A grid is an overlay layer that shows a continuous gradation of color to represent interpolated values from the underlying data. User-controlled properties of a grid include brightness, contrast, opacity, grayscale, transparency, and an inflection collection (how the colors are defined and spread).
A grid is a raster that is generated from a sparse set of points and their values. A raster is made up of pixels, each with a value. Grids are created on the fly as part of a mapping service request. They are not stored in the repository as a named layer.
During the interpolation process, every pixel value is assigned an estimated value influenced by the known data values, interpolator weighting algorithm and aggregation method. Once the grid is created, the known and interpolated values are grouped into inflections (bins) and assigned colors. When the grid is displayed, the colors are spread evenly to reflect the gradation of values. Inflections can be pre-calculated and sent via a GridStyle that takes an InflectionList or can be calculated at run-time.
Previously created grids from grid creation tools can be displayed as the results of a service request.
Spectrum™ Technology Platform supports the IDW interpolator (inverse distance weighting) which is suitable for most grid applications, including sparse data sets.
For more information on the schema elements for grids, see GridLayer Elements