Importing and Exporting

Producer Field Guide

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Producer Field Guide
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Producer

Raster Data

There is an abundance of data available for use in GIS today. In addition to satellite and airborne imagery, raster data sources include digital x-rays, sonar, microscopic imagery, video digitized data, and many other sources.

Because of the wide variety of data formats, ERDAS IMAGINE provides two options for importing data:

  • import for specific formats
  • standard import for general formats

Import

Many raster data formats can be imported to, exported from, directly read from, and directly written to ERDAS Desktop and Server products.

There is a distinct difference between import and direct read. Import means that data is converted from its original format into another format (for example, DEM or TIFF), which can be read directly by ERDAS IMAGINE. Direct read formats are those formats that the Viewer and many of its associated tools can read immediately without any conversion process.

In ERDAS Desktop, the import function converts raster data to ERDAS IMAGINE file format (.img), or other formats directly writable by ERDAS IMAGINE. The import function imports the data file values that make up the raster image, as well as the ephemeris or additional data inherent to the data structure. For example, when Landsat data is imported, ERDAS IMAGINE also imports georeferencing data for the image.

Each direct function is programmed specifically for that type of data and cannot be used to import other data types.

SHARED Tip Raster data formats cannot be exported to vector data formats unless they are converted with Vector utilities.

See the Help topic for the corresponding ERDAS product to see a list of supported data formats.

Raster Data Sources

NITFS

National Imagery Transmission Format Standard (NITFS) is designed to pack numerous image compositions with complete annotation, text attachments, and imagery-associated metadata.

SHARED Tip Statistics and pyramid layers (.rrd files) are not created in export functions. These files are created when imported into IMAGINE, and export function is used when this data is exported out of IMAGINE. If you need statistics and pyramid layers, use Edit Image Metadata option.

According to Jordan and Beck,

NITFS is an unclassified format that is based on ISO/IEC 12087-5, Basic Image Interchange Format (BIIF). NITFS implementation of BIIF is documented in U.S. Military Standard 2500B, establishing a standard data format for digital imagery and imagery-related products.

NITFS was first introduced in 1990 and was for use by government and intelligence agencies. NITFS is now the standard for military organizations as well as commercial industries.

Jordan and Beck list the following attributes of NITF files:

  • provide a common basis for storage and digital interchange of images and associated data among existing and future systems
  • support interoperability by simultaneously providing a data format for shared access applications while also serving as a standard message format for dissemination of images and associated data (text, symbols, labels) via digital communications
  • require minimal preprocessing and post-processing of transmitted data
  • support variable image sizes and resolution
  • minimize formatting overhead, particularly for those users transmitting only a small amount of data or with limited bandwidth
  • provide universal features and functions without requiring commonality of hardware or proprietary software

Moreover, NITF files support the following:

  • multiple images
  • annotation on images
  • ASCII text files to accompany imagery and annotation
  • metadata to go with imagery, annotation and text

The process of translating NITFS files is a cross-translation process. One system’s internal representation for files and their associated data is processed and put into NITF format. The receiving system reformats the NITF file, and converts it for the receiving systems internal representation of the files and associated data.

IMAGINE NITF software in ERDAS IMAGINE accepts such information and assembles it into one file in standard NITF format.

Source: Jordan and Beck, 1999

Annotation Data

Annotation data can be directly written in ERDAS IMAGINE, as well as importing to annotation from another format and exporting to annotation from another format.

ERDAS IMAGINE can write Annotation layers (*.ovr) and Area of Interest layers (*.aoi). Annotation can also be stored as separate layers in a map composition (*.map).

See the Help topic for the corresponding ERDAS product to see a list of supported data formats.

Generic Binary Data

Generic Binary import option is a flexible program which permits defining the data structure for ERDAS IMAGINE. This program allows import of BIL, BIP, and BSQ data that are stored in left to right, top to bottom row order. Data formats from unsigned 1-bit up to 64-bit floating point can be imported. This program imports only the data file values—it does not import ephemeris data, such as georeferencing information. However, this ephemeris data can be viewed using Data View option.

Complex data cannot be imported using this program; however, they can be imported as two real images and then combined into one complex image using Spatial Modeler.

SHARED Tip You cannot import tiled or compressed data using Generic Binary import option.

Vector Data

Vector layers can be created within ERDAS IMAGINE by digitizing points, lines, and polygons using the computer screen. Several vector data types, which are available from a variety of government agencies and private companies, can be created and edited including shapefile, coverage, personal geodatabase and so forth. These data can then be used for analysis.