631 research outputs found
Exact Ground States of Large Two-Dimensional Planar Ising Spin Glasses
Studying spin-glass physics through analyzing their ground-state properties
has a long history. Although there exist polynomial-time algorithms for the
two-dimensional planar case, where the problem of finding ground states is
transformed to a minimum-weight perfect matching problem, the reachable system
sizes have been limited both by the needed CPU time and by memory requirements.
In this work, we present an algorithm for the calculation of exact ground
states for two-dimensional Ising spin glasses with free boundary conditions in
at least one direction. The algorithmic foundations of the method date back to
the work of Kasteleyn from the 1960s for computing the complete partition
function of the Ising model. Using Kasteleyn cities, we calculate exact ground
states for huge two-dimensional planar Ising spin-glass lattices (up to
3000x3000 spins) within reasonable time. According to our knowledge, these are
the largest sizes currently available. Kasteleyn cities were recently also used
by Thomas and Middleton in the context of extended ground states on the torus.
Moreover, they show that the method can also be used for computing ground
states of planar graphs. Furthermore, we point out that the correctness of
heuristically computed ground states can easily be verified. Finally, we
evaluate the solution quality of heuristic variants of the Bieche et al.
approach.Comment: 11 pages, 5 figures; shortened introduction, extended results; to
appear in Physical Review E 7
Connecting the Dots: Floorplan Reconstruction Using Two-Level Queries
We address 2D floorplan reconstruction from 3D scans. Existing approaches
typically employ heuristically designed multi-stage pipelines. Instead, we
formulate floorplan reconstruction as a single-stage structured prediction
task: find a variable-size set of polygons, which in turn are variable-length
sequences of ordered vertices. To solve it we develop a novel Transformer
architecture that generates polygons of multiple rooms in parallel, in a
holistic manner without hand-crafted intermediate stages. The model features
two-level queries for polygons and corners, and includes polygon matching to
make the network end-to-end trainable. Our method achieves a new
state-of-the-art for two challenging datasets, Structured3D and SceneCAD, along
with significantly faster inference than previous methods. Moreover, it can
readily be extended to predict additional information, i.e., semantic room
types and architectural elements like doors and windows. Our code and models
are available at: https://github.com/ywyue/RoomFormer.Comment: CVPR 2023 camera-ready. Project page:
https://ywyue.github.io/RoomForme
Improving instrument detection for a robotic scrub nurse using multi-view voting
Purpose: A basic task of a robotic scrub nurse is surgical instrument detection. Deep learning techniques could potentially address this task; nevertheless, their performance is subject to some degree of error, which could render them unsuitable for real-world applications. In this work, we aim to demonstrate how the combination of a trained instrument detector with an instance-based voting scheme that considers several frames and viewpoints is enough to guarantee a strong improvement in the instrument detection task. Methods: We exploit the typical setup of a robotic scrub nurse to collect RGB data and point clouds from different viewpoints. Using trained Mask R-CNN models, we obtain predictions from each view. We propose a multi-view voting scheme based on predicted instances that combines the gathered data and predictions to produce a reliable map of the location of the instruments in the scene. Results: Our approach reduces the number of errors by more than 82% compared with the single-view case. On average, the data from five viewpoints are sufficient to infer the correct instrument arrangement with our best model. Conclusion: Our approach can drastically improve an instrument detector’s performance. Our method is practical and can be applied during an actual medical procedure without negatively affecting the surgical workflow. Our implementation and data are made available for the scientific community (https://github.com/Jorebs/Multi-view-Voting-Scheme)
- …