Op 21/12/2019 om 02:31 schreef AndreyG:
> I image wood textured surface covered with glass.
> Camera positioned perpendicular to imaged surface
> Illumination done using Parallel light source.
> Light falls perpendicular to imaged surface.
> When there is no glass camera shows image with uniformal brightness across the
> field – what I would expect.
> When image overlaid with glass camera depicts bright spot right in the centre of
> the image.
> As it is shown here:
> https://imgur.com/a/xzflV2T
> 
> What causes bright spot? Is it reflection of light source? But there is no
> source, all light rays a parallel and fall perpendicularly to the surface. What
> causes bright spot?
> 
> 

It is the reflection of the light source. In your case, I assume you have:

light_source {
   <0, 0, 0>
   color rgb YourColor
   translate YourLightPosition
   parallel
}

The term parallel does not mean that the light source becomes a wide, 
flat, surface. It remains a point light and is reflected as such. 
Parallel only means that the incident light rays on the surface from a 
very distant source are parallel, like for instance Sun light. See:

http://wiki.povray.org/content/Reference:Light_Source#Parallel_Lights

-- 
Thomas

Post a reply to this message