Author name cluster

Zhikai Li

Possible papers associated with this exact author name in Arrow. This page groups case-insensitive exact name matches and is not a full identity disambiguation profile.

3 papers

2 author rows

AAAI Conference 2026 Conference Paper

SAQ-SAM: Semantically-Aligned Quantization for Segment Anything Model

Jing Zhang
Zhikai Li
Chengzhi Hu
Xuewen Liu
Qingyi Gu

Segment Anything Model (SAM) exhibits remarkable zero-shot segmentation capability; however, its prohibitive computational costs make edge deployment challenging. Although post-training quantization (PTQ) offers a promising compression solution, existing methods yield unsatisfactory results when applied to SAM, owing to its specialized model components and promptable workflow: (i) The mask decoder's attention exhibits extreme activation outliers, and we find that aggressive clipping (even 100x), without smoothing or isolation, is effective in suppressing outliers while maintaining performance. Unfortunately, traditional distribution-based metrics (e.g., MSE) fail to provide such large-scale clipping. (ii) Existing quantization reconstruction methods neglect semantic interactivity of SAM, leading to misalignment between image feature and prompt intention. To address the above issues, we propose SAQ-SAM in this paper, which boosts PTQ for SAM from the perspective of semantic alignment. Specifically, we propose Perceptual-Consistency Clipping, which exploits attention focus overlap to promote aggressive clipping while preserving semantic capabilities. Furthermore, we propose Prompt-Aware Reconstruction, which incorporates image-prompt interactions by leveraging cross-attention in mask decoder, thus facilitating alignment in both distribution and semantic. Moreover, to ensure the interaction efficiency, we design a layer-skipping strategy for image tokens in encoder. Extensive experiments are conducted on various SAM sizes and tasks, including instance segmentation, oriented object detection, and semantic segmentation, and the results show that our method consistently exhibits advantages. For example, when quantizing SAM-B to 4-bit, SAQ-SAM achieves 11.7% higher mAP than the baseline in instance segmentation task.

PDF Details DOI

ICML Conference 2025 Conference Paper

Unsupervised Learning for Class Distribution Mismatch

Pan Du 0002
Wangbo Zhao
Xinai Lu
Nian Liu
Zhikai Li
Chaoyu Gong
Suyun Zhao
Hong Chen 0001

Class distribution mismatch (CDM) refers to the discrepancy between class distributions in training data and target tasks. Previous methods address this by designing classifiers to categorize classes known during training, while grouping unknown or new classes into an "other" category. However, they focus on semi-supervised scenarios and heavily rely on labeled data, limiting their applicability and performance. To address this, we propose Unsupervised Learning for Class Distribution Mismatch (UCDM), which constructs positive-negative pairs from unlabeled data for classifier training. Our approach randomly samples images and uses a diffusion model to add or erase semantic classes, synthesizing diverse training pairs. Additionally, we introduce a confidence-based labeling mechanism that iteratively assigns pseudo-labels to valuable real-world data and incorporates them into the training process. Extensive experiments on three datasets demonstrate UCDM’s superiority over previous semi-supervised methods. Specifically, with a 60% mismatch proportion on Tiny-ImageNet dataset, our approach, without relying on labeled data, surpasses OpenMatch (with 40 labels per class) by 35. 1%, 63. 7%, and 72. 5% in classifying known, unknown, and new classes.

Details

IROS Conference 2020 Conference Paper

Online Localization with Imprecise Floor Space Maps using Stochastic Gradient Descent

Zhikai Li
Marcelo H. Ang
Daniela Rus

Many indoor spaces have constantly changing layouts and may not be mapped by an autonomous vehicle, yet maps such as floor plans or evacuation maps of these places are common. We propose a method for an autonomous robot to localize itself on such maps with inconsistent scale using Stochastic Gradient Descent (SGD) with scan matching using a 2D LiDAR. We also introduce a new scale state in 2D localization to manage the possible inconsistent scale of the input map. Experiments are conducted in an indoor corridor using three different input maps - a point cloud, a floor plan, and a hand-drawn map. The SGD localization algorithm is bench-marked to Adaptive Monte Carlo Localization (AMCL). In a point cloud mapped environment, our algorithm achieves 0. 264m and 5. 26° average position and heading error respectively. On the hand-drawn map, our SGD localization algorithm remains robust while AMCL fails. The role of the scale state in our SGD localization algorithm is demonstrated in poorly scaled maps.

Details