![]() Since geometry is best comprehended visually, Manifold uses a visual, drawing user interface to present geometry. It is impractical in a text, tabular presentation to convey a visual impression of geometry so instead when the Geom (I) column is turned on a table will report some summary information about the metric for that object: the type of geometry data, the type of object (area, line or point), the number of branches and the number of coordinates. The Geom (I) column reveals the geometry column of a table, wherein the metric of each object is stored using Manifold's own Geom data type, a form of binary data that encodes an object's metric. We can see the geometry data within every drawing's table by turning on the Geom (I) implicit field. Since geometry is best understood using a visual interface, by default the geometry in a table is shown using a drawing. It is just a question of how different types of information are best displayed and used. ![]() The truth of the matter is that inside Manifold all information for drawings, both geometry and attributes, is stored within tables. But the truth is deeper, more general and more powerful than that. The way Manifold is taught to beginners together with the routine use of drawings and the tables of drawings conveys the idea that the geometry of objects is stored within the drawing and the data attributes are stored in the drawing's table, as if they were two different storage locations. Data attributes in tables are normally the sort of information that is easiest to comprehend and edit within a classic, text, row and column tabular user interface. When we pop open the drawing's table in a table window we see any data attributes in a classic row and column tabular presentation. When we pop open the drawing component in a drawing window it paints the objects in the drawing for us.īecause GIS as done interactively is primarily a visual activity, drawings and other visual displays take the lead role in Manifold's user interface. When working with drawings in Manifold we quickly become used to the idea that there are two parts to a drawing: the drawing component itself and the drawing's table. The metric of a specific object is the geometric data that defines that object. The information that defines the locations of points and the locations and shapes of lines and areas is called the geometry of the drawing. If there are any data attributes attached to the drawing's objects, those attributes will appear as columns in the table. A drawing's table has a record, a horizontal row, for each object. Let's begin with a refresher on nomenclature: the objects in a drawing are the areas, lines and points that make up that drawing. For the more simple case of geocoded tables, see the Linked Drawings from Geocoded Tables topic. That is a more advanced usage than the relatively simple case of geocoded tables, where some columns give lists of X/Y or latitude and longitude locations. This topic discusses the storage of geometry within tables, whereby binary data representing the shapes and locations of objects is stored within the table.
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