What's new for raster and image data in ArcGIS 10
Improved raster format support
Starting in ArcGIS 10, all raster format support has been improved. You should not see a change in how your data is handled; it should work as it always has. The main purpose of the improved format support is to overcome many of the limitations of the old format library.
The improved format support enables ArcGIS to read and write out more raster formats. As well, there are more TIFF compressions available when creating a TIFF file.
All new pyramids created are now saved as an OVR file (with the exception of the ERDAS IMAGINE® format). The new OVR files are more flexible since they work with all file formats that allow for pyramids. As well, the OVR files can be compressed so that they do not take up as much disk space.
New mosaic dataset data model
A mosaic dataset is a new geodatabase raster data model. The mosaic dataset is supported in all types of geodatabases (personal, file, and ArcSDE).
A mosaic dataset is a collection of raster datasets (images) stored as a catalog and viewed as a dynamically mosaicked image. The raster datasets can also be viewed individually. These collections can be extremely large both in total file size and number of raster datasets. The raster data is added according to its raster type, which identifies metadata, such as georeferencing, acquisition date, and sensor type, along with a raster format. The raster datasets in a mosaic dataset can remain in their native format on disk or, if required, be loaded into the geodatabase. Mosaic datasets are ideal for distributing data because they can be directly accessed by users and easily served.
A mosaic dataset can be viewed with any license level. To create or edit a mosaic dataset requires an ArcEditor or ArcInfo license. To serve a mosaic dataset using ArcGIS Server requires the Image Extension license.
Image Analysis window
The Image Analysis window is a new dockable window that can be used to quickly perform many display and processing raster tasks. It can be added to ArcMap from the Window menu.
Many of the display options on this window existed in ArcMap but were located on various dialog boxes; various options can now be quickly accessed, such as contrast, brightness, transparency, gamma stretch, dynamic range adjustment, ignore background value, contrast stretch, display resampling method, zoom to raster resolution, swipe, and flicker.
This window also contains many processing options, some of which can also be performed using geoprocessing tools. When accessed using this window, they are added to a new layer using functions, including clipping, masking, combining bands, NDVI, pan-sharpening, hillshading, and mosaicking.
Color Correction window for mosaic datasets
When you have a mosaic dataset that needs color correction, the Color Correction window can assist you in performing the color correction task. This window provides many options to color balance your mosaic dataset. The Exclude Area option can be especially helpful for areas that are difficult to color balance, such as water or clouds. The Mosaic Color Correction window button can be added to any toolbar in the Customize Mode.
Color correcting raster catalogs
The Color Correction tab on the raster catalog layer properties dialog box provides additional color correction options. Some of the new parameters available to you include prestretching, more color balancing methods, the ability to specify a color balancing target surface type, and the ability to specify a color balancing reference target image.
There are many new geoprocessing tools available for raster data. The majority of the new tools are for the new raster data model—mosaic dataset. The Mosaic Dataset toolset consists of geoprocessing tools to author, edit, and optimize your mosaic dataset.
The Split Raster tool allows you to take a large raster dataset and divide it into many equal tiles. Similarly, the Raster to DTED tool allows you to divide up your raster dataset according to DTED level 0, 1, and 2 specifications.
The Build Pyramids And Statistics tool allows you to build pyramids and calculate statistics on an entire workspace, using only one geoprocessing tool. The tool also gives you options to only batch build pyramids or batch calculate statistics.
The Make Mosaic Layer tool allows you to create temporary layers, so you can work a mosaic dataset, such as defining a subset of bands as the input for another geoprocessing tool.
There are two tools that have been improved at ArcGIS 10: Mosaic To New Raster and Add Colormap. The Mosaic To New Raster tool is no longer a script tool but a system tool. Making the Mosaic To New Raster a system tool solved a lot of the bugs that existed in the previous script tool. The Add Colormap tool has been enhanced by allowing users to specify .clr and .act files for the color scheme for the raster dataset.
There are two new Environment Settings available within the Raster Storage Options: pyramid compression type and more TIFF compression types. Now, when you build pyramids, you have the ability to compress your OVR files. When you create a TIFF output, you now have more compression types available for your output.
Create a custom CLR file
One of the most requested enhancements has been the ability to create your own colormaps. ArcGIS now allows you to create a custom color scheme within the Unique Values renderer dialog box and save it to a CLR file. Once you have a CLR file created, you can use it with the Add Colormap geoprocessing tool to add the color scheme to your raster dataset.
Advanced labeling with the stretched renderer
The stretched renderer has the option to perform advanced labeling. This allows you to specify values on the color ramp that you would like to display. In addition, you can set up an advanced color ramp between each of the specified values.
Functions allow you to perform dynamic processing to your mosaic datasets and on raster dataset layers (added using the Image Analysis window). Functions can be chained together, allowing you to add multiple processes to your mosaic dataset or raster dataset layer. They are applied from the bottom up.
There are four tabs on the Raster tab of the ArcMap Options dialog box: Raster Dataset, Raster Catalog, Raster Layer, and Mosaic Dataset.
The Raster Dataset tab defines defaults for displaying raster datasets; this tab was previously named General. There is a new check box on this tab, allowing you to Create tiled TIFF files. As well, the raster attribute table limit has been moved to this location.
The Raster Catalog tab defines defaults for displaying raster catalogs. There is a new option called Maximum number of rasters to be drawn. This option limits the number of raster catalog items that will be drawn, so that it will not draw all the items of a large catalog. The Maximum number of rasters for color matching text box has been moved to this tab.
The Raster Layer tab defines the symbology defaults for displaying raster datasets. This is a new tab containing options for the default ignore background value, the NoData color, whether to display datasets with contrast stretching, and the default resampling method.
The Mosaic Dataset tab defines the default settings for displaying mosaic datasets. This new tab presents the option to expand the mosaic dataset in the table of contents. The expanded mode shows the boundary, footprint, and image layers. Options for boundary, footprint, and image layer visibility are also set in this tab.
As with all other aspects of ArcGIS 10, all the raster data icons have been updated. There are new icons for raster datasets, raster catalogs, and the mosaic dataset. Depending on where the raster resides, it will be a specific color. File-based data is yellow, geodatabase data is gray, and data on the server is blue.
Accelerating a raster layer greatly increases the layer's display performance. When you display a raster layer using the accelerated renderer, you can seamlessly pan and zoom around the data in the display. A key feature of the accelerated renderer is the ability to take advantage of graphics card processing units to further enhance performance.
You can accelerate a raster layer via the Image Analysis window.
Serve mosaic datasets
Mosaic datasets are a new dataset that can be served as an image service or inside a globe or map service. There are also additional capabilities to query and interact with image services derived from mosaic datasets.
Enhanced image service parameters
The image service properties page now allows you to control a greater number of default service parameters. This gives you more control over the amount of data a user can request, the type of information that can be requested, and the allowable mosaic and compression methods.
- Maximum image size per request
- Maximum number of rasters per mosaic
- Default resampling method
- Allowed compressions
- Allowed mosaic methods
- Maximum number of records returned per request
- Metadata level
- Allowed fields
- Maximum number of downloads per request
New supported operations
The image service resource has been improved to provide additional operations. Export Image has been improved to allow you to specify mosaic rules and properties. Additionally, Query, Identify, and Download have been added.