dxf-polygon-cleaner

DXF Polygon Cleaner

Takes the result table of dxf-polygon-importer and runs cleaning and validation functions on a given file, project and version combination.

The initial version was developed to solve following geometry problems:

Key for yellow numbered test problem sets:

• Overlapping polygons and duplicate labels
• Multiple labels
• Split label ('0', '002')
• C shaped polygon
• C shaped polygon with empty core
• Self-intersecting geometry with duplicate label
• Doughnut geometry
• Doughnut geometry with label only in core (should be in ring)
• '009A' appears as polygon, but is only enclosed by line on the left
• 2 Overlapping polygons
• 3 Overlapping polygons (one that contains both)
• Doughnut with label in core and ring
• Orphaned label
• Non-compact shape type without label

Installation and requirements

npm install dxf-polygon-cleaner

The module requires a PostGIS enabled PostgreSQL database (version 9.3 or higher) and expects a database structure created by the dxf-polygon-importer.

Following environment variables need to be set:

DXF_TOOLS_DB_HOST              ...  PostgreSQL server host
DXF_TOOLS_DB_PORT              ...  PostgreSQL server port
DXF_TOOLS_DB_USER              ...  Database user name
DXF_TOOLS_DB_PASSWORD          ...  Database user password
DXF_TOOLS_DB_NAME              ...  Database name

Sensible database connection defaults are applied for typical 'localhost' environments, a database-name is required however.

The module will create a table approved_dxf_features, for permantly storing a single version of approved features, and 2 temporary views, for accessing the latest versions per feature type, project and filename.

Usage

var Cleaner = require('dxf-polygon-cleaner');

// Cleaner(filename, project, version);
var cleaner = Cleaner('mydrawing.dxf', 'myproject', 1);

cleaner.setup().then(function () {

  // data cleaning and/or validation methods

}).then(function () {
  return cleaner.teardown();
});

Run tests

Requires a test database.

$ npm test

API

initialize Cleaner(filename, project, version)

The class takes 3 arguments to identify the feature collection that should be processed: the filename of the imported dxf file, the project identifier and the imported version.

setup Cleaner.setup()

Creates temporary views to make succeeding database queries and operations a little easier.

teardown Cleaner.teardown()

Removes temporary views and ends the database connection pool.

fixDoughnuts Cleaner.fixDoughnuts()

Creates doughnut geometries and removes overlaps of polygons and their completely contained polygons.

deleteEmptyPolygons Cleaner.deleteEmptyPolygons()

Deletes all polygons with an area smaller than 1 [square-unit].

labelPolygons Cleaner.labelPolygons()

Assigns labels as names to enclosing polygons.

fixDoughnutLabels Cleaner.fixDoughnutLabels()

Moves labels from cores to non-labeled rings of doughnut geometries.

flagPolygons Cleaner.flagPolygons()

Adds following validation flags to all polygons:

hasLabel, hasManyLabels, hasSharedLabels
compactness, area
isOverlapping, overlappingPolygons
isValid, validReason

The compactness indicator measures shape form and is calculated by the following formula:

Example values:

• cirlce: 1
• square: ~0.8
• long shaped corridor: ~0.15

flagLabels Cleaner.flagLabels()

Adds following validation flags to all label points:

isInPolygon, isInManyPolygons

approvePolygons Cleaner.approvePolygons(options)

Inserts a copy of the currently processed features into approved_dxf_features, and deletes any prior existing versions in that table.

{
  endPool:   true|false  end database pool when done
}

getInvalidGeometryDetails Cleaner.getInvalidGeometryDetails()

Return a GeoJSON object with point geometries and meta information of possibly problematic geometries, like self-intersections.

getGeoJson Cleaner.getGeoJson(options)

Return a GeoJSON Feature collection of the currently processed features. It takes and options object with following properties:

{
  approved:  true|false  return only approved features
  endPool:   true|false  end database pool when done
}

setVersion Cleaner.setVersion()

Finds the most recent version of a project and filename combination and sets the Cleaner._version property accordingly. Useful when defaulting to the last version.

fullService Cleaner.fullService()

Alias for running common tasks:

• fixDoughnuts
• deleteEmptyPolygons
• labelPolygons
• fixDoughnutLabels
• flagPolygons
• flagLabels
• getGeoJson

Returns GeoJSON.