Lab I Section I: Interactive Conversions

The Interactive Conversions screen of the Geographic Calculator is designed to complete coordinate conversions in an easy and convenient manner. The Geographic Calculator allows the user to convert coordinates from a comprehensive set of coordinate systems. The Interactive Conversions screen is divided into two identical sections. When performing a coordinate conversion, it is necessary to choose one side of the screen as the Source, or Input section. The remaining side becomes the Destination, or Output section. It does not matter which side is used for the Input or Output.

Object:

To convert a point in the Geodetic Latitude/Longitude coordinate system to US State Plane 1927 grid values, save it to a file, and print the conversion information.

Your project calls for coordinates to be stated in the US State Plane 1927 grid. The Geodetic Lat/Long coordinates that you have are:

SET UP CONVERSIONS FOR OUTPUT TO FILE

It is often desirable to record an interactive conversion for later reference or presentation. This function must be set up prior to the interactive conversion.

To set up the Geographic Calculator for recording the conversion:

1. Open the Geographic Calculator

2. Go to File Record Interactive Conversions...

3. Select a folder to save to and name your output log file "Interactive Log.txt".

4. Click Save.

The calculator will now record the following Interactive Conversion to the file that was just selected.

Follow these steps to complete an interactive conversion of this point:

INPUT PARAMETERS

1. Click on the Interactive Conversions job. This will bring the Interactive interface onto the screen.

2. Go to the Coordinate Point Definition area located on the left. This is going to be the Input side.

3. Place the cursor in the Name box and title the source point "A".

4. Enter the Lat/Long coordinates listed at the beginning of this lab into the North/ South and East/West boxes below the name box. Enter the Latitude value (N) in the Latitude (North/South) field and enter the Longitude value (W) in the Longitude (East/West) field.

   Latitude:	44 13 36.96 N
   Longitude:	69 46 08.11 W

5. To select your Input Coordinate System, double-click on the blue box labeled System in the left Coordinate System area at the bottom of the job page.  By default, the Calculator starts with the geodetic coordinate system of WGS84 selected.  This will launch the Select Coordinate System dialog:
   
   

6. In the Select Coordinate System dialog, coordinate systems are organized in the folder list on the left by type (Geodetic Lat/Long, Projected, Geocentric, and Fitted), continent, then by country.  If a coordinate system covers an entire continent, it will be found by clicking on the continent folder itself.   In the tree view on the left, browse under Geodetic>World, in the coordinate system list on the right, select WGS84 Coordinate System.
   
   

7. Select the format for your input point by going to the Coordinate System area and clicking on the Format control button.

8. A dialog box will appear.  Select the following parameter:

11. Leave the Vertical Reference field, set to  (none). There are no elevation parameters for this conversion.

OUTPUT PARAMETERS

The next few steps will be performed in the Output side of the screen. Remember: It is arbitrarily decided which side is used as the Input side and which side is the Output side.

12. Go to the side of the interface you have selected for output.

13. Type "B" in the Name box.

14. To select the output coordinate system, double-click on the blue box labeled System in the right-hand Coordinate System area at the bottom of a job page.  By default, the Calculator starts with the geodetic coordinate system of WGS84 selected.  This will launch the Select Coordinate System dialog.

15. To select the NAD 27 US State Plane, Maine West Zone, in the tree view on the left, browse under Projected>North America>United States>US State Plane NAD27; in the coordinate system list on the right, select Maine West 1802.  Then click OK.
    
    

16. Select the format for your output point by going to the Coordinate System area and clicking on the Format control button.

17. A dialog box will appear.  Select the following parameter:

18. The final setting before completing the conversion is to select the Datum Transformation used to convert the coordinates from the WGS84 datum to the NAD27 datum.  To do so, click the Select Datum Transformation button in between the two coordinate system selections.
    
    
    The Select Datum Transformations dialog will assist you in selecting an appropriate datum transformation for your coordinate by only displaying those shifts that have a suitable envelope (defined area of use).  The Transformations are listed in a tree view like other objects in the Geodetic Data Source.  Select the Nadcon category to see the only recommended transformation for the point you have entered.
    
    
    
    Select the transformation on the right panel and click OK.

CONVERSION

19. Click on the Calculate button to complete the conversion.

The results will appear in the destination area in the corresponding boxes:

These are the US State Plane Values for the Geodetic Lat/Long coordinates.

Example: Completed Conversion

The coordinate conversion is complete. The conversion data (Original point coordinates, output coordinates, conversion parameters, etc.) can be viewed in a text editor by opening the text file specified before the conversion.

Alternatively, the conversion data can be viewed and printed by going to FilePrint (or clicking the print button). The display can be changed to suit your needs.

Note:

You can save the conversion settings (Input and Output Coordinate System Settings) by going to FileSave As...>Job and naming an output file.  This saves all of the settings in the Interactive Job.  This file can be recalled and the parameters are automatically entered into the active dialog.