The Preferences Dialog

On the left side of the Preferences dialog window you can see a thematical tree where you can select the context of the settings you want to change. In the following example, a screen shot is shown where the settings for the user interface behavior can be edited.

UI Behavior

This preferences page contains general user interface behavior and memory management settings.

• Show navigation window when image views are opened
  If an image view is opened the navigation window will also be opened.
• Open image view for new (virtual) bands
  Currently, this option only affects the band arithmetic tool. If this option is selected, a new image view is automatically created and opened for any new bands created in the band arithmetic tool.
• Show only pixel values of loaded or displayed bands
  If selected, the pixel info view will only show pixel values of bands which have their raster data completely loaded into memory or which are currently displayed as an image. If this option is not selected, DAT displays all bands contained in a product. For those bands which are not loaded, DAT reads the sample values directly from the product file. Depending on your computer's I/O performance and the location of the product file (e.g., CD-ROM, harddrive, network) this can have an impact on DAT's runtime performance.
• On product open, warn if product size exceeds
  If a product being opened has a file size greater than the size put in here, then DAT asks you whether or not you want to create a spectral or spatial subset of this product in order to reduce the required memory.
• On low memory, warn if free RAM falls below
  Here you can enter a value in megabytes, which uses DAT to decide to pop-up a low memory message box. Set this value to zero, if you don't want to get any warnings.
• On image open, load raster data only if size is below
  The value entered here is the number of megabytes a band's raster can have so that it is completely loaded into memory before the image is displayed. If raster data is completely loaded into memory, DAT can perform many computations much faster. If you set this value to zero, DAT will never load and store raster data in memory for image creation and will reload missing raster data from the product file any time it needs it.
• Un-load raster data when closing images
  In order to display images, DAT holds a raster data buffer which contains the geophysical measurement values for the tie point grid or band being displayed. Depending on the product size, these buffers require huge amounts of memory. After these buffers have been un-loaded and an image view is opened again for the same band, DAT needs to reallocate the buffer memory and to read the data from disk again.
• Check for new version on DAT start
  Checks on application start, if a new version of DAT is available.
• Show all suppressed tips and messages again
  Some dialogs of DAT can be disabled by checking the option "Don't show this message again". You can select this option to enable all messages and tip dialog boxes again.

UI Appearance

• UI Font:
  Sets DAT user interface font name and size.
• UI Look and Feel:
  Lets you select the appearance (Look and Feel) of the user interface of DAT.

Product Settings

• Consider products as spatially compatible, if their geo-locations differ less than
  This value affects the product compatibility check performed by the band arithmetic tool. The check is performed in order to decide which bands from which products can be used as data source in a band arithmetic expression. The value must be given in degrees. Use small values, e.g., 0.0001 degrees, to perform a high accuracy check. This will ensure that products completely overlap each other in space.

Geo-location Display

DAT uses an image coordinate system whose origin (x=0, y=0) is the upper left corner of the upper left pixel. Image X-coordinates increase to the right, Y-values increase downwards. The center of the pixel in the origin is then located at (x=0.5, y=0.5).

• Relative pixel-X/Y offset
  Defines a relative offset used to display image coordinates and associated geo-location information. Note that the offset is exclusively used for coordinate value display; it does not affect the geo-coding information associated with a data product.
• Show floating-point image coordinates
  Select this option to display image coordinates as floating point values, e.g., in the geo-location section of the pixel info view. If not selected, image coordinates are displayed as integer values.

Data Input/Output

• Save product header (MPH, SPH)
  This option allows you to include/exclude the main product header (MPH) and specific product header (SPH) of ENVISAT products in/from the file being saved. If this option is selected, DAT stores the MPH and SPH as meta-data in the BEAM-DIMAP (XML) header.
  It is recommended to always include this meta data.
• Save product history (History)
  This option switches the saving of the processing history of the product on or off. It is recommended to always include this meta data to be able to track the processing stages and the original product.
• Save product annotation data sets (ADS)
  This option allows you to include/exclude all annotation data sets (ADS) of ENVISAT products in/from the file being saved. If this option is selected, DAT stores ADS as meta-data in the BEAM-DIMAP (XML) header.
  For ENVISAT products, location and annotation data sets (provided at tie-points) need not to be stored as meta data, since DAT automatically converts them into tie point grids, which are separately saved.
• Use incremental Save
  If this option is selected (recommended), DAT will only save the modifications applied to a product, such as bands modified or created with band arithmetic tool or the removal of bands. Otherwise, a save operation will always write the entire product. 

Layer Properties ->

• Use anti-aliasing for rendering text and vector graphics
  If this option is selected, DAT uses anti-aliasing to smooth vector graphics within image views.

Image Display

• Interpolation method
  Here you can choose how neighbouring pixel colours are interpolated. Choose
  • Nearest Neighbour to prevent colours from being mixed,
  • Bi-linear or Bi-Cubic to smooth the image.

Note: choosing other than Nearest Neighbour may slow down image handling. But: on Mac OS X, Bi-linear is the System Default and therefore fastest.

• Tile cache capacity
  The amount of memory the image tile cache can allocate. Allocating more memory can improve the speed of the image processing.

• Background colour
  Choose a background colour for the image displayed in the image view.
• Show image border
  Here you can specify if an image border should be visible in the image view. If yes, you can also set the border size and colour.
• Show pixel border in magnified views
  Define whether a border should be drawn around a pixel under magnification when the mouse cursor points at it.

No-data overlay

This preferences page provides options to customize DAT's no-data overlay.

• Color:
  Sets the fill colour of a ROI.
• Transparency:
  Sets the transparency of a filled ROI.

Graticule Overlay

This preferences page provides options to customize DAT's graticule overlay.

• Grid behaviour:
  • Compute latitude and longitude steps
    The step size of the grid lines will be computed automatically.
  • Average grid size in pixels
    Defines the size in pixels of the grid cells.
  • Latitude step (dec. degree):
    Sets the grid latitude step in decimal degrees.
  • Longitude step (dec. degree):
    Sets the grid longitude step in decimal degrees.
• Line appearance:
  • Line colour:
    Sets the colour of the grid lines.
  • Line width:
    Sets the width of the grid lines.
  • line transparency:
    Sets the transparency of the grid lines.
• Text appearance:
  • Show text labels:
    Sets the visibility of the text labels.
  • Text foreground colour:
    Sets the colour of the graticule text (latitude and longitude values).
  • Text background colour:
    Sets the background colour of the graticule text (latitude and longitude values).
  • Text background transparency:
    Sets the transparency of the background colour of the graticule text.

Pin Overlay

This preferences page provides options to customize DAT's pin overlay.

• Show text labels:
  Shows the labels of the displayed pins.
• Text foreground layer:
  Sets the foreground colour of the labels.
• Text background layer:
  Sets the background colour for the labels.
• Text background transparency:
  Sets the transparency of the background for the labels.

GCP Overlay

This preferences page provides options to customize DAT's GCP overlay.

• Show text labels:
  Shows the labels of the displayed GCPs.
• Text foreground layer:
  Sets the foreground colour of the labels.
• Text background layer:
  Sets the background colour for the labels.
• Text background transparency:
  Sets the transparency of the background for the labels.

Shape Figure Overlay

This preferences page provides options to customize DAT's shape overlay.

• Outline appearance:
  • Outline shape
    If selected, the outline of a ROI is also drawn.
  • Shape outline colour:
    Sets the colour of a shape's outline.
  • Shape outline transparency:
    Sets the transparency of a shape's outline. Low values produce high coverage.
  • Shape outline width:
    Sets the width of a ROI's outline.
• Fill appearance:
  • Fill shape
    If selected, the shape area is also drawn.
  • Shape fill colour:
    Sets the colour of a shape's area.
  • Shape fill transparency:
    Sets the transparency of a shape's area. Low values produce high coverage.

ROI Overlay

This preferences page provides options to customize DAT's ROI overlay.

• Color:
  Sets the fill colour of a ROI.
• Transparency:
  Sets the transparency of a filled ROI.

RGB Profiles

This preference page is used to edit the RGB profiles used for RGB image creation from various product types. A RGB-Profile defines the arithmetical band expressions to be used for the red, green and blue components of an RGB image. For detailed information about RGB-Profiles please refer to the chapter RGB-Image Profile located at DAT/Tools/Imaging Tools

• Use the to open a stored RGB-Profile file.
• Use the to save the currently displayed RGB-Profile.
• Use the to delete the currently displayed RGB-Profile.

• Red - Defines the arithmetical expression for the red channel.
  
• Green - Defines the arithmetical expression for the green channel.
  
• Blue - Defines the arithmetical expression for the blue channel.
  

Use the to edit the expression for the specific channel by using the expression editor.

Note: The arithmetical expressions are not validated by DAT; keep careful to use the correct syntax.
Please refer to the Arithmetic Expression Editor documentation for the syntax and capabilities of expressions.

Logging

This preferences page provides options to customize DAT's logging behavior.

• Enable logging
  If this option is selected, DAT writes a log file which can be used to reconstruct user interactions and to trace system failures.
• Log filename prefix:
  Here you can enter a prefix for the log file name. The disk file name will be assembled using this prefix plus a log file version number and an identification number. Log files are always written in the folder log located in the Toolbox user directory. Under windows, this folder would be c:\Document and Settings\user\.nest\. Under Linux, this folder would be /home/user/.nest/.
• Echo log output (effective only with console)
  If DAT is started with a text console window using the %SNAP_HOME%/DAT.bat (Windows) or $SNAP_HOME/DAT.sh (Linux) scripts, the log file entries are also printed out to the console window.
• Log extra debugging information
  Sets DAT into the debugging mode which can be helpful to find software bugs.