Symbolizing values of NoData in raster datasets
Every cell location in a raster has a value assigned to it. A cell is assigned the NoData value if there is either no information or insufficient information about the characteristics of the location it represents. Be aware that NoData and 0 are not the same, because 0 is a valid value.
NoData is stored natively inside the ESRI Grid format. However, this concept of pixels with value-based NoData is foreign to most other raster formats. Because ArcGIS treats nongrid raster formats the same as grids, NoData is allowed in any supported raster format. Most commonly, NoData becomes present in nongrid formats when you update one of these rasters' georeferencing information with the Update Georeferencing menu command on the Georeferencing toolbar. Changing a raster's geographic location often involves rotation, and when a raster is rotated, wedge-shaped areas are created. The wedges are not filled with data and are unknown, so these areas become NoData. With nongrid formats, the areas of NoData are stored in the auxiliary file (.aux) next to the raster itself.
By default, values of NoData are displayed as transparent.
- Add the raster layer with values of NoData to ArcMap.
- Right-click the raster layer and click Properties.
- Click the Symbology tab.
- Click the Display NoData as drop-down arrow and choose a color to display values of NoData.
- Click OK.