Working with the Footprint layer

Legacy:

ArcGIS 10 is the last release of the stand-alone ArcGIS Image Server product. The image service definition (.ISDef) has been replaced by an improved geodatabase data model—the mosaic dataset—which can be published as an image service using the ArcGIS Server Image extension.

The Footprint layer displays the footprints that define the extent of the pixels in each raster dataset. This layer will be displayed using the coordinate system of the data view. The Footprint layer is not always the extent of each raster dataset, but it can be the extent of the valid raster data within the datasets. By default, when a raster dataset is added to the image service definition, the footprint is drawn to the known extent of the pixels. For most raster datasets, this will be a rectangle, but it may also be other shapes. Each raster dataset is clipped by the server to its footprint. The footprint can be modified using standard ArcMap editing tools or recomputing footprint features. To learn more about footprints, see About the image service definition file.

By default, a footprint is displayed as a green hollow polygon, but the symbology can be changed using the standard ArcMap layer symbology properties.

When you right-click the Footprint layer, the following context menu appears:

Many of the commands on this context menu are standard ArcGIS menu layer options. Open Attribute Table, Joins and Relates, Zoom To Layer, Visible Scale Range, Use Symbol Levels, Selection, Label Features, Convert Features to Graphics, Export Data, and Properties are standard ArcGIS features. Those options that are specific to ArcGIS Image Server are described below.

Select

Select provides the following options:

• By Pixel Size—Enables selection of rasters based on their pixel size or range of pixel sizes. This feature can be used to either globally select a set of rasters with a specified range of pixel sizes or reduce a selection set to a specified range. A dialog box is displayed that is used to create a query to select the required rasters.
  Select By Pixel Size dialog box

  Parameter	Description
  Field	In ArcGIS Image Server, there are four different pixel sizes—Lo, Hi, Min, and Max—and two pixel size ranges (Low-High and Min-Max). To learn about the pixel size ranges, see Working with the service table.
  Pixel Size	Enables you to select the required pixel size. The drop-down list displays the currently available pixel sizes. The default is the pixel size in meters corresponding to the current data frame scale.
  Tolerance	Defines the range of pixel sizes to be selected based on the percentage difference to the specified pixel size. When you enter 0, only the specified pixel size is selected. For example, when you enter a value of 50%, you can select rasters whose pixel size is up to 50 percent larger or smaller than the specified value.
  Method	Defines when you Create a new selection—The existing selection set is cleared, and a new selection that contains only the specified query is selected. Add to current selection—The result of the query is added to the existing selection set. Remove from current selection—The result of the query is removed from the existing selection set. Select from current selection—The query is applied to the currently selected rasters. If there is a selection set before applying this feature, the default method will be Select from current selection or Create a new selection.
  Query	This is the query that is applied when you click OK. The query is dynamically modified as the parameters are changed but can also be manually changed if required.

  Select By Pixel Size dialog box
• By Raster Type—Enables the selection of rasters based on their type. This is used to quickly select a service overview or a specific type of raster. A dialog box is displayed that is used to create a query to select the required rasters.
  Select By Raster Type dialog box

  Parameter	Description
  Raster type	Specifies the type of raster. The drop-down list defines the existing raster types.
  Method	Enables the way the selection will be affected.

  Select By Raster Type dialog box
• By Status—Enables the selection of rasters based on their status ID. The status ID is defined for each raster during the build process and is used to indicate when there is an error or warning. A dialog box is displayed that creates a query to select the required rasters.
  Select By Status dialog box

  Parameter	Description
  Status ID	Specifies the status ID
  Method	Enables the way the selection will be affected

  Select By Status dialog box
• By Attribute—Enables the selection of rasters based on different attributes using queries. This is a standard ArcGIS feature.
• As View—Enables the selection of the rasters that are in the view and current pixel size. This simulates the query performed internally if a user zooms to the current view.
• Clear Selection—Clears the selection so that no rasters are selected.

Symbolize

Symbolize provides the following options to change the symbology to allow differentiation of individual or overlapping footprints. These options enable the quick resymbolization of the footprint using various standard symbology that is suitable for determining different aspects of the service with relation to the footprint geometry.

• Symbolize by Pixel Size—Prompts for the pixel size type (Lo, Hi, Min, or Max) and resymbolizes the rasters based on these values. The smaller pixel sizes are drawn in thinner lines, and a standard color ramp is used.
• Symbolize by Type—Resymbolizes the rasters based on the raster type.
• Symbolize by Status—Resymbolizes the rasters based on the status. The status is only recomputed after building the service.
• Symbolize Random—Symbolizes each raster in a different color and assists in differentiation of overlapping rasters.
• Reset—Resets footprint color of the rasters to the default.

Display

Display enables the display of rasters to be restricted so that only specific rasters are shown. This is used to reduce the screen clutter when there are many overlapping rasters. Its functionality is similar to the features available in a layer property definition in ArcGIS. The following options are available:

• By Pixel Size—Similar to Select By Pixel Size but restricts the displayed rasters to those defined
• By Raster Type—Similar to Select By Raster Type but restricts the displayed rasters to those defined
• By Status—Similar to Select By Status but restricts the displayed rasters to those defined
• By Attribute—Similar to Select By Attribute but restricts the displayed rasters to those defined
• Reset To All—Removes display queries such that all rasters are displayed

Recompute Footprint

This feature is used to redefine footprints by considering either the geometry or the radiometry of the raster data. After applying some of the processes on a raster (such as the Ortho process), the original footprint of the raster gets changed and you may have to recompute the footprints based on the current georeferenced raster.

The options for recomputing the footprints on the Footprint context menu are as follows:

• Recompute Footprint By Geometry—Recomputes the geometry of the footprint for each raster based on its current georeferencing

  Learn about recomputing footprints based on geometric corrections

• Recompute Footprint By Radiometry—Recomputes the footprint region for each raster by excluding the invalid data around an image based on a pixel value range

  Learn about recomputing footprints to remove unwanted pixel data

• Recompute Footprint By Clipping To Boundary—Clips the footprint to the extent of the boundary

  Learn about clipping footprint polygons to the image service boundary

• Recompute Footprint By Shrinking—Reduces the size of the footprint of each raster so that the raster edges are not used

  Learn about shrinking footprint polygons

• Recompute Footprint By Related Geometry—Copies the geometry of the footprint for each raster from external tables/layers

  Learn about importing footprint polygons

Generate Seamline

Rasters can be mosaicked along seamlines using feathering. Various methods are available for defining and editing seamlines.

Generate Seamline provides the following options:

• By Radiometry—Creates seamline polygons that are unique for each raster dataset and are generated by comparing the overlap between raster datasets and intelligently creating a seamline to follow natural patterns between the overlap.
  Generate Seamlines By Radiometry dialog box

  Parameter	Description
  Seamline granularity	Pixel size, measured in meters, that will be used when generating the seamline
  Feather width	Pixel blending, measured in meters, that will be considered when generating seamlines

  Generate Seamlines By Radiometry dialog box
• By Exporting Footprints—Enables the export of a footprint as a seamline. If the export of a footprint to a seamline overrides an existing seamline, a warning is displayed and the existing seamlines that will be overwritten are selected.