Raster Data

Definition

Raster data, in the field of Geographic Information Systems (GIS), is a type of geospatial data that is represented in a grid or a matrix format. It comprises pixels or cells, with each pixel having specific geographic coordinates and a value that represents a particular characteristic or attribute.

Raster data is majorly used to represent continuous, normally varying features, such as elevation, temperature, or soil pH. Each cell within a raster contains a single value and when visually represented, these values provide a comprehensive view of the geographical area concerned.

The raster data model is a central component of digital image processing and plays an important role in remote sensing applications.

What is Raster Data?

Raster data, sometimes referred to as grid data, is a digital data structure used to capture, represent, and store spatial data that vary on a continuous scale. Unlike vector data, which represents specific attributes and coordinates as distinct objects (such as points, lines, and polygons), raster data divides the attribute's spatial domain into a regular grid of cells.

The raster data model can portray a variety of information. For example, satellite or aerial images use the raster data model to display the Earth's terrain or landscape. Each pixel in these images represents a specific area on the Earth's surface. The pixel's value indicates particular information such as reflected light or temperature measurements.

This data model is also highly effective when processing complex mathematical, statistical, and spatial operations because raster operations can be easily performed one pixel at a time.

FAQs

What are the advantages of raster data?

Raster data offers several advantages. Here are a few:

1. It is perfect for mapping continuous data such as elevation, temperature, etc.
2. It allows for the manipulation and analysis of map data based on the mathematical capabilities of computers.
3. High spatial resolution can be achieved, given the regular grid structure.

What are the limitations of raster data?

There are several limitations to raster data:

1. It can be memory intensive due to the size of the data especially for high resolution images.
2. It may not accurately represent complex linear features, particularly at smaller scales.
3. There might be issues with resolution: a cell of raster data can contain only one attribute value, which can result in information loss.

Is satellite imagery a type of raster data?

Yes, satellite imagery is a type of raster data. It consists of a matrix of cells (or pixels) organized into a grid. Each pixel contains a value that represents information, such as temperature or reflected light.

How does raster data differ from vector data?

Unlike raster data, vector data represents geographical features in point, line, or polygon form. These features are based on vertices and paths instead of grid cells. Vector data is particularly optimal for representing boundaries, roads, and other discrete features. It offers the advantage of smaller file sizes and clearer definition of features, unlike raster data.