Mosaic dataset properties
There are two sections of properties for a mosaic dataset. The general properties are similar to those you find for all raster datasets, such as the data source, extent, cell sizes, and bit depth. For more information on the general properties, see Raster dataset properties. There are also properties specific to the mosaic dataset that include all the nonraster dataset-specific information. These properties can be set by the author of the mosaic dataset, and if the mosaic dataset is served, the server administrator can also modify these properties. Some properties can be set by the client; however, they will only affect the mosaic on their display.
You can access the Mosaic Dataset Properties dialog box via the Catalog window or in ArcCatalog by right-clicking the mosaic dataset and clicking Properties.
The properties on the Default tab are specific to the mosaic dataset. These properties affect how the mosaicked image will be presented to the user (or client) and how they might interact with it. They can also impact the performance of the server or image service if the mosaic dataset is served. You can edit the values in the dialog box by clicking the value next to the property. You will either be able to type in a different value or make a selection from a list.
The mosaicked image properties include
- Maximum Size Of Requests—This property only applies when the mosaic dataset is published and accessed as an image service. The maximum number of rows and columns each time a mosaicked image is generated. By increasing these numbers, you will be increasing the time it takes to process the mosaicked image. However, you may want to increase these numbers if you are printing very large, high-resolution plots. By making these numbers too small, no mosaicked image may display. For example, if you changed the numbers to 10, then the display window could only be 10 pixels in dimension or smaller to display an image.
- Transmission Compression Settings—Defines the method of compression used to transmit the mosaicked raster data from the server to the client. This property affects an image service generated from the mosaic dataset. If accessing the image service over a LAN, large data volumes do not cause a problem. However, when working over slower connections on the Internet, it would be better to apply a compression to the imagery before transmission. This compression reduces the size of transmitted imagery but puts an additional load on the server to compress the data first. This can be altered by the client.
- None—Results in no compression being applied to the imagery, providing the highest quality, but results in the maximum data transfer across the network.
- JPEG—An efficient compression method that can often compress imagery by about three to eight times with little degradation in the image quality. When using this method, a compression quality can also be set between 1 and 100 percent. A value of 80 tends to retain image quality while providing approximately 8x compression.
- LZ77—An efficient, lossless compression method that is often used for imagery with similar pixels such as scanned maps or classification results. This is recommended for discrete data.
- Default Resampling Method—Defines the default sampling method of the pixels, which are sampled to match the resolution of the user's display (or client request if served). Depending on the use or input of the image, the sampling method can be changed. More accurate radiometry values are obtained using nearest neighbor sampling. This is generally faster but can result in jagged edges of features. Bilinear interpolation provides smoother images but can result in some smoothing of the image. Bilinear is recommended for continuous raster data. Cubic convolution is geometrically more accurate but slightly slower than bilinear interpolation. Majority is best applied to discrete data. The user can choose to change this selection.
- Maximum Number Of Rasters Per Mosaic—Prevents the server from mosaicking an unreasonably large number of rasters if, for example, the client zooms in to an overview scale in an nonoptimized image service dataset that has no overview tiles generated. The default is 20.
- Allowed Mosaic Methods—Defines the order of the rasters that are mosaicked together to create the image. You can choose one or more mosaic methods and which one will be the default. The user is able to choose from the methods you select.
- Closest to Center—Enables rasters to be sorted based on a default order where rasters that have their centers closest to the view center are placed on top.
- Closest to Nadir—Enables rasters to be sorted by the distance between the nadir position and view center. This is similar to the Closest to Center method but uses the nadir point to a raster, which may be different than the center, especially for oblique imagery.
- Closest to Viewpoint—Orders rasters based on a user-defined location and nadir location for the rasters using the Viewpoint tool.
- By Attribute—Enables raster ordering based on a defined metadata attribute and its difference from a base value.
- North-West—Enables raster ordering in a view-independent way, where rasters with their centers to the northwest are displayed on top.
- Seamline—Cuts the raster using the predefined seamline shape for each raster using optional feathering along the seams and orders images based on the SOrder field in the attribute table.
- Lock Raster—Enables a user to lock the display of single or multiple rasters based on the ObjectID.
- None—Orders rasters based on the order (ObjectID) in the mosaic dataset attribute table.
- Viewpoint Settings—When the Closest to Viewpoint mosaic method is used, these setting will be applied:
- Viewpoint x and y spacing—Defines an offset that is used to calculate where the center of the area of interest (display view) is when you click an arrow button on the Viewpoint dialog box. These values are calculated in the units of the spatial reference system of the mosaic dataset.
- Always Clip The Image To Its Footprint—You can choose to limit the image extent to its footprint or not.
- Apply Color Correction—If there is a color correction method in place for the mosaic dataset, you can choose to apply it when using the Closest to Viewpoint mosaic method.
- Is Processed Data—When a mosaic dataset is displayed in ArcMap or ArcGlobe, the default settings for the renderer are applied, such as a standard deviation stretch. These defaults will be applied when this value is NO. However, if you've authored a mosaic dataset to appear a particular way and you don't want the stretch or other things altered, then set this value to YES. YES ensures that your mosaic dataset is processing the data the way you want it to appear.
- Raster Metadata Level—Defines how much metadata will be transmitted from the server to the client. This can affect the transmission time when there is a lot of metadata to transmit; therefore, you may choose to limit it. The options are
- Full—The basic raster dataset information and the function chain's details will be transmitted. This is the default.
- Basic—The raster dataset level of information will be transmitted, such as the columns and rows, cell size, and spatial reference information.
- None—No metadata will be transmitted.
- Maximum Number Of Records Returned Per Request—Limits the requested number of records that will be returned by the server when viewing the mosaic dataset as a published image service.
- Allowed Fields—Defines which fields from the attribute table will be visible to the client when the mosaic dataset is served.
Time—If the mosaic dataset contains attribute fields that define time, you can create a mosaic dataset that will automatically be time aware, meaning the time properties in the layer will be defined by default. You can define the field for the start time and end time and the time format. It is recommended that you store time values in a date field; however, string and numeric fields are also supported.
- Geographic Coordinate System Transformation—If the spatial reference system of the mosaic dataset is based on a different spheroid than the spatial reference system of the source raster data, then you may need to specify a specific geographic transformation. This parameter gives you access to a dialog to help you pick the geographic transformation.
- Maximum number of items downloadable per request—Limits the number of rasters that a client can download from an image service. You may want to set this to 0 if you do not want a client to download any rasters from within your mosaic dataset. Optionally, this value can affect the load. You may want to adjust this number depending on how you want clients to use their image services.
Note:Source files stored using the GRID raster format cannot be downloaded.
When publishing a mosaic dataset using ArcGIS Server, the server administrator can modify some of these properties; however, they will not be able to exceed the maximums you have set. For example, If you limit the allowed mosaic methods to only three of the methods, the administrator will not be able to add a fourth method. Or, if you set the maximum number of downloadable items, they can reduce the number but not increase this number.
If you change the properties to exceed or limit a value, such as the Maximum Size Of Requests, you need to completely republish the mosaic dataset. If you restart the image service, the changed properties in the mosaic dataset will not be picked up.