Explain the difference between Raster and Vector charts.
Raster and vector charts are two types of electronic navigational charts (ENCs) that are commonly used by mariners for navigation purposes.
While both types of charts serve the same purpose of providing a visual representation of the sea area and its surroundings, they differ in terms of their characteristics, data handling, and application.
Raster charts are digital versions of paper charts, and they are essentially scanned images of the paper charts. They consist of pixels that represent the various features and characteristics of the sea area, such as landmasses, depth contours, navigation aids, and hazards. Raster charts are easy to use and are widely available, making them a popular choice for small vessels and recreational boaters. However, they have limited functionality and can only provide basic navigation information. Additionally, because they are essentially scanned images, they can become distorted and lose their accuracy if they are enlarged or zoomed in too much.
On the other hand, vector charts are made up of vector data, which is essentially a set of mathematical coordinates that define the location and characteristics of features on the chart. Vector charts are highly detailed and can display a vast array of information, including water depths, coastlines, buoys, lighthouses, and other navigational aids. They can also provide additional features, such as tide and current information, and can be updated easily to reflect changes to the sea area. Furthermore, because vector charts are made up of mathematical coordinates, they can be easily zoomed in or out without losing their accuracy or resolution.
One of the main differences between raster and vector charts is the way they handle data. Raster charts are essentially images, and as such, they are static and cannot be updated or edited easily. Vector charts, on the other hand, are dynamic and can be updated easily to reflect changes to the sea area. Additionally, vector charts can be customized to display only the information that is relevant to the user, while raster charts provide a fixed set of information that cannot be altered.
Another difference between the two types of charts is their application. Raster charts are typically used for simple navigation purposes and are popular among small vessels and recreational boaters. Vector charts, on the other hand, are more advanced and are often used by commercial vessels, such as cargo ships and tankers, that require highly accurate and detailed information to navigate safely. In addition, vector charts are often used in conjunction with electronic chart display and information systems (ECDIS), which provide advanced features such as route planning, real-time tracking, and collision avoidance.
In conclusion, while raster and vector charts both serve the same purpose of providing a visual representation of the sea area and its surroundings, they differ in their characteristics, data handling, and application. Raster charts are simple to use and widely available, while vector charts are highly detailed and can be updated easily to reflect changes to the sea area. Ultimately, the choice of which type of chart to use will depend on the user’s specific needs and requirements.