Drawings - Object Coordinates

The Object Coordinates dialog appears as the Coordinates choice in the context menu when we right click on an object in a drawing. The dialog allows direct editing of the coordinates that comprise the object.

 

Please read the Coordinates topic if you have not already done so. This topic describes how objects are defined by the coordinates that are used to draw them in a "connect the dots" fashion.

 

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The Object Coordinates dialog displays the list of coordinates that define the object that was right clicked. Editing this list will change the shape and/or position of the object. A + sign in the first column indicates the beginning of each branch of an object.

 

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New - Create a new coordinate in the list that is a duplicate of the currently selected coordinate (lines and areas only).

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New Branch - Insert a new branch (lines and areas only). A branch is a separator between coordinate lists used to define complex objects such as areas that contain holes.

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Break Branch - Break branch at highlighted coordinate (lines only, disabled unless there are at least two points before and after highlighted coordinate).

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Delete - Removes highlighted coordinate (lines and areas only, disabled for area branches containing three points and line branches containing two points).

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Delete Branch - Delete highlighted branch (lines and areas only, disabled when there is only one branch left).

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Move to Top - Move highlighted coordinate to start of branch (lines and areas only, disabled when coordinate is already at start of branch).

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Move Up - Move highlighted coordinate one step up (lines and areas only, disabled when coordinate is already at start of branch).

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Move Down - Move highlighted coordinate one step down (lines and areas only, disabled when coordinate is already at end of branch).

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Move to Bottom - Move highlighted coordinate to end of branch (lines and areas only, disabled when coordinate is already at end of branch).

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Native Coordinates - Switch between coordinates within the projection coordinate system native to the drawing and Latitude and Longitude values.

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Copy - Copy the list of coordinates to the Windows Clipboard.

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Print - Print the list of coordinates through the standard print dialog.

 

This dialog is most frequently used to adjust the position of a point. Because a point is defined by only one coordinate it is easy to open this dialog and to change the X / Longitude and Y / Latitude values for the point. The dialog is less frequently used to edit areas and lines since such objects in a geographic context may be defined by thousands of coordinates.

 

One usage for areas or lines is when we wish to draw simple areas and lines in exact positions on the map. For example, suppose we want to draw a rectangular area within a Latitude / Longitude projection map that extends from latitude 38 to latitude 39 and from longitude 100 to longitude 101. An easy way of doing this is to draw a rectangle that approximately covers this region using the Insert Box tool from the Tools toolbar . We can then right click on this rectangle, choose Coordinates and then use the Object Coordinates dialog to change the four coordinates that define the rectangle into the exact values we want for the corners of the rectangle.

 

Native Coordinates

 

Native coordinates are numbers stored within the drawing that Manifold uses internally as positional coordinates. These numbers are shown in the Object Coordinates dialog. They are also used in the X (I) and Y (I) intrinsic field columns.

 

Projected coordinates are native coordinates adjusted with the local scale and local offset parameters of the coordinate system (projection) in use. In many cases, projected coordinates are the same as native coordinates (because of the local scale and offset values) but sometimes they are different.

 

Tech Tip

 

The Object Coordinates dialog may be invoked by first selecting an object for editing using smart mouse. Right clicking on one of the edit handles and then choosing Coordinates from the context menu will launch the Object Coordinates dialog with that edit handle's coordinate already highlighted and in view. See the Editing Objects topic.

 

Notes

 

Technically speaking, each line in the list defining the object is a coordinate pair. It is Manifold jargon to use the word "coordinate" to mean the pair of X / Longitude and Y / Latitude coordinates.

 

It is not possible to use this dialog to delete the last three coordinates in an area, the last two coordinates in a line or the last coordinate defining a point. To delete objects, select them and use Edit - Delete.

 

In the example noted above, of creating a rectangle covering one degree of longitude and latitude, if we intend to use this rectangle in projected maps we should Segmentize it after editing it to our satisfaction in the Object Coordinates dialog.

 

See Also

 

View - Structure

Editing Objects