QEF Explainer
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A detailed technical explainer on Quadratic Error Functions (QEF) used in Dual Contouring and related isosurface extraction algorithms. Covers building A and B matrices, solving the QEF via SVD pseudo-inverse with rank-deficiency handling, compact matrix representation for memory efficiency, zero-allocation construction, constrained solving strategies (including a novel alternate approach), and advanced topics like merging subspace QEFs and semi-compact representations for dimension reduction. Grounded in the author's implementation work on libfive and the IOSPMR algorithm.
Table of contents
Author's noteThe basicsBuilding the A and B matricesSolving the QEFCompact representationFinding the error valueZero-allocation constructionWhither to place points?Sharp features on the distance field itselfSolving with constraintsAn alternate strategy for constrained solvingSaving and merging subspace QEFsSemi-compact representation for dropping dimensionsFinChangelogSort: