It's useful to calculate sphere projection in clip space. One usage is to determine LOD of a model. As you might have known, sphere projection results in ellipse instead of sphere. In this post, a way to approximate radius of projected sphere is given.

Assume the sphere is in the center of the screen and we know the \(FOV\) of the camera, sphere radius \(r\) and distance from camera \(z\). Looking at the diagram below:


The approximate projection of sphere radius in clip space is given by:

$$ approx\_projected\_radius = \frac{y}{y_{max}} = \frac{r}{z \times \tan (\frac{FOV}{2})} $$


Here are my growing links to GDC 2016 slides/presentations:

Programming

Advanced VR Rendering Performance - Alex Vlachos
An Excursion in Temporal Supersampling - Marco Salvi
An Introduction to SPIR-V - Neil Henning
Building a Better Jump - J. Kyle Pittman
Developing the Northlight Engine: Lessons Learned - Ville Timonen
Enlighten feature sets for large world games - Geomerics
Fast, Flexible, Physically-Based Volumetric Light Scattering – Nathan Hoobler
Fixed Point Iteration - Huw Bowles
The runtime asset format forGL-based applications - Patrick Cozzi, Tony Parisi
Improving Geometry Culling for ‘Deus Ex: Mankind Divided – Nicolas Trudel
More Explosions, More Chaos, and Definitely More Blowing Stuff Up: Optimizations and New DirectX Features in Just Cause 3 - Antoine Cohade & Emil Persson
Object Space Lighting - Dan Baker
Real-Time BC6H Compression on GPU - Krzysztof Narkowicz
Stable Specular Hightlights – Anton S. Kaplanyan
Taming the Jaguar - Andreas Fredriksson
TLDR Statistics for Game Devs - Elan Ruskin

Attendees Coverage

DirectX 12 Advancements - Max McMullen
Motion Matching and The Road to Next-Gen Animation – Simon Clavet

Production

40 VR/AR Predictions - Jesse Schell
Great Management of Technical Leads - Mike Acton

Video Links

Epic Games
Khronos Session
Microsoft
Unity
Marmoset Toolbag | GDC 2016 Showcase - Marmoset Co
Seastack Bay - Geomerics
PowerVR at GDC 2016: Vulkan and OpenGL ES ray tracing - Imagination Technologies
CryEngine GDC 2016 Announcement - Crytek
GDC 2016 Allegorithmic Substance Showreel - Allegorithmic

Other Links

GDC 2016 Presentations - Krzysztof Narkowicz