@maplat/tin
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    0.9.1 • Public • Published

    Maplat Tin library

    JavaScript library which performs homeomorphic conversion mutually between the coordinate systems of two planes based on the control points.
    This is part of Maplat project.

    Installation

    node.js

    The easiest way to install maplat_tin is with npm.

    npm install @maplat/tin

    Browser

    Use maplat_tin.js

    <script type="text/javascript" src="maplat_tin.js"></script>

    How to use (node.js case)

    var Tin = require('maplat_tin');
    
    var tin = new Tin({
        wh: [500, 500],
        yaxisMode: Tin.YAXIS_FOLLOW
    });
    
    tin.setPoints([
      [[100,100], [200, 200]],
      [[200,200], [400, 400]],
      [[150,150], [320, 350]],
      [[200,100], [420, 220]]
    ]);
    tin.updateTinAsync().then(function() {
      if (tin.strict_status == Tin.STATUS_STRICT) {
        console.log('Topology OK: In this case, roundtrip transform is guaranteed');
      } else if (tin.strict_status == Tin.STATUS_LOOSE) {
        console.log('Topology error: In this case, roundtrip transform is not guaranteed');
      } else {
        console.log('Something wrong');
      }
    
      //Forward transform
      var ord = tin.transform([160, 160], false);
      console.log(ord);
      //ord => [336.0769755832048, 360.048109739503]
    
      //Backward transform
      var rev = tin.transform(ord, true);
      console.log(rev);
      //rev => [160, 160]
    
      //Solving triangulated irregular network from many points by scrach takes too many time.
      //So, there are object-serialization method to store solved instance.
    
      var compiled = tin.getCompiled();
    
      var tin2 = new Tin();
      tin2.setCompiled(compiled);
      // Compiled triangulated irregular network was set. no "updateTinAsync" call is need.
    
      var ord2 = tin.transform([160, 160], false);
      console.log(ord2);
      var rev2 = tin.transform(ord2, true);
      console.log(rev2);
      //Same results with ord, rev
    }).catch(function(e) {
      if (e == 'TOO LINEAR1' || e == 'TOO LINEAR2') {
        console.log('Given GCP points are too linear, fail to create triangulated irregular network.');
      } else {
        console.log('Something wrong');
      }
    });

    Options

    wh (method: setWh)

    Set width and height of the first coordinate system.
    NOTE: If setWh was called, TIN network is reset. So need to call updateTinAsync() again.

    yaxisMode

    Set Tin.YAXIS_FOLLOW if the y coordinate of the first coordinate system is the same as the direction of the y axis of the second coordinate system, and set Tin.YAXIS_INVERT if it is in the opposite direction.
    Default value is Tin.YAXIS_INVERT.

    points (method: setPoints)

    A set of corresponding points in the first coordinate system and the second coordinate system is specified as an array. Minimum 3 points required. Also, if the alignment of points is too linear, TIN can not be calculated at updateTinAsync and an error occurs.
    NOTE: If setPoints was called, TIN network is reset. So need to call updateTinAsync() again.

    Methods

    updateTinAsync()

    Return value is Promise. Calcurate TIN asynchronously. Before calling transform, this method needs to be completed.

    transform(xy, inverse)

    Convert the coordinates. If the value of inverse is false, the direction of conversion is from the first coordinate system to the second one, if it is true, the direction of conversion is reverse direction.

    Properties

    strict_status

    Confirm after completion of updateTinAsync(). When the value is Tin.STATUS_STRICT, bijection conversion is guaranteed. In the case of Tin.STATUS_LOOSE it is not guaranteed.

    Keywords

    Install

    npm i @maplat/tin

    DownloadsWeekly Downloads

    8

    Version

    0.9.1

    License

    Maplat Limited License 1.1

    Unpacked Size

    1.4 MB

    Total Files

    18

    Last publish

    Collaborators

    • kochizufan