Objects Overview

The most commonly used geometries in map drawing are points, lines, polygons, and text. The Edit Data tab provides functions for creating various types of geometries on the map, including point objects, line objects, polygon objects, and text drawing.

Drawing of various geometries is performed while the layer is editable. Multiple layers can be set editable simultaneously, but when creating points, lines, polygons, or text, only the currently selected layer is used for geometric objects. Therefore, to create a new object for a layer, you must first click the corresponding layer in the Layer Manager to set that layer as the current layer.

The following introduces some concepts involved in objects:

Object Overview

Object: a geometry, an abstract representation of discrete spatial entities in GIS. An object has its own properties and behaviors. In SuperMap, some objects can be created directly, while others need to be generated through conversion.

  • Single Object: refers to one object. A simple object, a complex object, a compound, and a part are all single objects.
  • Part: refers to the constituent units of simple objects and complex objects. A simple object consists of one part, which is itself; a complex object consists of two or more parts.
  • Simple Object: an object that has only one part (i.e., itself).
  • Complex Object: an object that has two or more parts, and these parts are of the same type.
  • Compound Object: specifically refers to objects generated by combination operations in a CAD layer. Compound objects do not have the concept of parts.
  • Parametric Objects: geometries drawn using key parameters, which are continuous. Ordinary geometries are drawn using the key points or the coordinates of point strings that compose the object. For example, a parametric circle is precisely drawn using the center and radius as two parameters; while an ordinary circle discretizes the arc into points and then connects these points with lines to form a closed circle.

Angle Description in Objects

  • Angle Direction: The angle direction involved in the application is counterclockwise.
  • Start Angle: The start angle in drawing objects refers to the angle between the due north direction (as the starting side) and another side.

Parametric Drawing Description

When drawing the line, it will split the original and new object at the intersection, and create multiple line objects, making the drawing process more convenient. You can enable the parametric drawing function by clicking the Parametric Drawing button in the Object Drawing group of the Edit Data tab, or by pressing Shift+P.

  • Enter Coordinate Values: Draw points, lines, polylines, curves, circles, polygons, etc., using coordinate point parameters, including the start point, midpoint, turning point, and end point of the object.
  • Enter Length Values: Draw lines, polylines, polygons, sectors, circles, arcs, etc., by entering length parameters of the object, including limit length, side length, radius, diameter, etc.
  • Enter Angle Values: Draw objects by entering angle values to determine the drawing direction and start angle.

Parametric Objects

Feature Description of the Shift Key

Using the Shift key while drawing some objects can make the drawing process more convenient.

  • Drawing a Line: When drawing a line by entering length and angle parameters, holding down the Shift key allows you to draw only horizontal, vertical, or 45° lines.
  • Drawing a Rectangle (Rounded Rectangle): When drawing a rectangle by entering width and height parameters, holding down the Shift key will result in a square with equal width and height.
  • Drawing an Ellipse: When drawing an inscribed ellipse, holding down the Shift key will result in a perfect circle with equal width and height.

Feature Description of the A Key

When drawing objects on the map, pressing the letter A on the keyboard can switch the mouse in the current map to drawing pan mode, and the mouse state in the current window will be .

After switching the mouse to drawing pan mode during object drawing, you can switch the mouse state back to drawing mode and continue drawing objects using one of the following three methods:

  • Press the A key again to switch;
  • Right-click the mouse to switch;
  • Press the Esc key on the keyboard to switch.
Tip:
  • If you are entering coordinates, lengths, or angles for drawing objects when pressing the A key, the mouse cannot be switched to drawing pan mode.
  • When opening an empty map (geographic coordinate system), the default range of the window is the drawable bounds, which can effectively avoid the prompt of exceeding the range when drawing objects in the default window range.

Feature Description of the Q Key

When drawing line or polygon objects on the map, pressing the Q key on the keyboard enables the snapping function. When the mouse stops and moves to the boundary of an existing object, it will automatically snap to the boundary, avoiding topology errors.

  • Press the Q key once to enable the snapping function;
  • Press the Q key again to disable the snapping function;