Grouping Objects using multipoint and collection object types


Grouping Objects using Multipoint and Collection Object Types
The Multipoint and Collection object types allow you to group multiple objects into a single object. One way to create multipoints and collections is by using the Combine command (on the Objects menu, click Combine). These object types aid in the translation and live access of other GIS data formats, such as ArcView Shape Files, and are more compatible with GIS standards. This is particularly useful for sharing maps with others using different software.
A Multipoint object consists of a number of points that have been grouped into a single object. The Multipoint object displays in a Browser window as a single record, and all the points within the object have the same symbol. One method you can use to create a multipoint object is to select a group of point objects and combine them.
A Collection object consists of multipoint objects, zero or one polyline objects, and zero or one region objects that have been grouped into a single object.
MapInfo Professional automatically converts homogeneous Collection objects to a more specific type, for example, a Collection object that contains only polylines is automatically converted to a multi-polyline object.
To create a Multipoint or Collection object using Combine:
Make the layer that you are going to select from editable if it is not already.
Select the objects you want to combine.
On the Objects menu, click Combine. The Data Aggregation dialog box displays.
Note Text objects cannot be used as input in a Combine operation.
Select the column(s) that you want to use in the aggregation and an aggregation method.
Click OK. The objects are combined into a single object.
Any point objects selected are combined to form a multipoint object. Any polyline objects selected are combined to form a a new region object. The resulting multipoint (if one exists), polyline (if one exists) and region (if one exists) are grouped together to form a new collection object.
For an existing multipoint or collection object, you may need to change its styles or view the bounds information. To do so, either double-click the object, or right-click the object to display the shortcut menu and choose Get Info. The Object Info dialog box for the selected object displays. If the object is not editable, the controls in the Object Info dialog box are read only

The Object Info dialog box for the selected object displays. If the object is not editable, the controls in the Object Info dialog box are read only.

In multipoint objects, you can change the style of the symbol that represents the multipoint. Click the Style button to display the Symbol Style dialog box.
In a collection object, you can change the styles of the different object types in your collection. Click the corresponding Style button for each object type you want to change.

Combining Objects with Multipoint and Collection Objects
The Combine command makes use of the Multipoint and Collection object types introduced in MapInfo Professional 6.5. You can use Points, Multipoints, and Collections as input in a Combine operation.
In addition, heterogeneous combines are possible using any combination of input objects, including Multipoints and Collections.
Note Text objects cannot be used as input in a Combine operation.
The result of such a Combine is a Collection object.
Multipoint Objects
If you are combining point or Multipoint objects, the Combine operation produces a single Multipoint object comprising all input points. Combining points is similar to other Combine operations in that the symbol style of the resulting object is the same as that of the first object to be combined. This object is normally the first object, in row order, of the table being combined.
Specifying Multipoint Object Attributes
A multipoint object is the result of combining points into a single object. The multipoint object must be editable (reside in an editable layer) before you can specify attributes.
Choose Map > Layer Control. The Layer Control dialog box displays.
Select the layer containing the multipoint object.
Check the Editable box.
Click OK.
Do one of the following to access the Multipoint Object dialog box:
Select a multipoint object. Press F7 to display the Multipoint Object dialog box.
Double-click the MultiPoint object. The Multipoint Object dialog box displays.
Select a multipoint object. Choose Edit > Get Info. The Multipoint Object dialog box displays.
Specify attributes for the multipoint object.
Click OK.
Collection Objects
The result of a Combine operation that uses heterogeneous object types as input is a Collection object. The input objects of a Collection object can be a mix of any of the following:
Point or multipoint objects (zero-dimensional)
Linear objects – lines, polylines, and arcs (one-dimensional)
Closed objects – regions, rectangles, rounded rectangles, and ellipses (two-dimensional)
Collection objects
Heterogeneous Combine operations take place in stages. First, all objects of the same dimension are combined separately. The Combine operations are done in the following manner:
All point and Multipoint objects, as well as the Multipoint component of any Collection object in the input are combined into a new Multipoint object.
All line, polyline, and arc objects, as well as the polyline component of any Collection objects in the input are combined into a new polyline object.
All regions, rectangles, rounded rectangles, and ellipses, as well as the region component of any Collection objects in the input are combined into a new region object.
Note As in other Combine operations that involve rounded rectangles, all rounded rectangles are treated as rectangles.
The resulting Multipoint, polyline, and/or region objects are then assembled into a new Collection object.
The styles for the new Collection object are derived from the styles of the separate Combine operations. These styles are assigned according to the style of the first object, in row order, of the table being combined. Keep in mind that the row order of an object may have nothing to do with the order in which you selected the objects for the Collection.
For example, the style of a Multipoint component of a Collection object is the style of the first point, Multipoint, or Multipoint component of a Collection encountered in row order. The style of a polyline component of a Collection object is the style of the first linear object or polyline component of a Collection encountered in row order. The style of a region component of a Collection object is the style of the first closed object or the region component of a Collection encountered in the input, in row order

Working with Coordinate Systems and Projections
Maps at their base are a visual representation in two dimensions of a section of the three-dimensional Earth. Being able to use maps in an electronic format in many ways frees us from the constrictions of the two-dimensional map because we can use mathematical formulas to compensate for the curvature of the Earth. In this chapter, we cover the coordinate systems and projections that are standard in MapInfo Professional and provide the tools with which you can create a custom projections to meet your organization’s needs. Whether you are a local government trying to establish new tax rolls or a large company trying to define your sales territory more precisely, creating a custom projection may be a solution you want to explore.
Topics in this Section:
Working with Coordinate Systems
Building Blocks of a Coordinate System
Adding Projections to the MAPINFOW.PRJ File
Understanding Precision in MapInfo Professional
Understanding Affine Transformations
Using Earth and Non-Earth Maps
Using the Ocean and Grid Tables
Frequently Asked Projection File Questions
Working with Coordinate Systems
The terms “projection” and “coordinate system” are often used interchangeably, however they do not mean the same thing.
Projection – An equation or set of equations that contain mathematical parameters for a map. The exact number and nature of the parameters depends upon the type of projection. You can think of a projection as a method of reducing a map’s distortion caused by the curvature of the Earth, or more precisely, a projection compensates for the shortcomings of depicting maps in two dimensions when the coordinates exist in three dimensions.
Coordinate System – When parameters of a projection are assigned specific values, they become a coordinate system. A coordinate system is a collection of parameters that describe coordinates, one of which is a projection
Displaying Coordinates
There are two places where coordinates display:
In the Status Bar by cursor location (set in the Map Options dialog box or by clicking on the Status Bar).
In dialog boxes that display area measurements, such as a Point Object, Region Object etc.
Note Coordinates can only be entered in the Object Info dialog boxes when a layer is editable.
You can display coordinates in one of the following formats:
Decimal degrees (e.g., 75.123456 degrees);
Degrees, minutes, seconds (e.g., 75 degrees 12′ 48″)
Military Grid Reference (WGS 1984 datum e.g., 41VLG3270555205 for 60 degrees longitude and 60 degrees latitude).
The default is Decimal degrees
Elements of a Coordinate System
A coordinate system in MapInfo Professional is made up of many elements which need to be specified in advance. Once these elements are in place, you can be sure that your maps are as accurate as possible. These are the projection elements you need to set in the MAPINFOW.PRJ file:
Projection Types
Datums
Units
Coordinate System Origin
Standard Parallels (Conic Projections)
Oblique Azimuth (Hotine Oblique Mercator)
Scale Factor (Transverse Mercator)
False Easting and False Northing
Range (Azimuthal Projections
Note For datum and unit tables, see Projection Datums and Units.


Understanding Coordinate Systems
You can make a map out of any globe without distorting the points on the surface by placing the globe into an imaginary cylinder.
Figure: Globe with Longitude/Latitude Projection

If you transfer the touch points from the globe surface onto the cylinder and roll out the cylinder onto graph paper, the result is a map as in the figure below. In the map that would be created from this cylinder, the Equator is 0 degrees all the way around the globe and the points on that line are completely accurate.
Figure: Longitude/Latitude Projection Map

When you add longitude and latitude lines at 15 degree increments to each side of the Equator and the Prime Meridian you create a reference grid. The lines furthest from the Prime Meridian are +180 degrees toward the right and -180 degrees to the left. This map projection is commonly called the Longitude/Latitude projection.
This is often considered the default projection. It is the most effective map for areas nearest the Equator but measurements further away tend to increase in distortion.
Because many people do not live near the Equator, other projections came into use to create more accurate local maps. Accuracy depends upon how you project the globe onto the cylinder. If you turn the cylinder so that it touches the Prime Meridian instead (or any line of longitude, 90 degrees away from the Equator) you have a Transverse Projection. The closer you are to the place the cylinder touches the globe, the more accurate the measurements are.
Figure: Globe Demonstrating the Transverse Projection

Transverse projections allow us to make maps that are more North-South line accurate, as long as you compensate for the distance from the new “Equator” which in this case is the Prime Meridian.
Figure: Transverse Mercator Projection Map

A third type of projection attempts to resolve the distortion problem in another way. Conic projections use a cone shape instead of a cylinder to create the “touch points” .
Figure: Globe with Conic Projection

This type of projection is much more accurate for large regions or countries that are wider in the East-West direction than in the North-South direction. There is much less distortion regionally because the touch points of a cone are closer to the map surface than those of a cylinder.
Figure: Brazilian Polyconic Projection Map

As you can see from the previous figure, the conic maps are best for small regional areas. The larger-scale map has too much distortion to be useful.
A fourth type of projection, the Azimuthal projection, does not use cones or cylinders but a simple circle that goes all the way around the globe over a particular point. This projection provides a “view from space” over a particular point.
Figure: Globe with Azimuthal Projection

This type of projection is most useful when you need to work with a particular hemisphere. A hemisphere need not be North-South or East-West based. The next figure uses the North Pole as the center point for the Azimuthal Projection.
Figure: Lambert Azimuthal Projection Map

You can use more than one projection that rotates a cylinder slightly along the Equator. This style is used in the Universal Transverse Mercator (UTM) projection. UTM maps the Earth with a transverse cylinder projection to create standard “UTM Zones”. By rotating the cylinder around the globe in six degree increments, the UTM assures that all spots on the Earth are within 3 degrees of the center line. (The Gauss-Kruger system is a European system akin to UTM that also uses a transverse cylinder rotated in six degree steps).
Figure: Universal Transverse Mercator Projection Map (UTM Zone 29)

Almost all projections you will use are one of these types. They are either cylindrical (regular or transverse), conic, or azimuthal projections and are customized by slightly different projection parameters. Projection parameters are options that describe how the projection is arranged.
You can further customize projections by specifying different parameters for the projection you want to use. For example, you can specify the longitude and latitude of any point on the Earth to create your own Azimuthal projection of that point. You can customize conic projections by specifying the parallel of latitude at which the cone should be tangent

Building Blocks of a Coordinate System
In this section, we provide the tables required to create your own coordinate systems using map projections, datums, units, Origins, Standard Parallels, Azimuths, Scale Factors, False Eastings, False Northings, and Ranges. You might want to create your own coordinate system if accuracy is crucial to understanding your data or if your data is specified in relation to a non-standard point, and you would prefer to keep your data in that custom coordinate system
Coordinate Systems, Projections, and their Parameters
By specifying a projection type and various required parameters, you create a mathematical algorithm for producing equivalent coordinates in degrees for the projected coordinate system. Each projection has specific parameters you can customize to make your maps more geographically accurate. The following table details each major coordinate system type and the parameters you can use to customize that system. The parameters are listed in the order they appear in the relevant projection entries in the MAPINFOW.PRJ file. To create your own coordinate system using a particular projection, you must add an entry into the MAPINFOW.PRJ file.
The parameters of a coordinate system are (in this order):
Coordinate System Name
Projection Type
Datum
Units
Original Longitude
Original Latitude
Standard Parallel 1
Standard Parallel 2
Azimuth
Scale Factor
False Easting
False Northing
Range
Note Each of these headings is described in detail in the next few pages.
For a complete list of common coordinate systems and their necessary parameters, see Projections and Their Parameters

Creating a Report of your Data
MapInfo Professional includes the full report-writing functionality of Crystal Reports. Crystal Reports enables you to create reports of your tabular data. The Crystal Reports User Guide is included online so that you can get the most from this program.
To create a report and print it:
On the Tools menu, point to Crystal Reports and click New Report. The New Report dialog box displays. It lists all the open tables.
Click the table you want to create a report for, and click Report. The Crystal Reports user interface displays.
In Crystal Reports, Choose Report > Report Expert to display the Create Report Expert dialog box. The Report Expert walks you through the selection of data, fields, fields to sort by, fields to total, and styles for your report. Click Preview Sample to see a sample of your report on the screen.
On the File menu, click Print to print your report.
Note Tables with columns containing underscores, temporary column, do not display in the default Crystal Report. Use the Expert Wizard to access columns containing these elements.
Opening an Existing Report
To open an existing report:
Choose Tools > Open Report. The Choose Crystal Report dialog box displays.
Select the report from the dialog box


Open Report command (Tools > Crystal Reports menu)
What is the purpose of Open Report?
Open Report displays the Choose Crystal Report dialog box. This dialog box allows you to choose and open a report that was created using Crystal Reports.
When is Open Report active?
Open Report is active when Crystal Reports has been installed.
How do I access Open Report?
To access Open Report:
Choose Tools > Crystal Reports > Open Report.