矢量化地图的配准

MapInfo Products KnowledgeBase



Product: MapInfo
Version: 7.5
Platform: All Windows Platforms
Category: Tools

Summary:
Using the Register Vector Tool to re-project non-earth tables.

Question:
When trying to add an imported file to a map window such as ESRI Shape (.shp), ArcView (e00), or AutoCad (dxf or dwg), or any other table with a projection that is Non-Earth, the map objects do not line up with other tables in the map window.

What is the cause of this problem, and is there a way to make the tables line up with each other?

Answer:
Files that do not line up after importing them through Table>Import, translating them with the Universal Translator, or opening through File>Open and choosing ESRI (R) Shapefile (*.shp), usually have a non-earth coordinate system associated with them. Dxf and Dwg files usually do not have earth projections associated with them, and if the projection system of an ESRI Shape file or ArcView file is unknown or not chosen, the Universal Translator will bring the files in as non-earth.

Any file with a non-earth coordinate system needs to be referenced to a real world coordinate system, such as Longitude/Latitude, UTM, State Plane, etc., in order to correctly overlay with other files.

In MapInfo Professional version 7.5 and higher, the Register Vector tool can easily accomplish this task by matching known locations in both earth and non-earth tables and applying a transformation to the non-earth coordinates.

Starting with a map of state boundaries, this example will use the Register Vector tool to transform the coordinates in a table named WYctyNonEarthMeters.TAB, which has a non-earth projection and consists of counties in Wyoming. The Universal Translator was used to create the table from an AutoCad .dxf file using the UT’s default non-earth projection.

Map of Non-Earth county polygons for Wyoming (WyctyNonEarthMeters.tab):



Map window containing polygons representing states (Earth projection = Longitude/Latitude NAD 27 for Continental US):



1. Have all files open including the non-earth table. Choose Tools>Tool Manager and check the Loaded box next to the Register Vector Utility. Click OK. Then, choose Tools>Register Vector>Register Vector Map to run the tool.

2. In the upper dialog, select the non-earth table to transform, WYctyNonEarthMeters in this example. In the lower dialog, select the map window that will be referenced. The reference window contains the layers that the WyctyNonEarthMeters table needs to line up with.



3. In the upper dialog, click on the Zoom Out button and use the zoom tool to view the entire WyctyNonEarthMeters table to see all the polygons.



4. By using the Zoom In, Zoom Out, and Pan tools, focus the map of the counties on a portion of the objects that can be easily referenced to the map window in the lower dialog.

Do the same for the map window in the lower dialog so that the corner of the Wyoming state polygon is in focus.

Once that is done, the upper left corner of the county table and the upper left corner of the polygon representing Wyoming State will be the starting point.



5. In the upper dialog click on the Select button. Then, click on the Snap button, which will show a dotted cross when using the select tool and help locate nodes for more accurate placement. Then, click on the Place Control Point 1 button.

Now, click on the corner node of the WyctyNonEarthMeters county map. This will drop Control Point 1 for the non-earth table.



6. Do the same to drop Reference Point 1 in the lower section of the dialog.



Notice that once Control Point 1 and Reference Point 1 are dropped, the button’s title will be replaced with “Place Control Point 2” or “Reference Point 2” and will be ready for placement of the next points.

7. Pan the upper map to focus on the lower left of the county table, and pan the lower map to focus on the lower left of the polygon that represents the state of Wyoming to line them up for placement of the Control Point 2 and Reference Point 2.



8. Repeat this process to place Control Point 3 and Reference Point 3. The lower right corners have been used in this example.



9. Click finish. A status bar may flash briefly and the cursor will turn to an hourglass as the tool transforms the coordinates and creates a copy of the WyctyNonEarthMeters county table. When the “Save Translated Table As...” dialog opens, give the copy a new name and save it to a folder.



10. Click Save. Once saved, the original non-earth table will be closed and the newly copied, registered table will be opened and automatically placed in the Map Window used for reference. The projection of the newly registered table will match the Earth projection of the Map Window used for reference.






Last Modified:
Document URL: http://testdrive.mapinfo.com/techsupp/miprod.nsf/kbase_by_product/EB5DA6D8A0C35EDD85256E430068926E
Using the Register Vector Tool to re-project non-earth tables.^EB5DA6D8A0C35EDD85256E430068926E^Y
posted @ 2005-04-08 16:22  jetz  阅读(3094)  评论(2编辑  收藏  举报