ILWIS objects

 

Representations    

 

 

A representation defines the manner in which classes of a map with a class domain, a group domain or a picture domain, or the values of a map with a value domain or the image domain should be represented on the screen and on a printer.

A representation stores colors or ranges of colors for the classes in a class domain, or for specific values or ranges of values for the values in a value domain. Furthermore, for polygon classes, colors, hatching and patterns can be stored; for segment classes, colors, line types and line widths, etc. can be stored; and for point classes, colors, symbols, symbol sizes, etc. can be stored.

A representation is a service object for a domain, i.e. a domain uses a certain representation.

Maps with a Bool, the Bit, an ID, or the Color domain do not have a stored representation on disk:

Furthermore, special options for point symbols available in the Display Options dialog box of a point map.

Tip:

You can always create a number of representations for a certain domain, for instance by clicking the create button next to the Representation list box in the Display Options dialog box of a map. When you already have a number of representations, you can also select a suitable one in the map's Display Options dialog box.

Types of representations:

There are three types of representations:

Link between domains and representations:

A representation is linked to a domain. The domain of a map thus knows the default representation when the map is displayed. Furthermore, this ensures that:

 

The default representation for a domain can be viewed in the Properties of a domain.

 

Tips: You can always create/select other representations that fit the domain of a map:

     

  1. For maps that use a Class domain:
  2.  

  3. For maps that use a user-defined value domain:
  4.  

  5. For maps that use a system value domain:

Finally, to permanently link a certain representation to a certain user-defined domain, you can make the domain read-only in the Domain Properties.

Names of representations:

In ILWIS 3, object names comply with Windows long file names. Also Universal Naming Convention (UNC) paths are supported. For more information, see How to use long object names.

To create a representation:

1. Creating a representation class:

When creating a new class or group domain, a representation class is automatically created with default colors; these can of course be edited.

The easiest way to create another representation class for a map with a class, group or picture domain, is to click the create button in the Display Options dialog box of the map. Then, through the Create Representation dialog box, a new representation class will be created for the domain that is used by the map. Subsequently, the Representation Class editor will be opened.

In the Representation Class editor, choose whether you want to adapt the representation for the raster form, the polygon form, the segment form or the point form. Then, edit the colors, etc. of each class for instance by double-clicking individual classes. You can also select multiple classes and choose Edit Multiple Items from the Edit menu to assign one color or a smooth range of colors to the selected classes.

2. Creating a representation value:

When creating a new value domain, a representation value is not automatically created. You can always show a map with a value domain with an existing representation gradual, e.g. Pseudo.

The easiest way to create a representation value for a map with a value domain is to click the create button in the Display Options dialog box of the map. Then, through the Create Representation dialog box, a new representation value will be created for the domain that is used by the map. (For maps which use system domain Value, you can clear the Use Percentages check box in the Create Representation dialog box to create a representation value.) Subsequently, the Representation Value editor will be opened.

In the Representation Value editor, you can insert limits, i.e. boundary values for a representation value, you can choose or create a color for each limit, and you can indicate whether to stretch between the limits or to use the color of the upper of lower boundary.

3. Creating a representation gradual:

When you click the create button in the Display Options dialog box of a map which uses system domain Value, and when, in the Create Representation dialog box, you select the Use Percentages check box, a new representation gradual will be created with default colors. The Representation Gradual editor is opened.

In the Representation Gradual editor, you can insert limits, i.e. boundary percentages for a representation gradual, you can choose or create a color for each limit, and you can indicate whether to stretch between the limits or to use the color of the upper of lower boundary.

Tip:

When a map (e.g. Map1) is currently using system domain Value, but when a more clearly defined value domain would be more appropriate, for instance because a user-defined value domain can have a certain default representation value (which will ensure that the map will by default display in 'correct colors'), you have to change the domain of the map with system domain Value to a user-defined domain:

For more information, see How to change the domain of a map.

4. Other ways to create representations:

Furthermore, you can create a representation through the File menu of the Main window, by double-clicking the New Representation item in the Operation-list, or via the Properties dialog box of a domain. For more information, see How to create a representation.

To view and edit a representation:

To edit an existing representation, you can for instance double-click a representation in the Catalog. When a map is displayed in a map window, you can also open the Edit menu in the map window and choose Representation. Depending on the type of representation you selected, the Representation Class editor or the Representation Value/Gradual editor is opened. For more information, see How to edit a representation or the respective editors.

Advanced users may wish to open and/or edit a representation class as a table. For more information, see How to open objects as a table. System representations and read-only representations cannot be edited.

Technical information:

A representation consists of an ASCII object definition file (.RPR); in case of a representation class also a binary data file (.RP#) is available. The object definition file has no further references to other objects.

By viewing the properties of a representation, you can see for instance the type of the representation and you can find out to which domain the representation is linked. A representation is a property of a domain.

A representation class stores, for each class in the domain:

Advanced users may wish to open and edit a representation class as a table.

A representation gradual stores:

A representation value stores:

System representations:

The following system representations are representations gradual:

Blue

From black to blue in 16 stretch steps.

Clrstp6

Six times from black to a color (6 colors between blue to red), each time in 8 stretch steps.

Clrstp8

Eight times from black to a color (8 colors between blue to red), each time in 8 stretch steps.

Clrstp10

Ten times from black to a color (10 colors between blue to red), each time in 8 stretch steps.

Clrstp12

Twelve times from black to a color (12 colors between blue to red), each time in 8 stretch steps.

Cyan

From black to cyan in 16 stretch steps.

FineGray

From black to white in 60 stretch steps.

Gray

From black to white in 30 stretch steps.

Default representation for system domain Image, and for the system domains Byte, Count, Min1to1, NOAA, Perc and Radar.

Green

From black to green in 16 stretch steps.

Inverse

From white to black in 30 stretch steps.

Magenta

From black to magenta in 16 stretch steps.

Pseudo

From blue to green to red in 6 x 9 stretch steps.

Default representation for system domain Value and system domain Distance.

Red

From black to red in 16 stretch steps.

Yellow

From black to yellow in 16 stretch steps.

The following system representation is a representation value:

NILto1

Designed for SMCE standardized maps that have values between 0.00 and 1.00;

  • from red (0.00) to yellow (0.50) in 10 stretch steps, and
  • from yellow (0.50) to green (1.00) in 10 stretch steps.

Default representation for system domain NILto1.

The following system representations are representations class:

ColorCmp

Designed for output raster maps of the Color Composite operation created with the Standard option; 216 colors.

FlowDirection

Designed to display the eight compass directions N, NE, E, SE, S, SW, W, NW, W; default representation for maps using system domain FlowDirection.

Output maps of the Flow Direction operation always use system domain FlowDirection and are therefore by default displayed with the FlowDirection representation.

Note:

System representations cannot be edited, but you can always create a new representation, for instance by clicking the Create button next to the Representation entry in a map's Display Options dialog box. For more information, see sections 2 and 3 on creating representations above.

See also: