Visual Effects Summit: Lessons in Lens Flares

Summary

In this detailed presentation, Anno, a real-time VFX artist, explores the art and techniques of creating lens flares in visual effects. Over his 20-year career as a photographer, filmmaker, and animator, Anno discusses the behaviors and characteristics of lens flares, emphasizing the differences between spherical and anamorphic lenses. He covers key flare elements such as ghosts, glare, halos, and chromatic aberration, while demonstrating his process for designing custom lens flares using After Effects. This talk provides both artistic insights and practical tips for VFX artists interested in enhancing their flare creation skills.

Takeaways

• 😀 Lens flares are a crucial visual element in real-time VFX, influenced by the interaction of light and camera lenses.
• 😀 There are two main types of lenses: spherical and anamorphic, each producing distinct flare behaviors.
• 😀 Spherical lenses create radial rays and circular or polygonal bokeh, with flare elements corresponding to the number of aperture blades.
• 😀 Anamorphic lenses produce horizontal streaks, vertical oval-shaped bokeh, and have more asymmetrical flare patterns compared to spherical lenses.
• 😀 Light source angle and focal length influence the visibility and behavior of lens flare elements, with glancing angles producing subtle effects and direct angles creating stronger flares.
• 😀 Ghosts in lens flares are bokeh-like elements that rotate around the light source, often appearing as inverted copies of it.
• 😀 Flare elements such as glare, ghosts, halos, and chromatic aberration can change their shape, intensity, and color depending on lens type, focal length, and other factors.
• 😀 The depth of field, or focus distance, directly impacts flare elements, causing them to become softer or sharper based on whether the light source is in focus.
• 😀 Chromatic aberration leads to color fringing around flare elements, especially at the edges of the image, influencing the overall appearance of lens flares.
• 😀 In game engine flare creation, understanding the screen space position of the light source is key to driving the behavior of flare elements, like scale, opacity, and position.

Q & A

What is the primary focus of the talk regarding lens flares?

The talk focuses on the key behaviors of different lens flares and how to create your own, rather than providing a technical walkthrough on how to implement them in specific game engines.

What are the two major types of lenses discussed, and how do they differ in terms of flare behavior?

The two major types of lenses discussed are spherical and anamorphic lenses. Spherical lenses produce radial rays and circular or polygonal bokeh, whereas anamorphic lenses create horizontal streaks and vertically stretched bokeh, contributing to a more cinematic look.

How do aperture blades affect lens flare behavior?

Aperture blades control the size of the aperture, and the number of aperture blades typically correlates with the number of radial rays or polygonal shapes in lens flares, influencing the flare's appearance.

What is the impact of chromatic aberration on lens flares?

Chromatic aberration, or color fringing, occurs when a lens fails to converge all colors to the same point, often causing color fringing around flare elements like ghosts and halos, particularly near the edges of the image.

What is the difference in flare behavior when using wide-angle versus telephoto lenses?

Wide-angle lenses tend to produce many smaller ghosts and flare elements, while telephoto lenses typically generate fewer but larger ghosts and flare elements, due to differences in focal length and perspective.

How does the interaction between light and the camera lens affect flare creation?

The interaction between light and the lens elements—such as reflections and refractions—greatly influences the shapes, colors, and behaviors of lens flares. Understanding this journey of light is crucial in creating realistic and compelling flares.

What is the significance of the aspect ratio in lens flare creation, especially for anamorphic lenses?

Anamorphic lenses produce a 2.39:1 aspect ratio, which is then de-squeezed to 21:9 for a cinematic look. Understanding this unique aspect ratio is essential when working with anamorphic flares, as it influences the visual outcome.

What are 'ghosts' in the context of lens flares, and how do they behave?

Ghosts are bokeh-like elements that rotate around the center of the screen, often appearing as copies or inverted copies of the light source. They can behave erratically, with their shape and color shifting as the light source is occluded.

What role do 'lens dirt' and reflections play in creating lens flares?

Lens dirt, similar to dirt on a car windshield, can create soft out-of-focus bokeh shapes when illuminated. Additionally, reflections from the lens elements can combine with the dirt, resulting in unique and often unpredictable flare elements.

What is the importance of understanding screen space position and light source distance when creating a lens flare in a game engine?

Knowing the screen space position of the light source and its distance from the center of the screen is crucial in driving the behaviors of flare elements, such as their movement and opacity, ensuring that the flare matches the visual context of the scene.