View Full Version : unic plastic shader - hard to creat
11-02-2005, 09:13 PM
hello all lightwave users
how are you
I was working on a plastic metirial - "volume" wheel of a guitar
I want to creat a plastic like in this pic (marked in red)
The render is one area light + backdrop GI[monte carlo] (the pics I used was probe rnl.hdr for the backdrop and some of them ware kitchen.hdr)
the area is 27 intensty and the GL intensity set for 75% (using Fprime)
some of the renders i used G2, i play with the color high lights, diffuse, reflaction and reflaction bluring.. no matter what i did ... i just can't get same result
I was thinking if the problem is with the lighting.. maybe i should have used backdrop GI with white color and soft liner lights?
the last one keep rendering at this time
Thanks for reading and sorry for bad english
11-02-2005, 10:53 PM
Do you have a gradient on the reflection to simulate fresnel effect? If you want highlights to be in specific places, add a poly to the scene with 100% luminosity, unseen by camera and radiosity, and move it around until you get them right. Your knob looks segmented in some pics, so try using subpatches or raise the number of sides on your disk (it might be the environment reflection thats making it look segmented)...And round off the top more to catch the light. Use a little bit of blurred reflection, 25% or so, also the plastic in the pic is a different color than yours.
11-03-2005, 01:23 AM
I like more your last tests. I guess your aren't getting the same results, mainly because your HDRI. If I'm not wrong, Philip Mayer should have used building_probe for that image; that lightprobe has the particularity that provide a strong lighting from only one side: up, the rest has very low lighting range.
There are several ways to get a plastic look (hehe, it's funny because some years ago we wanted to stay away from this), a way is to avoid reflections in that surface; use specular only (or very low values in reflection and an incidence_angle gradient for fresnel effect as Otacon has suggested), but use mainly specular (you may want to play with BRDF shader too). Due to your lighting setup, other way might be to use a spherical reflection map just for this surface, make a copy of your HDR and blur the image (you may want to use HDRExposure here or replace the HDRI for a LDR version)
Btw, you don't need an expensive lighting setup (MonteCarlo, etc), Philip Mayer used Overcaster (spinning lights) to get that nice image :)
11-03-2005, 03:44 AM
you may want to add a subtle bump map to the notches in the knobs to make them look slightly "stamped" into the plastic. If you do it right, you'll get s subtle distortion in the highlights that will sell the knobs more as real physical objects. hope that makes sense.
as far as the general plastic look, the other guys had good advice.
the reflections of the knobs in the guitar are overbright, though. It might be good to set the guitar wood reflection options to "Ray Tracing and Spherical Map" so that the reflections don't reflect your backdrop color, and aren't so bright. Alternately, you can use G2 to tone down the brightness of the reflections, and I'd add 5-10% reflection blurring to the wood so that the reflections of the knobs in the wood aren't razor sharp. It just doesn't seem quite realistic.
hope that advice isn't too nosey.
11-03-2005, 02:17 PM
I jus now got back from school and I can go on with the thing (finally ..)
monovich - "you may want to add a subtle bump" you mean that I use bump map to brake the reflection ?
gerandr, what is "spinning lights" you mention ?]
edit - I was searching for the HDR map name building on the light probe gallery but i have not fined it
Where can I find this map ?
11-03-2005, 05:16 PM
I meant that where you have black notches on the knobs, use a bump map to make the black notches recessed just a tiny bit. It's hard to explain, but look at a real guitar knob and you will see what I mean.
11-05-2005, 10:37 AM
I try the plastic and a new Metalic Surface
11-05-2005, 11:09 AM
I think you are getting it.
About spinning lights you may want to learn from the LW genius "he who has" shared the technique in this ancient tutorial (http://www.mohhs.com/lw/pdf/SpinningLight.pdf)
Overcaster (http://www.kolumbus.fi/erkki.halkka/plugpak/Overcaster_frame.html) is a group of tools created by the brilliant Ekki Halkka that automates the trick for lighting purposes (check all his plugins, has very interesting and useful tools)
building_probe comes in your LW Content; but I'd recommend you not use it, because you should be able to get a plastic surface with any environment, as you are doing it now :)
11-05-2005, 11:09 AM
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