# A Rail Profile Measurement Method Based on Polarization Fusion Imaging

## TL;DR

A new method using polarization imaging improves rail profile measurement accuracy by reducing errors caused by exposure issues.

## Contribution

A novel polarization fusion imaging technique with a Segmented RANSAC algorithm is introduced for accurate rail profile measurement.

## Key findings

- The proposed method reduces rail profile measurement error from 0.137 mm to 0.081 mm.
- It achieves 40.9% improvement in measurement accuracy compared to traditional methods.
- The method avoids data loss in underexposed regions of the rail surface.

## Abstract

The smooth area on the rail surface causes abnormal exposure in the laser section image, resulting in measurement errors of the rail profile. To address this issue, a novel rail profile measurement technique based on polarization fusion imaging is proposed. A polarized camera is utilized to acquire the four-directional polarization component images, Stokes parameter images, linear polarization angle images, and linear polarization degree images of the rail laser section. A polarization image data fusion algorithm based on Segmented Random Sample Consensus (S-RANSAC) is designed using these images as data sources, and the optimal rail profile fitting curve is obtained. Experimental results demonstrate that the proposed method can still obtain accurate and effective rail profile data in regions where traditional methods fail to capture profile data. Compared with the traditional method, the measurement error of the rail profile is reduced from 0.137 mm to 0.081 mm, and the measurement accuracy is improved by 40.9%. Evidently, this method avoids data loss in key areas of the rail profile caused by local underexposure, thus significantly enhancing the measurement accuracy. This method can provide a valuable reference for high-precision measurement of the rail profile under complex working conditions.