Command Help divide-wireframe-by-strings

 

Command Name	Menu	Quick Key	Link to Command Table
divide-wireframe-by-strings	ribbon | Operations | Plane | Divide by Strings	-	Click here

Description

Splits a wireframe into several parts using multiple selected strings.

Note: This command supports flexible wireframe selection.

How to Use

1. Select the strings which are to be used to control the splitting.
    

   Any selected open strings must be able to create intersection planes, when projected in the selected direction, to subdivide the wireframe data completely i.e. they should extend beyond the limits of the wireframe.

2. Run this command.

3. In the Divide Wireframe dialog, select the wireframe object to be split from the drop-down list or use the data picker button and select an object from the window.

4. Define the Output Wireframe, cutting strings projection, Block ID, optional additional cutting planes orientation and reference point parameters.

5. Click OK.

This is a complex geometric task and by necessity makes some assumptions of the input data. The input wireframe must have been verified without any shared edges, intersections or open edges (if a closed volume). If a key field was necessary for a successful verification, then it should also be used as the key field for this function. Open strings should pass completely through the wireframes they are segmenting i.e. extend beyond the wireframe's limits.  A partial cut will not create separate segments. Closed strings can be within the wireframe limit, as they clearly define a separate region. The Block ID classification assumes that each wireframe segment is clearly on one side or the other of each string. Open strings which do not pass across the entire wireframe extents may lead to ambiguous classification and possibly erroneous results. Planes should preferably be perpendicular to the cutting strings. Planes which are parallel to the cutting strings will prevent the creation of the additional closing edges on Closed Volume wireframes and may lead to erroneous results. Strings or cutting planes which exactly align with wireframe triangle surfaces may lead to problems in the internal Boolean functions and erroneous results. If this is suspected, then moving the string or wireframe a tiny amount away from the triangle surface will usually create a successful result.

 

Example

Example 1: Dividing a closed volume with open strings

In this example, the _vb_mintr wireframe from the tutorial data set is divided by a series of strings describing a rough 2D grid. Since the wireframe object contains 2 adjacent volumes identified by the ZONE field, that is used as a Key Field. No additional cutting planes were used.

A Plan view of the input wireframe object and cutting strings:

 

A Plan view of the output wireframe object, coloured by BLOCKID:

 

A 3D view of output wireframe object, coloured by BLOCKID:

 

A close up view of one the individual wireframe blocks, showing the new sides (in grey) which have been added to make it a closed volume:

 

Example 2: Dividing a closed volume with open strings

In this example, the _vb_stoptr wireframe from the tutorial data set is divided by a series of closed perimeters outlining some notional key areas.

A Plan view of the input DTM wireframe object showing the cutting strings (perimeters):

 

A Plan view of the output wireframe object, coloured by BLOCKID:

 

A side 3D view of the output wireframe object, showing that, unlike with the closed wireframe, no additional sides have been created:

 

McAfee Firewall Implications The library used for some of the new wireframe functions uses the localhost address 127.0.0.1 for internal communications. This is not an external internet address, and will be automatically redirected back to the computer by its network card, however, some firewall configurations, such as the setup adopted by McAfee antivirus applications, detect this as an attempt to access the internet and may erroneously report a warning. If this happens, please allow access, and the function should continue as normal. The functions in question will not be accessing the internet, and will perform without problem if an internet connection is not present. In essence, you are permitting your antivirus software to perform a local operation.

 

	Related Topics
	Boolean operations