|
Curve extraction plays a pivotal role in various fields such as medical imaging, road mapping etc.,
involving the identification of curves from images. Our research focuses on Railway Engineering
Scale Plan (ESP) images, aiming to automatically categorise railway lines as tracks and points
within these images. Employing a curve extraction algorithm, we initiate the process by selecting
a single curve and tracing it throughout the image to capture all edges effectively. The algorithm
is designed to classify curves that intersect each other, disappear, and reappear, with the goal
of producing results that closely resembling human identification of railway lines. Railway lines
normally meet at points but crossing may also happen. Initially, identifying railway tracks as
curves or edges in images is achieved using computer vision techniques. Preprocessing techniques
like smoothing, edge detection, and thresholding enhance image features and reduce noise. Object
detection algorithms are then utilized to identify railway tracks within the pre-processed images.
Subsequently, the curve-tracing algorithm is applied to follow the paths of the identified railway
tracks throughout the image. This algorithm accounts for the curvature of the tracks and the
presence of other curves in the image. Once the curves have been identified, the curve-tracing
algorithm can be applied to follow their path throughout the image using Steger’s Curve tracing
algorithm. Unlike existing methods, we continue tracing the existing curve while handling intersecting curves as separate tracks, as railway lines intersection should be traced differently than
standard intersecting curves extraction. We also incorporate the concept of looking a distance
ahead, to continue tracing curves for disappearing and reappearing curves in images. Moreover,
railway lines have specific properties such as being long, smooth, and continuous with minimal
abrupt changes in direction. To address this, we have done a filtration based the characteristics
of the railway tracks. We developed a method for filtering curves based on the analysed railway
tracks and points properties, ensuring that only curves supporting railway characteristics are retained. While working with images of railway plan we may have very large image plans to work
with which usually have issues with memory storage and complex computations. We address this
by processing images tile by tile, effectively capturing small track details with minute features.
Additionally, we bridge gaps in rail lines by identifying similar characteristic curves in image and
joining them to form single tracks, which are then classified and labelled. Furthermore, we imple-
mented a piece-wise spline approximation of lines and points to obtain smoother curves. These
curves can be incorporated into Signal Interlocking Plans (SIP) automatically for signalling and
interlocking purposes, contributing to railway infrastructure management and automation
| |
|
Keywords:
Tracks, tracing, ESP, classification, filtration, intersecting curves,
bridging gaps, cubic spline, SIP
|