Bugfix: Control Point Triangulation

[nushakrishnan]

This PR introduces a fix to the control point triangulation and evaluation pipeline. We thank Roham (@rzninvo) and Mahbod (@Ace3Z) for their microSLAM submission and for bringing this issue to our attention, which allowed us to identify and address the problem. We also apologize for the confusion this issue has caused regarding the recently reported microSLAM results.

The issue originated from an overlooked behavioral change introduced during a refactor in early October 2025 and affects all submissions evaluated after that change. The results reported in the paper and on the initial leaderboard are unaffected and remain correct. We have re-evaluated the affected submissions using the fix introduced in this PR and updated their corresponding leaderboard entries accordingly.

Specifically, during Sim(3) refinement, the triangulated control points were passed to Ceres as free parameter blocks. After optimization, those same point arrays were then used for scoring. As a result, the triangulated points themselves could be modified during the robust alignment phase, rather than remaining fixed.

This behavior becomes particularly problematic when the poses surrounding the control points are not geometrically consistent. In such cases, the triangulation has high uncertainty, allowing the control points to be pulled toward their target locations during alignment and thereby producing an overly favorable evaluation. As shown below, this issue has no measurable effect on highly robust systems such as Aria SLAM and only a marginal effect on the off-the-shelf systems we evaluated.

Method	Code	On leaderboard (as of Sept 13 2026)	Short	Medium	Long	Low light	Moving platform
Aria SLAM	With issue		90.7	78.5	70.9	84.2	55.0
Aria SLAM	Correct	✅	90.7	78.5	70.9	84.2	55.0
microSLAM	With issue	✅	64.5	74.5	82.3	78.3	85.6
microSLAM	Correct		23.9	15.5	7.1	14.6	3.7
DPVO	With issue		21.1	25.2	30.0	29.7	20.3
DPVO	Correct	✅	7.6	7.5	1.7	2.6	2.3
OpenVINS (bino, imu)	With issue		22.1	19.0	13.3	15.2	12.1
OpenVINS (bino, imu)	Correct	✅	18.9	15.9	12.5	13.9	10.4

Scores per challenge with the old and fixed evaluation code. Recall is unaffected. Submissions were affected since October 5 2025.