Hello all, I’m still re-learning Blender at the moment, but one thing I can’t figure out is how to make something reflect light.
Here is an example, POLICE VEHICLES!
Police vehicles and emergency vehicles have reflective vinyl. At night when light hits this material it gives the illusion the vinyl is glowing. Same thing with traffic signs.
What I am attempting.
I want to have the ability to send a proof to a client with their vehicle decals on a 3D model. However, when there are reflective decals I need a way to show them “glow”.
I’m having the camera rotate around the object and the lighting goes from day time to night, and as the camera rotates the object I need the decal(artwork) to illuminate as if it was a reflective vinyl. Preferably depending on the direction of the light source which will be from the camera angle to object.
What I have done so far.
The only way I have managed something close is with the “glow?” in Blender. But this illuminates the overall decal and I would like to create the proper effect. The glow distorts the actual colors of the decal and that is something that will surely confuse the clients.
I’m texturing with UV’s if that makes any difference.
I’ve scoured every source I can find in regards to Blender tutorials, but nothing quite pin points exactly what I am doing.
Any help or suggestions would be greatly appreciated!
Thank you.
I don’t know anything about “reflective vinyl” - for me vinyl is something completely different entirely
Traffic signs are not your typical reflective. Instead they are retro reflective, meaning they reflect light back in the direction light came from - like a cars headlights.
For retro reflective properties, you can try a glossy node with a bit of roughness, using geometry/incoming as the normal.
Search the forum for retro reflective, I’m sure it’s been discussed before. Otherwise, provide an example file.
Well there is the key word I didn’t consider!
Retro-Reflective!
Honestly I’ve never called it that, it’s always been reflective vinyl for any project I’ve designed, created, and installed.
However now that I’ve looked through the spec sheets for 780mc reflective vinyl, I do see a mention of the retroreflective coefficient. If I bothered to read my spec sheets for my material I probably would of figured this out faster!
However with that being said, a 10 second search on Google brought me directly to my answer on the first link. Thank you CarlG for knowing the keyword.
Oh BTW in case anyone wants this information here is the link!
AND another link
I would like to note I have not tried any of this out at the moment!
First, welcome back.
Retro-reflective (RRfl) materials are quite easy to do in CG, just by changing the surface normal to the be the same as the incoming ray (on a glossy shader), just like CarlG said.
But depending on the type of RRfl material, you might need to tweak this simple N = I…
Some RRfl surfaces are not ‘isotropic’ (typical slightly rough glossy with N=I), and reflect more radiance from/to specific directions (anisotropic and dephased structures), and sometimes they even produce wavelength interference, causing some iridescence that is hard to reproduce.
For a simple road sign, or some fireman suit, the first option works great. For other phenomena, it might be insufficient.
I won’t know for sure how everything turns out until I get off of work later.
The texture part I haven’t messed around with to much as of yet. From my memory to what it is now, it has changed quite a bit!
The real test will be getting only specific artwork in the UV to reflect and not the rest.
But if I can fine tune it I would be overjoyed!
If you already have some textures, you can reuse one of them (the one where the RRfl parts are more pronounced), make a mask and use it to mix your shaders…
Otherwise, if the mesh has a topology that follows those areas, you can add a RRfl material just to that part of the mesh…
There’re even more options on the table.
I wasn’t able to get the effect on the same object. No matter how I set up the artwork the entire piece would glow in some manner, or I would lose detail in the black.
But the way I fixed it was by duplicating the side of the vehicle and then adding the UVtexture to the duplicated object letting the Alpha hide what I don’t need; while leaving the vehicles overall texture/color unaffected and easily changable.
I’ll upload the nodes for the “glow” when I get a chance.
I’ve also added on here a link to a quick and dirty animation. You can see the difference between the two sides, and also be able to note how the glow on the reflective side travels along the art in the dark.
From personal experience using material like this in my field, this is the closest representation to how the material reacts. The only thing I wish I could of done was make the shine more pronounced but for the time being I’m satisfied.
*Please note that the vehicle model is not mine. I pulled it from the internet so I had something I can use this on.
The main concept of retro-reflective materials is that they reflect light in the direction the light comes in.
That means that with different surface normals, you still get something based on the camera direction, and not ‘really’ based on the surface normal…
So simply fake the surface normal as the incoming vector (from wherever the ray comes), we say that the surface will ‘act’ to x% of the ligth (by mixing other shaders) by reflecting the ligth coming from the direction of the ‘viewer’ (as if every point in the surface is a tiny mirror pointing at the ‘camera’):
Also note that the way you’ve setup your shot doesn’t really “work” to test out retro reflectiveness.
Try setting up your camera and light from an angle instead of face on. Imagine looking at a reflective lake from the shore. Normally you’d see the sky and other side reflected in the water. If the water was retroreflective, you’d see yourself no matter what angle you observed it from.
