Mask segments

Functionality

The Mask Segments operation allows you to selectively copy segments of an input segment map into a new segment map. The user has to specify a mask to select and retrieve the class names, identifiers or values of segments that are to be copied.

By specifying a mask, you can search for segments with a certain class name, ID or value. A mask is in fact a simple query to find (retrieve), display or use only those segments in a map that have certain class names, identifiers or values. A mask contains one or more search strings in which wild cards, asterisks (*) and question marks (?), are allowed. You can enter as many search strings in a mask as you like; separate the strings by commas.

Mask syntax:

search strings in a mask are compared with the classes, IDs or values of the domain of a map; when a map uses a class or ID domain and the classes or IDs have codes, the mask works on the codes and on the names and on the combination of codes and names,
to find/retrieve one specific class name, identifier or value: type that class name, ID or identifier in the mask,
to find/retrieve multiple class names, identifiers or values: separate the different class names, identifiers or values in the mask by commas (it does not matter whether you use spaces before or after a comma)
you can use asterisks as wild cards to replace zero or more characters in class names, IDs or values, for example road*,riv* or 1*,2*,3* , or even *25,*50,*75,*00, or A*b*,D*g*
you can use question marks as wild cards to replace single characters in class names, identifiers or values, for example Ab?,D?,Gl? or ?p,??i, or A*b??,D*g??
in a dialog box, you should not use quotes around class names, identifiers or values,
on the command line, you must use double quotes around the complete mask.

Examples:

When a segment map contains topographic features, and you want to copy the segments with class names 'river' and 'road'; use as mask: river,road
When a segment map contains pipe lines identified by IDs between 1000 and 9999, and you want to copy the segments with an ID that starts with a 1, e.g. IDs 1001, 1002, 1003, etc.; use as mask: 1*
When a segment map contains height values between 0 and 5000m, and you want to copy the segments with a height value between 1000 and 1500; use as mask: 10*,11*,12*,13*,14*,1500

For more information, see How to use masks.

Requirements for input segment map:

No special input map requirements.

Domain and coordinate system of output map:

The output segment map uses the same domain as the input segment map.

The output segment map uses the same coordinate system and coordinate boundaries as the input segment map.

Tips:

This operation creates a new segment map. You can also display specific segments of a segment map in a map window without creating a new segment map: select the Mask check box on the Display Options dialog box of the segment map which appears when you open the segment map. Then, specify the mask, i.e. the class names, identifiers or values of the segments that you want to display.
To copy a certain area of a segment map into a new segment map, see Sub-map of segment map.
To combine two or more segment maps, see Glue segment maps.