Release 4 was heavily optimized for difficult tasks like reconstructing motion capture data (e.g., facial expressions) even when filmed with complex anamorphic lenses. Essential Resources for Release 4

A step-by-step video for downloading, running, and fetching licenses for Release 4.

One of the headline features was the addition of more sophisticated point constraints, allowing for better handling of near/far-point constraints to prevent inverted point clouds.

While Release 4 is robust, newer versions offer critical modern features: 3DEqualizer4 [featurette] - Release 4: What's New

This version refined the calculation core, which uses unique techniques to automatically compute individual weighting curves for every point, effectively weeding out "outliers" (tracking errors) on the fly.