POV-Ray : Newsgroups : povray.advanced-users : Apparent circular pattern of scratches : Re: Apparent circular pattern of scratches Server Time
25 Feb 2024 01:16:07 EST (-0500)
  Re: Apparent circular pattern of scratches  
From: Thomas de Groot
Date: 23 Jan 2019 02:32:26
Message: <5c48188a$1@news.povray.org>
On 23-1-2019 1:46, Bald Eagle wrote:
> I'm sure everyone has seen this at some point:
> 
> When you look at a light source's reflection on a smooth piece of glass or metal
> or plastic, the scratches all tend to appear as a series of arcs and lines
> roughly in a circular pattern centered around the "hotspot".
> 
> I was wondering if anyone has ever attempted to replicate this effect, and
> perhaps has an optical explanation for why the scratches appear in a circular
> pattern.
> 
> 
>
https://st.depositphotos.com/1032492/3139/i/950/depositphotos_31397463-stock-photo-texture-of-scratched-metal-surface.j
> pg

This one gets 404.

> 
> https://thumbs.dreamstime.com/thumblarge_2060/20605588.jpg
> 
> http://cpi.studiod.com/getty/caf73bdee00eeaa57d5e24c213f6b09c.jpg
> 
>
http://www.performancemotorcare.com/blog/wp-content/uploads/2011/06/How_to_avoid_swirl_marks.jpg
> 
> https://www.wavesdetailpro.com.au/wp-content/uploads/2017/08/poi-1.jpg
> 
> ..... you get the idea.
> 
> 

Let me try an explanation: assuming that all scratches are randomly 
orientated, only those parallel(?) to the light source get reflected 
maximally, all others are dimmer or - when perpendicular to the light 
source - do not reflect at all.

-- 
Thomas


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