NEW ILWIS 3.7 VECTOR FUNCTIONS

New ILWIS 3.7 vector functions

PointMapUnion
PointMapIntersect
PointMapSymetricDifference
PointMapDifference
PointMapRelate
SegmentMapVoronoi
SegmentMapTin ( not sure yet if this one will make it to the final)
SegmentMapUnion
SegmentMapIntersect
SegmentMapSymetricDifference
SegmenMapDifference
SegmentMapRelate
PolygonMapBuffer
PolygonMapConvexHull
PolygonMapUnion
PolygonMapIntersect
PolygonMapSymetricDifference
PolygonMapDifference
PolygonMapRelate

New ILWIS 3.7 Polygon Applications

PolygonMapBuffer

The buffer of a Point/Segment/Polygon at a distance r is the Polygon or MultiPolygon which contains all points within a distance d of the feature.

 

Syntax
PolygonMapBuffer(InputMap, BufferDistance,EndCapStyle);

The operation has three parameters:

PolygonMapConvexHull

The convex hull of a Point/Segment/Polygon is the smallest convex Polygon that contains all the points in the Point/Segment/Polygon (collection).

Syntax
PolygonMapConvexHull(InputMap, isCombined)

PolygonMapDifference

Calculates the difference between polygons in the two inputmaps. From Each polygon in the first input map the covering polygon(s) from the second input map, if any, is substracted.

(grey and orange lines are the boundaries of the original 2 polygons)

Syntax
PolygonMapDifference(Inputmap1,  Inputmap2)

PolygonMapSymetricDifference

Calculates the symmetric difference between polygons in the two inputmaps. From Each polygon in the first input map the symmetric difference with any of the polygons from the secondmap is calculated

Syntax
PolygonMapSymetricDifference(Inputmap1,  Inputmap2) 

PolygonMapIntersect

Calculate the intersection of  a polygon of the input map with polygons of the output map. The map will be associated with an attribute table that contains the values of the original maps in a certain polygon.


(grey and orange lines are the boundaries of the original 2 polygons)

Syntax
PolygonMapIntersect((Inputmap1,  Inputmap2)

PolygonMapRelate

For each polygon in the first inputmap a Boolean test is done to each feature in the second output map to see if it holds true. If so, the polygon is included in the output map.

The following relations are implemented

Example for “contains”; only polygons that contain the pointmap (yellow dots) are shown.

Syntax
PolygonMapRelate(inputmap1, Inputmap2, relation, negation)

PolygonMapUnion

Merges polygons of the first input map with polygons of the  second input map

New Segmentmap Applications

The set operations for segments are identical for segmentmaps: SegmentMapIntersect, SegmentMapDifference, SegmentMapSymetricDifference, SegmentMapUnion, SegmentMapRelate. The only difference is that the set operations for segmentmaps can use a polygonmap (if it is not a segmentmap) as second inputmap. In such a case, the operation works on the boundaries of the polygonmap.

SegmentMapVoronoi

From a pointmap, it creates the segmentmap that forms the Voronoi map in which all points on the segments have equal distance to the closest points. Note that the “areas” are not closed, because the boundary segment at the edge of the map would, in theory, go on forever.



Syntax
PolygonMapRelate(Input Pointmap, minimal distance)

 

SegmentMapTIN

Creates an irregular triangulated network from a input pointmap. This is a ‘bare bones’ implementation of a TIN and only deals with the creation of the segment map. Optionally it can choose to use conves hulls for elements at the edge of the TIN to create a better area filling.



Syntax
SegmentMapTIN(Input pointmap, use Convex hull)

New Pointmap Applications

The set operations for pointmaps are identical for segmentmaps: PointMapIntersect, PointMapDifference, PointMapMapSymetricDifference, PointMapMapUnion, PointMapMapRelate. The only difference is pointmap intersect accepts Pointmaps, Segmentmaps or Polygonmaps as input. It will use the intersection of segments and boundaries to determine the intersection points.

PointMapPointInSegment

A convenience application that determines a suitable point in a segment to determine its “middle”. This can be a real centroid, an existing vertex that is the best estimate or a point on of the edges that is closest to the centroid.

The three options in one map. Triangle=Centroid, Circle=Vertex, Diamond=MiddlePoint.

Syntax
PointMapPointInSegment(input segment map, option)