Intersection between lines do not meet exactly

David Winthrop
David Winthrop
in BricsCAD BIM
I recently noticed that if I use either intersection or apparent intersection while drawing a new line or copying a line onto an existing object that if I zoom in the new line will either be just short or just beyond where I was trying to copy it to.  All elevations for the Z axis are at 0.  Any ideas how to fix this so my lines meet up exactly? 

Comments

  • Scott McKenzie
    Scott McKenzie
    I think this might be the the issue that you are running into...

  • Joe Dunfee
    Joe Dunfee
     I will throw out another possibility.  Depending on how much you zoomed in, and how much you were zoomed out before, you might find that this is just a display artifact, and not an actual distance for the end points.  A similar thing may happen if you draw a small circle, then zoom out a zillion fold, and then zoom back to that circle.  You may find that your circle now looks like a square. 

    This is because the CAD program maintains an internal database that is only used for display to speed up the process of redrawing the screen.  It recalculates this internal display database any time it does a regeneration. (Regen is the command that will force this).  If you zoom out a zillion times, it may automatically regenerate, and then when you zoom back in, that circle is now drawn much coarser.

    Sometimes this happens by accident, if for example you intended to copy something 1.0625" away, and omit the decimal place, and so it is copied 10,625" away. The next time you zoom/extents, you will find your drawing way too small (or even invisible), but if you undo that, you can get rid of the high zoom and the stray object.  But, it may be that the regeneration of the view is not redone.

    A simple Regen command when you are zoomed back in may fix the problem.

    -Joe
  • John Gaunt
    John Gaunt
    I don't know if it's the same issue, but occasionally two lines won't Join (which should) or Bcad can't find an obvious intersection or chamfer won't work, because the Z of one or more lines has apparently become slightly not 0. For want of a better description.
    If I select every line in the drawing and Flatten them, everything works again.
    This has been happening for a number of versions now, I had kind of gotten used to it.
  • Roy Klein Gebbinck
    Roy Klein Gebbinck
    @ David: Can you post an example dwg?
  • David Winthrop
    David Winthrop
    I tried flattening the drawing and I am still getting the same result, when using entity snaps I'll copy the Endpoint of one line and bring it onto Nearest of the next line I want these lines to connect to.  When I zoom in very close these lines never meet up perfectly.  The only way I can do this is to trim or extend every line manually otherwise they are off just slightly.  Drawings and pics are attached.
    imagenot lined up.JPG

    Lines gapped and overlapped.dwg

    imagegapped.JPG
  • Joe Dunfee
    Joe Dunfee
     I don't know which parts of the drawing show the problem intersections.  The one I looked at was fine.  However, i did notice something that may be part of the problem.

    If you Zoom/Extents, you will see that there are some objects that are way out in left field... well actually much further than that if you consider the size of a baseball field.  When I list the overall distance it in inches, I get 18,047,012  So, I think you are dealing with such an EXTREMELY large drawing, so that BricsCAD just does not have the decimal places to do the kind of precision you are seeking.  if you really want do do a drawing that is 18 million inches across, you can't also expect the precision to draw details that are a tiny fraction of an inch.

    -joe
  • Louis_Verdonck
    Louis_Verdonck

    A similar thing may happen if you draw a small circle, then zoom out a zillion fold, and then zoom back to that circle.  You may find that your circle now looks like a square.

    The WHIPARC system variable controls whether circles and arcs display as true circles or as a series of vectors. If WHIPARC = ON, arcs and circles always display correctly. If WHIPARC = OFF a REGEN might be necessary to correctly display arcs and circles.
  • Roy Klein Gebbinck
    Roy Klein Gebbinck
    @ David:
    There is no need for a 'Flatten' macro. BricsCAD has a _FLATTEN command.
    Your example is not very clear. Where should I look?

    What value do you use for the LWDISPSCALE variable? Using the default value of 0.55 is problematic since you have parallel lines that are very close together. With the mentioned value, lines on the 'Walls - exterior' layer can completely obscure lines on the 'Lines - Medium' layer making picking correct osnap points much harder.
  • Roy Klein Gebbinck
    Roy Klein Gebbinck
    ... OK I think I have to zoom in on the red line...

    The problem is that almost all line are not exactly orthogonal. Change the AUPREC variable to check this yourself.
    To salvage some of your work you can try to create a DXF from your drawing using DXFOUT with a reduced accuracy.
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