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Map Room Home page | |
written by Nigel
James
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MAPINFO How to... | |
No. 5: Create a basic point data map (Longitude/Latitude) | |
(References to tables, folders etc., are not applicable outside the Map Room, so if you are located elsewhere, you should substitute your own) | |
This explains how to use MapInfo to map point data. The example maps Mt. Everest and Mt. McKinley on a map of the World. We will then add Mt. Kilimanjaro and re-map the points. If you are mapping Ordnance Survey data points, see How to No. 6: Creating a point data map using OS grid references. Coordinates have to be converted to decimal degrees, as MapInfo does not recognise conventional degrees:minutes:seconds. Thiscan be done using Conversion Tools* in MapInfo after you have created your table. If you wish to create your table on another PC (in Excel for example) and bring it in on a disk, then see also MapInfo How to no. 12 Creating data files for use in MapInfo. |
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*The MapInfo tool Conversion Tools, referred to in this guide, can be downloaded from the geo_tools section of the Map Room website. There is a basic converter tool which ships with MapInfo but it is not as versatile as Conversion Tools. | |
1. Start MapInfo. 2. Create a new data table by opening the File menu and clicking New Table. In the New Table dialog, Open New Browser should be ticked and Open New Mapper unticked. Click Create. 3. You will now see the New Table Structure Dialog. Our table will have four fields: Name; Longitude; Latitude; Height. 4. In the Field Information group, enter the field name as Name. Leave type as character and set the width as 30 (the width must be at least the number of characters in the longest name). 5. Click the Add Field button to enter the next field. This will be the longitude. Enter the name as Longitude and select Character from the type list (as the coordinates will be a mixture of numbers and letters). Set the width to 15 (to allow for any spaces). 6. Click the Add Field button and create a field for Latitude in the same way as step 5, entering Latitude for the field name. 7. Click Add Field and enter the field name as Height and set the type to Integer (heights will be whole numbers). 8. The Table is mappable box should be unticked as the projection will be set when you convert the coordinates to decimal degrees with Conversion Tools. Click OK. 9. The structure is now complete, so click Create. Save the table as mountains.tab in your user folder. 10. Your table appears as a single row table (just the field names). If it does not appear, open the table in a browser window. 11. Now place the cursor on the row, hold down the Control key and press E to create a new blank row. We need two rows initially, so use Control + E again
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12. Now we can enter the data. 13. Enter the name of the first mountain (Mt. Everest) in the first field of the first row of your data table. 14. Tab to the latitude column and enter the latitude as 27:58N. Note the use of a colon to separate the degrees and munutes. You can add seconds as well if you have them, again separating them with a colon (e.g: 27:57:2N). 15. Tab to the longitude column and enter the longitude as 86:56E. 16. Tab to the height field and enter 29,028. 17. Now enter the name Mt. McKinley in the name field of the second row
and enter the coordinates (Lat. 63:2N and Lon. 151:1W) . Enter the height
as 20,320. |
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18. Save the table (File/Save table). Select your table in the Save Tables dialog and click OK. 19. The next step is to convert the coordinates to decimal degrees and create points. With the table open in MapInfo, open the Conversion Tools menu and click Table of Lon and Lat to decimal degrees. |
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20. The Table list in Conversion Tools will list all open tables. Select your table and all existing columns will be listed. Select the Longitude and Latitude columns and choose a symbol by clicking the Symbol button. If your table does not use a colon separator then enter the correct separator in the Separator box. | |
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21. If all is correct, click proceed to convert the coordinates and create symbols. When the conversion process is complete, the table will have two new columns, with the latitudes and longitudes in decimal degrees and a symbol for each record. 22. Now you can display the mountain points on a map. Open the File menu and click Open Table. We will use the MapInfo World outline map, so change to drive D, then open the MapInfo folder. Next open the Data folder, then the World folder. Open the table world.tab. Right-click on the map and click View entire layer from the menu to display the whole World. 23. With the World map displayed, open the File menu and click Open Table. Select your mountains table again, and also select Current Mapper in the Preferred View list. Click OK and the two mountains will be displayed on the map. 24. You can label the two mountains with their names by opening the Layer Control and ticking the Autolabel box for the mountains layer. Next, click the Label button and check that Name is selected in the label box. Click OK in each dialog until the map is redisplayed with the names. 25. You can also use the height to label the mountains, by opening the Layer control and clicking the label button, then selecting Height for the label instead. 26. Once you have created a points table and mapped it, you may wish to add further points. Although you can add them to the data table, they will not be added to the map, as the conversion process has to be re-run to add the new points. We will now add Mt. Kilimanjaro to the table. 27. If your table is not open in a browser window, open it now by opening the Window menu and clicking New Browser Window. Choose Mountains and click Open. Place the cursor in the browser window, then hold down the Control key and press e to add another row. Enter the name as Mt. Kilimanjaro and the coordinates as longitude 37:20E, and latitude 3:2S. The height is 19,340. 28. When you have entered the data, save the table, then run the Conversion Tools again to convert the new entry. The table will close when the process is complete, so open the table again to map the points again. 29. Removing points is the same process, but instead of adding a row, click the box to the left of the row to remove, then press the Delete key. They row will remain but will be blank. You can remove blank rows by opening the Table menu, then selecting Table Maintenance and then Pack Table. You will be warned that data may be lost, but as the row(s) are not required that doesn't matter. Click OK to pack the table (remove blank rows). The table will close after it has been packed, so you will need to re-open it again. |
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This is a brief and specific guide to this topic, for more general information, see: MapInfo - an easy guide for new users | |
Nigel
James
Bodleian Library 2003 |