What is the difference between a multipoint shapefile and a point shapefile. in the creation of a shapefile In ArcGIS it has the choice of point shapefile and multipoint shapefile. But I do not know what their difference.
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2 Answers
Shapefiles support four fundamental data types: Point, Polyline, Polygon, and Multipoint. Points are simple {X,Y} features. Polylines are ordered sets of points, and Polygons are the areas encompassed by closed simple lines. Polylines and Polygons can be multi-part to model discontinuous features, like a surface street separated by a highway, or a collection of islands.
In the shapefile model, Points can't be multi-part, but there is a distinct Multipoint type to take that role. The difference has to do with the envelope in the data record needed for Multipoint shapes and the different approach to spatial indexing of point and multipoint objects.
Multipoints are an obscure representation option for most point-ish features, but they can be used to optimize the display of large numbers of points. I had a dataset involving tens of millions of features covering the globe, and I was able to successfully draw a hundred thousand features within a single one degree square with subsecond timing by unioning the points into multipoints to reduce the number of features rendered for each tile.
Note that shapefiles don't support anything like a geometry collection, only permtting the specified shape type or a null shape (zero vertices) within one file, so if both single and multi-part point shapes are required, the single-part points will be stored as degenerate Multipoints (with a point count of one, and an "envelope" with the lower-left and upper-right corners coincident with the point itself).This is less efficient in storage (52 btyes vice 16) and the spatial index is not as efficient, either, so if you'll only have single-part points, you should use the Point datatype.
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would it be fair to say multipoint shapefile is similar to clustering? Commented Dec 11, 2017 at 14:56
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2You could implent a pointcluster with a multipoint geometry, but I wouldn't say they were equivalent. Multipoint is more of an abstract datatype.– VinceCommented Dec 11, 2017 at 15:42
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Saying that "Points can't be multi-part" is fairly absolute. Functionally, points are considered multi-part when the are grouped by their attributes. I really don't care for multi-part classes for the work I do but, I imagine that there are certain GIS sectors that find them very useful. That aside, I find ESRI's handling of lidar point clouds using multi-part geometry absolutely useless. Commented Dec 11, 2017 at 17:53
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A point can't be multi-part, by definition. After having been grouped, they are multipoints, some of which might be degenerate.– VinceCommented Dec 12, 2017 at 0:15
Take a look on, how the geometry is related to the Dbase file records. If you have a point shapefile, each point is related to one record. If you have a multipoint shapefile, a set of points is related to one record.
answered Dec 11, 2017 at 16:13
