# Displaying Distance, Length, Perimeter, and Area Calculations - MapInfo_Pro - 2023

## MapInfo Pro Help

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2023
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MapInfo Pro
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MapInfo Pro Help
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1985
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2023-09-12
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2023-09-12T16:39:16.995549

Double-clicking on an object type, such as lines, rectangles, rounded rectangles, region, polyline, and ellipses, displays information about the object. This information includes measurement; the type of calculation method used to calculate measurement displays in parenthesis after the measurement.

The Convert to Polylines command simplifies the task of creating buffer regions that have a hole in the middle of them. Suppose you want to create a buffer representing the area within one mile of a county boundary. You may want the buffer to have a hole in the middle of it and extending exactly one mile to either side of the county line.

You could create a buffer simply by selecting the county region and choosing to buffer it: on the SPATIAL tab, in the Edit group, click Buffer Objects from the list. However, the resultant buffer would not have a hole in the middle of it. Instead, it would contain all of the county, plus an area of one mile outside the county.

If you convert the county region into a polyline before you choose to buffer it, then the resultant buffer region includes a hole in the middle of it.

Convert to Polylines lets you perform node-editing operations (such as adding and moving nodes) on objects that ordinarily do not allow node editing. For example, MapInfo Pro does not allow you to add nodes to rectangle objects; however, if you convert a rectangle to a polyline, you can then add nodes to the polyline.

To convert objects into polyline objects:

1. Make the Map window active.
2. Choose the layer containing the objects and make it editable.
3. Select one or more objects from the editable layer.
4. On the SPATIAL tab, in the Edit group, click Convert to Polylines.

When you choose Convert to Polylines, MapInfo Pro converts each of the selected objects into a polyline. Each object is converted into a separate polyline; MapInfo Pro does not combine all selected objects into one polyline.

Line, arc, ellipse, rectangle, rounded rectangle and region objects may all be converted to polylines. The Convert to Polylines command does not affect point objects, text objects and polyline objects.

Changing the Default or Preference Setting for Calculations

Specifying Buffer Calculations

## Specifying Distance, Length, Perimeter, and Area Calculations for a Particular Map

To specify distance, length, perimeter, and area calculations for a particular map:

1. On the MAP tab, in the Options group, click Map Options to open the Map Options dialog box.
2. Choose a calculation method from the Distance/Area using option:

Spherical: Spherical calculations are used for distance methods that attempt to keep the measurement on the curved surface of the earth. The data is first converted to Latitude/Longitude and then a calculation is produced. Non-earth data cannot use spherical calculations, since the data cannot be converted to Latitude/Longitude.

Cartesian: Cartesian methods are used to perform calculations on Non-earth data. Cartesian coordinates are a pair of numbers, (x, y), defining the position of a point in a two-dimensional space by its perpendicular projection onto two axes that are at right angles to each other. Cartesian calculations cannot be used for Latitude/Longitude data, which is not a flat projection.

3. Click OK.

The only calculations available for the map Window's projection are those that will produce a valid result. For example, Cartesian is not available for a Latitude/Longitude projection because it cannot be use on a curved surface. Spherical is not available for a table in a non-earth projection because it is not curved and cannot be converted to Latitude/Longitude.

Note: When a Map window is first opened, it uses the setting from the preference as the default. Map windows saved in a workspace will save this setting, which will be re-sorted when the workspace is opened.