Anomalies by Synthesis: Anomaly Detection using Generative Diffusion Models for Off-Road Navigation

Fuente: arXiv
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Hauptverfasser: Ancha, Siddharth, Jiang, Sunshine, Manderson, Travis, Brandt, Laura, Du, Yilun, Osteen, Philip R., Roy, Nicholas
Format: Preprint
Veröffentlicht: 2025
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author Ancha, Siddharth
Jiang, Sunshine
Manderson, Travis
Brandt, Laura
Du, Yilun
Osteen, Philip R.
Roy, Nicholas
author_facet Ancha, Siddharth
Jiang, Sunshine
Manderson, Travis
Brandt, Laura
Du, Yilun
Osteen, Philip R.
Roy, Nicholas
contents In order to navigate safely and reliably in off-road and unstructured environments, robots must detect anomalies that are out-of-distribution (OOD) with respect to the training data. We present an analysis-by-synthesis approach for pixel-wise anomaly detection without making any assumptions about the nature of OOD data. Given an input image, we use a generative diffusion model to synthesize an edited image that removes anomalies while keeping the remaining image unchanged. Then, we formulate anomaly detection as analyzing which image segments were modified by the diffusion model. We propose a novel inference approach for guided diffusion by analyzing the ideal guidance gradient and deriving a principled approximation that bootstraps the diffusion model to predict guidance gradients. Our editing technique is purely test-time that can be integrated into existing workflows without the need for retraining or fine-tuning. Finally, we use a combination of vision-language foundation models to compare pixels in a learned feature space and detect semantically meaningful edits, enabling accurate anomaly detection for off-road navigation. Project website: https://siddancha.github.io/anomalies-by-diffusion-synthesis/
format Preprint
id arxiv_https___arxiv_org_abs_2505_22805
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Anomalies by Synthesis: Anomaly Detection using Generative Diffusion Models for Off-Road Navigation
Ancha, Siddharth
Jiang, Sunshine
Manderson, Travis
Brandt, Laura
Du, Yilun
Osteen, Philip R.
Roy, Nicholas
Robotics
Computer Vision and Pattern Recognition
Machine Learning
In order to navigate safely and reliably in off-road and unstructured environments, robots must detect anomalies that are out-of-distribution (OOD) with respect to the training data. We present an analysis-by-synthesis approach for pixel-wise anomaly detection without making any assumptions about the nature of OOD data. Given an input image, we use a generative diffusion model to synthesize an edited image that removes anomalies while keeping the remaining image unchanged. Then, we formulate anomaly detection as analyzing which image segments were modified by the diffusion model. We propose a novel inference approach for guided diffusion by analyzing the ideal guidance gradient and deriving a principled approximation that bootstraps the diffusion model to predict guidance gradients. Our editing technique is purely test-time that can be integrated into existing workflows without the need for retraining or fine-tuning. Finally, we use a combination of vision-language foundation models to compare pixels in a learned feature space and detect semantically meaningful edits, enabling accurate anomaly detection for off-road navigation. Project website: https://siddancha.github.io/anomalies-by-diffusion-synthesis/
title Anomalies by Synthesis: Anomaly Detection using Generative Diffusion Models for Off-Road Navigation
topic Robotics
Computer Vision and Pattern Recognition
Machine Learning
url https://arxiv.org/abs/2505.22805