Fresnel Reflection Falloff

During last week’s ‘educational’ trip myself and two colleagues took a group of learners to visit Peppa Pig World in Paulton’s Park. Whilst the group were more interested in the rides than they were in Peppa or George, my imagination was captivated by a floating globe at the park’s entrance.

Before starting this project I believed that reflections were always brightest at the edges of any given object. Whilst a sphere has no tangible edge, to the viewer there is a perceived edge, my belief was that this outside edge is always more reflective than the centre. In 3D, this is achieved by using what is called a Fresnel gradient in the material’s reflection channel. These Chrome Effect Smileys are a good example of this.

Fresnel Reflection in 3D and CGI

Chrome Effect Smileys

As I wandered around this floating globe I was pleased to see that this theory proved to true (note in the second image how the colour of the red roof tiles changes), however, the transition from bright to dark reflection happened far quicker than I expected. My guess is that this is because, from the viewer’s perspective, the angle at which the light is bouncing must change quickly as the angle of the sphere’s surface changes. This is something that will need further research but as I’ve already said that I’d make a post about how the HDRI Panorama was used as a source of light, this research will have to come later.

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3 thoughts on “Fresnel Reflection Falloff

  1. Pingback: Using an equirectangular HDRI panorama to light a 3D scene | Photorealism in 3D CGI Imagery

  2. Pingback: Render Comparisons | Photorealism in 3D CGI Imagery

  3. Everything is very open with a precise clarification of the issues.
    It was really informative. Your website is extremely
    helpful. Many thanks for sharing!

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