put a different, solid material in the GI slot.

[Torsten]

Attached a real life example. As you can see, light flows trough the concrete, the lighting is diffuse. But the block itself blocks the direct sunlight, casting a shadow on the ground. In vray i have created a similair effect using the option "cast shadow" in material settings. If i use the rayswitcher as you suggested, there is no light coming through the blocks.

I need the direct light to be disbled. So the blocks shadows are completely intact.

Thanks!

[maru]

I think you need to put any solid material in the GI slot of the rayswitch mtl. :)

[PROH]

Hi. How about putting an extra plane on the inside (inside the room) that's invisible to the camera but still cast shadow? If this makes the shadow to dark, then it could also emit a soft subtle light?

Haven't tried it - just an idea...

[Torsten]

I tried to use de Rayswitch material, putting a solid material into the Global Illumination slot, and the translucent materials in the other slots. But this disables the translucency of the material, so the render becomes black.

[PROH]

Hi tmiddelkoop. I just did a quick test, and think I got a solution. Put a plane inside your wall and give a CoronaLightMtl with these settings:

Intensity: 0,0
"Emit light" on
"Emit light on both sides" on
"Occlude other lights" on
"Visible directly" off
"Visible in reflections" off
"Visible in refractions" off

No need for RaySwitcher or unchecking stuff in object properties.

I've attached two pics of this in action. The wall on the left is without this plane, and the wall on the right is with. I've also attached a pic og the LightMtl setup.

BTW - If you need to let a little light in, then you can use the oppasity slot in the LightMtl to make the shadow les dense. I tried this using a Corona Color map set to RGB 210.

Check it out :)

[Torsten]

Wow Proh, i really like your result, the concrete also looks very nice! The idea of your setup works pretty well. The only thing is that there is nog light coming through the wall if you putt your fake light into the setup, atleast in my try. And if you use the color opacity slot, the shadows become visible again. I also tried using you setup combined with fake arealights in front of the wall. But the richness of the material is lost in this setup.

If you put your setup in a closed box, is there light coming trhough the concrete into the room?

Not sure if there is a final solution in the options attached in the images.

[Torsten]

Proh, would you mind sharing your scene? Or maybe the concrete material?

Thanks!

[PROH]

I haven't got access to it right now, but it's very basic: Its a multi/sub-object material with ID#1 being Concrete (from "Corona Basic Set") for the box sides, and ID#2 being a Concrete/Fiber blend-material for the box front and back. As blend mask I used a Cellular map.

Regarding the "shadow-caster" I did try another way, that might let some subtle light inside (depending on your scene and the way your fiber material is build): Instead of one big vertical plane you can use a series of smaller horizontal planes placed above each other with a "building block size" between them. This will simulate the top and bottom of the building blocks in real life, and will block sun-rays from shining thru the wall, but allow horizontal light to pass.

I think the problem is, that unless you're building these walls exactly like in real life, you'll never get it 100% right. But maybe 98% could do?

Keep it up :)

[PROH]

OK. Did some more testing, and did find a way to get light without shadows. It's actually quite simple. I've uploaded 2 pictures:

Test2-2a uses same material setup as the pictures from my previous post - exept for the IOR in the Fiber material being a little higher.

Test2-2b has some changes in the CoronaLight Mtl. "Emit on both sides" is turned off, "Directionality" is set to 0,4 and the light is turned on with "Intensity" set to 80.

I don't know how much light comes thru these bricks in real life. From your photos it doesn't look like much, but by adjusting the directionality and intensity it's possible to create something that doesn't look to "fake". It will take longer to render tho.

I've also attached the scene (max2014, Corona 1.4 daily 2016-01-27).

[Torsten]

Thank you so much for your help!

[Jellehe]

Can anyone convert this material to v-ray vrmat for me?

[maru]

Any volunteers?

[romullus]

Seems pointless to me - Corona renders much better with its own materials :]