Esri Grid
A raster GIS file format developed by Esri, which has a binary and an ASCII format.
Esri Grid is a commonly utilized spatial data format in GIS (Geographic Information System). Developed by Esri (Environmental Systems Research Institute), it represents geographic data in the raster form. This data format is distinct because of its cell-based approach, where each cell has a value representing the feature attribute. Applications of Esri Grid are seen predominantly in topographic modeling, landscape ecology, and spatial analysis.
Esri Grid comes in two formats: binary and ASCII. The binary format is more compact and allows for more efficient processing and storage. It offers the advantage of storing both integer and floating-point raster data type. Therefore, it's appropriate for storing continuous data, such as elevation, slope, or temperature, and categorical data, for instance, land cover types.
On the other hand, the ASCII format, known as ASCII grid, is a less compact variation that represents data as plain text numbers, facilitating the reading and editing of files by users. However, ASCII format only supports integer data type, limiting its use to storing only categorical data types like land use and land cover types.
In the binary format, the data is stored in cells with a header containing the critical metadata, including the number of columns and rows, cell size, and coordinates of the lower left corner of the grid. Simplistically put, in Esri Grid, both the attribute data and the geographic data are stored in a cell-based manner.
For ASCII Grid, the data comes with a simple header defining the grid structure, including the number of rows and columns, and cell size. After the header, the cell values are listed in row order from top to bottom. The cell values are separated by space and each row ends with a carriage return.
Esri Grid has unique characteristics that set it apart from other raster formats. The value of each cell is determined by the majority of occurrences of the value within the cell. It can handle raster datasets with an attribute table and supports the seamless mosaicking of multiple grids. Its multi-band capabilities mean that the cell values in the grid can be constituted by more than one band of information, extending its use to more complex, layered applications in imagery and remote sensing.
However, there are notable limitations to Esri Grid data format. It has a filename restriction where the file name must be no more than 13 characters but can contain letters, numbers, and underscores. Besides, the file needs to be stored directly in the workspace folder, not in any subfolders.
Despite these restrictions, the Esri Grid format remains a powerful tool in GIS for its versatile range of applications and the capacity to store continuous and categorical data. Its robust methodology of integrating geographic information using a cell-based approach supports intricate geographical analysis and topographic modeling.
