Raster Manager Overview
The Raster Manager utility allows you to control and manipulate raster images. The Raster Manager dialog lets you control all aspects of attaching and manipulating raster image files. Many settings controlling raster location, display, and search paths can be found in the Preferences dialog in the Raster Manager category. For a complete list of input formats, look in the Supported Input File Formats table.
Raster attachments are treated as any standard element. They can be displayed between vector elements and they can be placed on a level. To achieve this, a new element has been added, the Raster Frame (type 94), which is generated each time a raster is attached. The old type 90 element also continues to be present and is linked to the new Raster Frame. To preserve compatibility with older versions, when a previous version DGN is opened, a Raster Frame is automatically generated for each type 90 present in the file.
Raster Manager lets you control the display of one or more image files within a DGN file view. Each view may be used to display image files. The names of all attached image files (for all views) are displayed in the Raster Manager dialog.
You can open raster files the same way that you open DGN files, using the File Open dialog.
You cannot have more than one raster file open at a time. If you open a raster file when another one is already open, the first file closes. When a multi-page raster file is opened, all pages of the file are displayed side by side.
Information about the image files is stored with the DGN file. The georeferencing and positioning information is also kept in the raster file header for georeferenced file formats. For non-georeferenced image formats, this information is either written to a location info sister file, or it is simply kept in the image's DGN file attachment. To see if a file is georeferenced, look in the Supported Output File Formats table. When HGR or World File are listed under the Options column, this indicates that the format is non-georeferenced and needs an ASCII text file, known as a sister file or world file to position itself. As for a georeferenced format, the Options column will remain empty. User preference settings are available to specify where the georeferencing information is stored, and to set the priority as to which information source will be used.
Warping, mirroring, and resizing parameters are also stored in the DGN file's raster attachment. If the image is detached, these settings are deleted. For more information, see Moving, Warping and Resizing Image Files. Neither clipping and transparency, nor contrast and brightness settings are exported when an image is resampled. These settings are only kept in the DGN file attachment and are lost if the image is detached.