Easily Delete Linear Elements Partially Overlapping Other Linear Elements

By Eiren Smith, Axiom’s Vice President for Technology - www.axiomint.com
Accidental, duplicate elements are a fact of life for nearly all MicroStation sites. They cause plotting problems, selection trouble (elements that take forever to select with the Area Selection tool, because MicroStation may be selecting dozens or even hundreds of duplicates hidden under those you intended to select), deletion difficulties (“I just deleted that element - and it came right back!”), unexpected results with third-party automation software that has no idea that the area you asked it to process includes numerous duplicate elements that you didn’t know about and did not want processed, unnecessarily large files padded with duplicate elements and a host of other site-specific problems.

Duplicate elements come from many sources and come in varied forms. That is, there are many ways elements can be considered “duplicates”. Obviously, there are the simple cases of “perfect duplicates.” From a programming point of view, those are the easiest to locate and handle. However, there are many other ways elements can be considered duplicates from a production standpoint.

In this technical bulletin, I address one of the more annoying forms of duplicate or near-duplicate elements: linear elements fully overlapped by other, longer linear elements. The overlapped elements could be significantly smaller than their overlapping counterparts, making them hard, sometimes practically impossible, to locate without the assistance of advanced software. The problem is solved using the latest addition to Axiom’s Duplicate Element Remover. The following steps demonstrate exactly how to get rid of this type of duplicate element.

1. Select Duplicate Element Remover from the Axiom pull-down menu [located on the MicroStation menu bar].
   
   
   
   
2. Duplicate Element Remover’s main dialog appears. Your active design file will be selected by default. To process a different file (or multiple files), click the <Select…> button. For the purposes of this article, we will work with a test design file, overlap.dgn.
   
   
   
   
3. To begin, we will load Duplicate Element Remover’s default settings. From the main dialog box, choose “Settings | Reset to factory defaults…” and answer <Yes> to the confirmation box that appears.
4. Once the factory settings are restored, go to “Settings Change Settings…”
   
   
   
   
5. In the Category list, choose “Tolerances”.
6. Turn on the checkbox next to “Remove linear elements overlapped by longer elements?” A few other options will automatically be activated. This is okay.
   
   
   
   
7. Now, keep in mind that it is possible for lines which look like perfect duplicates to be less-than-perfect duplicates if they each contain different non-graphic information - information you can’t necessarily see. Attribute linkage information is a good example of this. For the purposes of this bulletin, we are not concerned with attribute linkages. In order for Duplicate Element Remover to treat near-duplicate elements with different attribute linkages as perfect duplicates, simply set the settings under the “Attribute linkages” Category as in the image below or make adjustments according to your own preference.
   
   
   
   
8. Then, on the same dialog box, choose <OK> to go back to the main dialog box.
9. Back in the main dialog box, check the box next to “Generate report only”. In “Generate report only” mode, Duplicate Element Remover will not delete any elements - it will simply create reports of what duplicate elements it found.
   
   
   
   
10. Next, uncheck the box next to “Interactive mode”.
    Note: In this article, we run Duplicate Element Remover in non-interactive mode. In non-interactive mode, Duplicate Element Remover will process all your elements automatically without requiring you to make a decision for each one. Using Duplicate Element Remover in non-interactive mode is a great way to quickly see how many duplicate elements are in your files.
    
    
    
    On the other hand, interactive mode gives you the finest level of control. In this mode, Duplicate Element Remover will let you “visit” each duplicate element it finds. While visiting each duplicate element, you can choose to delete it or not. This is a great way to get a hands-on feel for what types of duplicate elements exist in your files. In everyday operation, you can choose whether you want to run in interactive or non-interactive mode.
11. Press <Start> to begin processing the design file.
12. After processing the design file, Duplicate Element Remover creates two report files:
    • A text report file (*.trf) which is a simple text file listing all the duplicate elements found; and
    • A design report file (*.drf), my personal favorite. Design report files graphically show you exactly what duplicate elements were found, presented in their relative location to the other elements in your file. You can think of design report files as “duplicate element X-ray glasses.” With them, you can essentially look right into a file and see only its duplicate elements.
13. To see what duplicate elements Duplicate Element Remover found, press the <View Design Report File> button. The green elements are the duplicates; the white (color 0) elements are all the non-duplicate elements in the file, included (and turned white) to distinguish them from the duplicate elements.
    
    
    
    
14. If you agree that the green elements shown in the design report file are valid duplicates, process the file once again with the “Generate report only“ box unchecked, and, at your discretion, process the file in either interactive or non-interactive mode. After this step, you will find that your duplicate elements are gone. That’s all it takes!

Click here to find out more about Duplicate Element Remover.

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