#1038 Rail Extraction Using Template Tools

Technote

Background

Extracting the rail lines is easy and efficient using TopoDOT's template tools (only available on MicroStation CONNECT). Following are a few methods on how to best create rail templates from lidar data based on their characteristics.

The most important characteristic is the relative density between the left and right sides of a rail. Usually, one side is consistently denser than another when rail is scanned with mobile data. This requires only one side of the rail to be modeled.

However, when scanned with static systems, the density may switch between sides as they near scan positions. This requires modeling on both sides of the rail. See Fig.1-2

Fig 1. The point density is thicker on the left side of the rail.
Fig 2. 12 meters down the same rail, the point cloud density is now thicker on the right side.
Note: This is due to this section of rail nearing a scan position.

For your convenience, a premade list of rail cells can be found under "C:\TopoDOT\Cells".

***These cells are NOT templates ready to be used. They are only for reference, and can be edited to fit and create a template specific to the rails in your project.

Static

A characteristic of static scans on rail data is that the point density and coverage is inconsistent. More importantly, the relative density between the left and right sides of a rail changes as they near scan positions. See Fig.1-2

In order to accommodate for these inconsistencies, it is important to create a template modeling both sides of the rail. See Fig. 3

Fig 3. Double sided rail template.

The process of generating and creating this template is detailed in the video below.

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