Home Forums Challenges Challenge 03: Retroreflector

67 replies, 22 voices Last updated by Profile photo of fred_lc fred_lc 5 months, 3 weeks ago
Viewing 20 posts - 41 through 60 (of 68 total)
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  • #3060 Score: 1
    Profile photo of Arvid Schneider
    Arvid Schneider
    Participant
    • Sn. Lighting TD ILM
    11 pts
    @arvid

     

    I found some time today to work on my shader approach..I was trying different patterns to get a proper reflection back. I have ended up with a torus shape which drives the normal slot. I have added different shaders together (and break physicality ) to achieve the reflecting light effect. ( would be great to have a bxdf which would support retroreflective surfaces, especially for animale eyes, like cats ). I used thin film ( though I think the real effect should be diffraction) to get a little color variation, which is driven by a graded normal map, so it only appears from where the light is reflecting back. And then some shading for the cone which is sss, dust, paint and specr breakup.

    Front and side

    Front

    This post has received 1 vote up.
    #3069 Score: 2
    Profile photo of Anthony Pilon
    Anthony Pilon
    Participant
    • 3D Generalist
    20 pts
    @anthonypilon

    Had some time to work on this more — today I focused mostly on adding the multiple reflection bands. I didn’t understand what was causing them in the reference images, until I realized that retroreflected light from the grazing angles of the cone still had to travel through the clear coat layer on its way back to the camera, and that could possibly cause additional highlight bands.

    Some additional renders with maps from HDRI Haven:

    To get the left and right bands, I used two more copies of my anisotropic dispersion setup, rotated +-45° on vertical axis. To overcome the black artifacts, I add the two together, since with 90° of difference they don’t overlap. Then I blend them in with the original dispersion shader, but only on grazing angles.

    (Vector and Texture outputs rotate in opposite directions. S_GlossyDispersion is the same setup I was using before, but grouped together so I can make instances easily.)

    I have no idea if this way of doing it is appropriately imitating what’s actually going on in the real material, but it does approximate the look, and I at least tried not to break physicality too badly.

    This post has received 2 votes up.
    #3070 Score: 1
    Profile photo of Zeno Pelgrims
    Zeno Pelgrims
    Keymaster
    • Probably waiting for uncompleted render buckets
    27 pts
    @admin

    Dude! Sick! I’m learning so much from your posts.

    This post has received 1 vote up.
    #3074 Score: 0
    Profile photo of Mohammed Hamid
    Mohammed Hamid
    Participant
    • Freelance Look Development Artist
    3 pts
    @herc98

    Does anyone know how to approach @anthonypilon dispersion technique on VRay? I tried using samplerInfo with the extra VRay attributes but I’m having trouble.

    #3111 Score: 1
    Profile photo of Gobgob
    Gobgob
    Participant
    • 3D generalist
    1 pt
    @gobgob

    @herc98 I tried at work using @anthonypilon dispersion technique on VRay, here is what I came up with :

    I’ve used  the samplerInfo node with the extra VRay attributes, the BaseMTL has no reflections. hope that helps!

     

    This post has received 1 vote up.
    #3114 Score: 0
    Profile photo of Mohammed Hamid
    Mohammed Hamid
    Participant
    • Freelance Look Development Artist
    3 pts
    @herc98

    @gobgob

    plusMinusAvg was the node I was looking for! Thanks man.

    #3116 Score: 0
    Profile photo of Oleksii Kovalevskyi
    Oleksii Kovalevskyi
    Participant
    • Graphics programmer
    @alkova06

    Hi, guys!

    I use Unreal Engine again) I used clear coat technique for creating a surface with bottom normal and fake dispersion. If anybody wants, I can make build and you can look it in real time.

    Main

    Material part1Material part2

    #3127 Score: 0
    Profile photo of eric
    eric
    Participant
    • architect
    1 pt
    @ericnixon

    Hello all, I did a little test using maxwell. The idea is to create a retro-reflective effect using sss with a directional bias to the scattering, so that it only scatters backwards, i used a value of 0.8 with zero roughness and low attenuation on a 2mm volume geometry.

    I also hacked the C4D geometry normals slightly with a 20% bias towards camera, and rendered the correct specular gloss, on a slightly enlarged copy of the object, with the undistorted normals.  < it is a subtle tweak , you can ignore this hack.

    test

     

    These are 30 sec renders, just to test the angle of the ‘flash’, sorry they are low quality.

    #3144 Score: 0
    Profile photo of eric
    eric
    Participant
    • architect
    1 pt
    @ericnixon

    I tried to render this in trickier real-world lighting, without the normals hack, and the material is very inefficient, although it might be suitable for flat surfaces like a road sign.

    sss

     

    For a still render the normal hack is more promising but somewhat fiddly… in C4D the plugin vertex normal tool is also needed for that.

    #3189 Score: 0
    Profile photo of eric
    eric
    Participant
    • architect
    1 pt
    @ericnixon

    Here is a decent result using the normals 85% towards camera. (works well if there is a strong light-source behind the camera). I cant see how to automate the normals for animation, so using this technique for animations would require a manual intervention frame by frame 🙁

    85% normals bias

     

    This renders fast.

    I duplicated the geometry to create an upper surface, a bumpy mirror, which is only 20% visible, this generates the retroreflective effect, I also added a maxwell tag to make the backfaces of the polygons invisible (probably helps).

    #3203 Score: 0
    Profile photo of Andre Chaves
    Andre Chaves
    Participant
    • Visual Designer
    @andrefchaves

    Hello all, newbie here, any thoughts on how to achieve @anthonypilon technique on Arnold for C4D? 🙂

    I think I got the retroreflective effect to work but still working on everything else

     

    Retroreflective effect

     

    Edit: I’ve done an animation test https://vimeo.com/218192578

    #3229 Score: 1
    Profile photo of eric
    eric
    Participant
    • architect
    1 pt
    @ericnixon

    Andre its looking good, but in the animation the highlights position is static?

    I wanted to post this geometry test, The dimensions (the depth) is a guess, the shape used is a cube. Render time is fine, as long as I use roughness zero, for both materials.

    The polycount is about 15000 quads, because I only have to model the intersection and then tell maxwell they are nested dielectric (inersecting transparent volumes) to do this you need to make the mirrored material notionally transparent (1nm attenuation)

    geo

    disc

    EDIT:  ‘everyday use’ rough mirrored version, low-poly without dispersion, also without nested dielectric, I was wrong about that, just intersecting volumes is fine.

     

    This post has received 1 vote up.
    #3341 Score: 0
    Profile photo of fred_lc
    fred_lc
    Participant
    • 3D Generalist
    1 pt
    @fredlacocca

    This is an awesome and addictive challenge.Learning a lot of it.

    A redshift version of the BSDF approach. It was a bit of a headache due to the linear or not linear nature of the nodes.
    I’m Using the @anthonypilon ‘s dispersion technique and using it also fot the two reflection lines
    Thanks to @anthonypillon for sharing these

    I realize that the two retroflection line are too large. and probably not all time present. In the video their behavior is not so obvious.

    Next step is to improve this and add dirt, small details etc.

    Animated version here (vimeo)

     

     

     

    #3520 Score: 0
    Profile photo of Leif Pedersen
    Leif Pedersen
    Participant
    • CG Generalist
    @leif3d

    This looks like so much fun. The entries and R&D are really great.
    I wish I wasn’t so busy!

    #3603 Score: 4
    Profile photo of Anthony Pilon
    Anthony Pilon
    Participant
    • 3D Generalist
    20 pts
    @anthonypilon

    Here’s my final version:

    Competition light setup

    Evening with headlight

    Morning

    And here’s an animation of the first two. Rendered 40 frames for each overnight, then time-remapped in AE. Render times continued to be pretty good, with the full 1920 x 1920 renders taking less than 20min each on my GTX 660.

    All the renders and node setups are in one place over at my Artstation. I had a lot of fun and learned a few new tricks on this challenge, even though this one got less traffic (heh) than the others.

    This post has received 4 votes up.
    #3606 Score: 0
    Profile photo of fred_lc
    fred_lc
    Participant
    • 3D Generalist
    1 pt
    @fredlacocca

    @anthonnypilon
    Really amazing and creative work.
    But looking at your artstation page I realized I’ve not really understood your set-up.

    And also realized my set-up is slightly different and not a correct redshift version of yours. I calculate the angle between the incoming ray and the light. Using the resulting value to drive gloss & reflection level.
    Obviously this work only with one light. Not really a real world approach. It’s more a “fake”.

    is your “geometry” node, the blender equivalent of the sampler info node in maya or the state node in redshift ?

    #3635 Score: 0
    Profile photo of James
    James
    Participant
    • 3D Generalist - Axis Animation
    @jameshodgart

    Awesome stuff guys, looking forward to jumping in on this next month with Houdini & Mantra 😀

    #3639 Score: 0
    Profile photo of Andre Chaves
    Andre Chaves
    Participant
    • Visual Designer
    @andrefchaves

    So, here is my final shader & render

    Final render

    Nodes

    aaaand an animated version

    Definitely could be better, I did not manage to achieve the chromatic aberration on the specs 🙁
    Initially I tried to solve the retroreflector material using only one alSurface shader but in the end had to add another just for some extra speculars..
    I created a dirt material that should be something between mud and paint (that ended up looking more like blood and other stuff haha)

    My final setup consisted of:
    5 Materials:
    3 Base Materials: Retroreflector, Cone and Dirt; 2 Mix Materials: Retroreflector Mix and Cone Mix (The retroreflector material mixed with dirt material, and the cone material also mixed with dirt);
    Doing some tweaks inside the Mix materials is possible to apply them to a variety of other objects procedurally
    It was an excellent exercise to understand a little bit better the process behind creating more complex shaders 🙂

    #3646 Score: 0
    Profile photo of eric
    eric
    Participant
    • architect
    1 pt
    @ericnixon

    I don’t think anyone has mentioned yet that retroreflections are effectively 180 rotated reflections due to the doubled reflections/refractions. Therefore the shimmering highlight is actually moving left as the light source is moving right. You can see in the reference photos that the chromatic highlights occur on the opposite side to the lightsources position for the same reason.

    Is it possible to code such behaviour into a shader? or is modelling the surface the only way… anyhow it was good to try, I think we all learnt something. Looking forward to the next challenge.

     

    #3675 Score: 0
    Profile photo of Zeno Pelgrims
    Zeno Pelgrims
    Keymaster
    • Probably waiting for uncompleted render buckets
    27 pts
    @admin

    Right, I didn’t expect to have this little time this month! Racing against the clock here to get this in on time, haha.

     

    Here’s my entry, super heavily inspired by the work of @anthonypilon. I will post a breakdown at some point, including a video which really shows it off. I decided to go for an approach which tweaks the normals of the flakes to the camera position, instead of trying with geometry. Using geometry, the effect was really simple to get but when trying to wrap that geo around the model, the cubes got skewed too much and they lost their retroreflective property. I couldn’t see a way around this, so bsdf approach it was.

     

    There’s plenty wrong with my try, but I can’t exaggerate how much I learned with this one.

     

    For now, here’s my final images. Arnold as usual.

     

    zeno_pelgrims_retroreflector_shader_final_01

     

    zeno_pelgrims_shadersxyz_retroreflector_shader_final_02

     

    zeno_pelgrims_shadersxyz_retroreflector_final_03

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