On-the-Fly Mosaicking Continued from page 9 Follow these steps to create a mosaic dataset 1. Create or locate a target geodatabase. If ArcSDE is not required, using a file geodatabase is recommended. 2. In ArcCatalog, right-click the geodatabase and choose New > Mosaic Dataset. 3. Specify the mosaic dataset name. 4. Specify the coordinate system that will be used for managing the mosaic dataset. Rasters may be in any spatial reference system. 5. Add rasters to the mosaic dataset. 6. Specify raster type in the Raster Type Properties dialog box. As raster datasets are added to the mosaic dataset, footprints are created for each raster dataset and the boundary is generated for the entire mosaic dataset. The overviews are generated for the entire mosaic dataset and are generally small when compared to the complete dataset. Instead of creating overviews, you can use other lower-resolution imagery if available or another imagery source such as ArcGIS online. 7. Optionally, expand Advanced Options and (if necessary) check the option to Build Raster Pyramids and Calculate Statistics, if necessary. Set the properties that affect how the mosaicked image will be presented to the client and how they can interact. 8. Right-click on the mosaic dataset in the catalog window to open the Mosaic Dataset Properties dialog box. From the Defaults tab, you can change default properties such as the compression method used for transmission, the default resampling method, and the default mosaic method. These properties are used when a mosaic dataset is accessed but can be changed by users depending on their requirements. From the Functions tab, you can add additional image processing functions that will be applied to the mosaic. These are functions applied to the image after it is mosaicked from multiple sources but before it is displayed. When done, the mosaic dataset is added to the table of contents and can now be used. The functions associated with each raster can also be modified (if required). Raster data is added to a mosaic dataset by specifying a raster type. Raster Types Raster data is added to a mosaic dataset by specifying a raster type. Raster dataset, the default raster type, can be used for all standardized data sources such as GeoTIFF or MrSID files. The raster type can be used to facilitate the use of more complex data and identifies metadata, such as the acquisition date and sensor type, along with a raster format and optional additional processing to be applied to the rasters. Raster types can be easily customized and stored for future use to help automate adding similar data. Image 1 Image 3 Image 2 Image 4 A mosaic dataset consists of a catalog that provides the source of the pixels, properties, metadata, processing functions, and footprints of the participating rasters; includes a feature class that defines the boundary; and applies mosaicking rules that define the default rules for dynamically mosaicking overlapping rasters. 10 ArcUser Summer 2010 www.esri.com