+ Reply to Thread
Page 1 of 2 1 2 LastLast
Results 1 to 10 of 16
  1. #1
    Junior Member
    Discipline
    Architectural
    Using
    AutoCAD 2014
    Join Date
    Jun 2017
    Posts
    10

    Default How to draw the boundary(or maximum outline) of a point set?

    Registered forum members do not see this ad.

    How to draw the boundary(or maximum outline) of a point set? Require all points to be on the outline or inside the outline

    By looking up academic materials, it seems to be a concave hull algorithm。

    concave hull
    01.jpg

  2. #2
    Senior Member ziele_o2k's Avatar
    Discipline
    Construction
    Using
    AutoCAD 2018
    Join Date
    Jun 2014
    Location
    Poland
    Posts
    137

  3. #3
    Super Member marko_ribar's Avatar
    Computer Details
    marko_ribar's Computer Details
    Operating System:
    Windows 7 Ultimate X64
    Computer:
    Intel quad core CPU 4x2.66GHz, 8GB RAM
    Motherboard:
    INTEL compatibile
    CPU:
    quad core 4x2.66GHz
    RAM:
    8GB
    Graphics:
    NVIDIA GeForce 6600 GT
    Primary Storage:
    250 GB
    Secondary Storage:
    500 GB
    Monitor:
    Samsung 17''
    Discipline
    Architectural
    marko_ribar's Discipline Details
    Occupation
    Architecture, project designer, project visualisation
    Discipline
    Architectural
    Details
    space design - modeling and animations
    Using
    AutoCAD 2014
    Join Date
    Feb 2010
    Location
    Belgrade, Serbia, Europe
    Posts
    1,290

    Default

    Are your points like in the picture - spaced like grid and should boundary always be orthogonal like in your picture?

    Marko Ribar, d.i.a. (graduated engineer of architecture)
    M.R. on YouTube

  4. #4
    Quantum Mechanic BIGAL's Avatar
    Using
    Civil 3D 2016
    Join Date
    Dec 2005
    Location
    GEELONG AUSTRALIA
    Posts
    10,702

    Default

    Architecture has a command called "shrinkwrap" may not be in 2014 try it. I have used in CIV3d but for 3dfaces and works great. Will test points.

    Ok did not work as its points and uses lines.

    Take every point and draw a line to every other point, erase any line over root 2 1.1414 times the grid spacing, use lineworksshrinwrap, this will make a outer boundary pline put on another layer delete all the point joins lines. Note will only work with a grid.
    A man who never made mistakes never made anything

  5. #5
    Luminous Being Tharwat's Avatar
    Discipline
    Mechanical
    Tharwat's Discipline Details
    Occupation
    MEP AutoCAD Draughtsman
    Discipline
    Mechanical
    Details
    HVAC, Drainage, Water Supply, Fire Fighting and a little about Electricity.
    Using
    AutoCAD 2017
    Join Date
    Oct 2009
    Location
    Great Syria , Living in Abu Dhabi
    Posts
    6,246

    Default

    Hi,

    If these points are a hatch pattern then hatchedit should get the job done with the option recreate boundary.

  6. #6
    Junior Member
    Discipline
    Architectural
    Using
    AutoCAD 2014
    Join Date
    Jun 2017
    Posts
    10

    Default

    Thank you for your reply.
    This is just a special case. Not all point spacing is equal. I want to find a general method.

  7. #7
    Junior Member
    Discipline
    Architectural
    Using
    AutoCAD 2014
    Join Date
    Jun 2017
    Posts
    10

    Default

    Quote Originally Posted by BIGAL View Post
    Architecture has a command called "shrinkwrap" may not be in 2014 try it. I have used in CIV3d but for 3dfaces and works great. Will test points.

    Ok did not work as its points and uses lines.

    Take every point and draw a line to every other point, erase any line over root 2 1.1414 times the grid spacing, use lineworksshrinwrap, this will make a outer boundary pline put on another layer delete all the point joins lines. Note will only work with a grid.
    Thank you for your reply.Not all point spacing is equal.This is just a special case

  8. #8
    Quantum Mechanic BIGAL's Avatar
    Using
    Civil 3D 2016
    Join Date
    Dec 2005
    Location
    GEELONG AUSTRALIA
    Posts
    10,702

    Default

    If you search here there is some Triangulation software it will make a mesh of random points, then you can use shrinkwrap,, problem is the mesh has to be edited removing non essential 3dfaces, this is something done in the civil surface world all the time.


    You could still take the approach I suggested to make some form of shape removing lines, the obvious is the remove long lines 1st for us this = about 90% done, then erase the lines in the corners.


    lee's Convex hull may be a starting point, but even looking now misses some edges compared to what I wanted as a final product. Random points is a real problem.
    A man who never made mistakes never made anything

  9. #9
    Super Member marko_ribar's Avatar
    Computer Details
    marko_ribar's Computer Details
    Operating System:
    Windows 7 Ultimate X64
    Computer:
    Intel quad core CPU 4x2.66GHz, 8GB RAM
    Motherboard:
    INTEL compatibile
    CPU:
    quad core 4x2.66GHz
    RAM:
    8GB
    Graphics:
    NVIDIA GeForce 6600 GT
    Primary Storage:
    250 GB
    Secondary Storage:
    500 GB
    Monitor:
    Samsung 17''
    Discipline
    Architectural
    marko_ribar's Discipline Details
    Occupation
    Architecture, project designer, project visualisation
    Discipline
    Architectural
    Details
    space design - modeling and animations
    Using
    AutoCAD 2014
    Join Date
    Feb 2010
    Location
    Belgrade, Serbia, Europe
    Posts
    1,290

    Default

    As far as I can tell, correctly implemented triangulation to random set of points should return convex hull boundary - not concave...

    Marko Ribar, d.i.a. (graduated engineer of architecture)
    M.R. on YouTube

  10. #10
    Quantum Mechanic BIGAL's Avatar
    Using
    Civil 3D 2016
    Join Date
    Dec 2005
    Location
    GEELONG AUSTRALIA
    Posts
    10,702

    Default

    Registered forum members do not see this ad.

    You are correct Marko the issue is to do with what we call long triangles have a look at this image, left is as built right is after edits and has the correct boundary.

    Looking now 3 mistakes ? Need to fix and redo, these were little tiny slivers so the correct answer is both concave and convex, then LINEWORKSHRINKWRAP. We use delete long triangles via a length factor reducing till we start erasing ones we need then it becomes maual edits. I have been told we may have a 3rd party solution from our surveyors.

    left after create triangles, middle is correct answer, right is convexhull.lsp
    Attached Images
    Last edited by BIGAL; 7th Jul 2018 at 12:22 am.
    A man who never made mistakes never made anything

Similar Threads

  1. How to add a single boundary outline around multiple hatches.
    By Holybod in forum AutoLISP, Visual LISP & DCL
    Replies: 20
    Last Post: 19th Mar 2015, 03:40 pm
  2. Draw a maximum number of circles inside in polygon
    By teknomatika in forum AutoLISP, Visual LISP & DCL
    Replies: 4
    Last Post: 4th Sep 2014, 03:24 pm
  3. Maximum distance on a curve from point list
    By aaryan in forum AutoLISP, Visual LISP & DCL
    Replies: 6
    Last Post: 28th Jan 2013, 03:00 pm
  4. Replies: 1
    Last Post: 29th Aug 2011, 10:00 pm
  5. Maximum Point number
    By MARKY in forum AutoCAD General
    Replies: 0
    Last Post: 21st Apr 2010, 07:39 pm

Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts