arXiv Computer Vision

Hold-Out Self-Validation Cannot Certify Photogrammetric Accuracy: Saturation and Blindness to Coherent Distortion

The paper argues that internal self-consistency checks cannot guarantee the accuracy of photogrammetric reconstructions, a limitation that is structural rather than a tuning issue. It introduces a track‑leakage‑free hold‑out protocol that withholds a deterministic subset of images and tests each against only 3D points supported by at least two retained images, ensuring no view is evaluated against the structure it helped create. Experiments on diverse datasets show that while the protocol is well‑posed, it saturates at a confidence score of 1.00 and fails to detect coherent distortion, missing large errors that can reach over 100 m. whyItMatters":"The study highlights that hold‑out self‑validation scores, increasingly used as quality evidence for metric deliverables, may be misleading and cannot replace external survey validation."

arXiv Computer Vision
Sep 11

A Calibration Audit of Confidence in Feed-Forward 3D Reconstruction Models

The paper audits the confidence outputs of seven feed‑forward 3D reconstruction backbones across 13 datasets, evaluating four properties: error ranking, average error‑to‑uncertainty ratio, slope of this ratio, and coverage of the implied error distribution. While confidence ranks errors well, the decoded uncertainty is consistently too small—off by at least 2.4× on median cases—and worsens with higher confidence. A post‑hoc power‑law fit per backbone‑dataset pair improves all four metrics at the dataset level, reducing the median error by 1.35×, but fails to correct coverage for many held‑out scenes, indicating the models lack the correct error scale and distribution shape.

By Nanxing Nick Deng, Qing Cheng, Niclas Zeller, Daniel Cremers
arXiv Computer Vision
Oct 8

Do Vision Models Learn Physical Constraints or Rendering Shortcuts? A Counterfactual Benchmark for Grounded Physical Consistency

The paper introduces a counterfactual benchmark to evaluate whether vision models understand physical constraints or merely learn rendering shortcuts. Using Mitsuba 3, it generates 5,500 synthetic images across 500 scene families, each with a clean image and ten violations (shadows, reflections, support, surface response, occlusion). Diagnostic baselines (LLaVA‑1.5‑7B, Qwen2.5‑VL‑7B, InternVL3.5‑8B) achieve 64.0–67.8 % macro‑F1 on a held‑out synthetic test set, but performance drops to 40.8 % for LLaVA‑1.5‑7B under an intervention shift, indicating reliance on rendering cues rather than true physical reasoning.

By M. Moein Esfahani, Sepehr Salem, Mohammed Alser, Vince Calhoun
arXiv Computer Vision
6d ago

Does VGGT Know What It Does Not Know?

arXiv:2610.35806v1 Announce Type: new Abstract: Feed-forward 3D reconstruction models such as VGGT regress cameras and geometry in a single forward pass, but they report no uncertainty for the camera...

By Adityan Thirumani Srinivasan, David Nordstr\"om
arXiv Computer Vision
5d ago

ObjectTwin: Measuring the Asset Correspondence Gap for Capture-Anchored Digital Twins

ObjectTwin introduces a scan‑grounded protocol for measuring how well generated 3D assets match captured scenes. By fixing the scene, cameras, and depth data and only swapping the object representation, the method quantifies the asset correspondence gap—how much observation agreement is lost compared to the scan‑derived geometry. Experiments on two indoor RGB‑D datasets and two generation backends show that anchored generated assets lose 0.302–0.497 MaskIoU, with scene‑level estimates consistently positive but generator preferences varying across domains.

By Zhenghe Guo
arXiv Computer Vision
Oct 12

Complexity-Calibrated Reconstruction Discrepancy for No-Reference Point Cloud Quality Assessment

The paper introduces a no-reference point cloud quality assessment method that leverages a complexity‑calibrated reconstruction discrepancy. By reconstructing a distorted point cloud and comparing successive reconstructions with varying smoothing, the approach isolates a proxy for structural complexity, which is then used to calibrate the initial reconstruction error. The calibrated geometric and projected‑view discrepancies, measured with frozen pretrained perceptual representations, are fused into a final degradation score without requiring any PCQA‑specific training.

By Haocheng Wu, Xiangjie Sui, Xin Sun