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Understanding grid data

What is grid data?

While grid data can be visualised in a similar way to raster (image) data, they are in fact different kinds of data.

Grid data contain data values of cells in a regular grid. Grid data is essentially a range of values that are associated with specific coordinates. These values are then mapped onto a single colour band, to represent the variation across a particular extent.

For example, a bathymetry grid - that is, a grid representing the depth of an ocean floor - might have a value range of 1 - 5000 metres. Using a grayscale colour band, 1 would be represented in white, and 5000 in black. The grid would enable users to easily understand the relative depth of a particular body of water at a glance.

How do I know if I’m looking at grid data?

From the layer information page, the layer type is listed under Specifications. The data type will be listed as Grid (as opposed to Raster/Image for raster data sets) and will include a resolution value that describes the size of each cell.

How are grid data displayed on Koordinates?

Grid data are displayed on Koordinates as grayscale images. Because the range of values within the data could be any set of numbers, for display purposes the range is normalised to a grayscale gradient.

Users can query grid data by clicking the map, or by using our Query API. The spatial query will return the value associated with that particular point. Users may need to refer to supporting metadata to determine what this value refers to.

How is grid data handled in PDF?

We do not at present support the export of grid data to PDF. However, we do support the export of the representation of grid data previewed in your browser. Put more simply, you can get a PDF 'picture' of the grid data, if you wish. The greyscale colour ramp is preserved, which means that the image can be easily altered and manipulated in design software.

Geo-coordinates for grid data

 Geo-coordinates for grid data are 'pixel-is-area', which means that they are at the top-left pixel. 

Non-supported export formats

We do not at present support grid exports to KML or DWG formats.