Overview

• Topic: Editing lines and regions.
• Not discussing data management issues in general, label editing, digitizing table techniques, coordinate precision, ... [These could be future presentation topics].
• Focus will be on "Tricks, Tips & Traps"
• Your safety nets:
  -- [Esc] key;
  -- Edit > Undo;
  -- File > Revert Table; and
  -- Backups of your tables/files.

Setup & Getting Started

• Backup your original map tables!
   
• Display the layer to be edited along with any reference map layers. Adjust line/fill styles.
   
• Use Layer control > Display to turn ON/OFF the line direction, node, and centroid indicators.
   
• Check/adjust "Move duplicate nodes" setting:
  - Use Options > Preferences > Map Window .
   
• Adjust “Snap” settings:
  - Push [S] key to toggle "snap" ON/OFF.
  - Use Options > Preferences > Map Window to adjust snap tolerance.
   
• Adjust the "Undo" preferences:
  Options > Preferences > System Settings (button) > Undo objects.
   
• Use a "Comment.tab" map layer as a scratch pad to note questions/issues.
   
• Keep your MapBasic window open as a log of your actions.
   
• Promise to Save tables often!

• Use the Region tool, not Polyline tool. Why?
  If you use the polyline tool, you have to take the separate step of converting the polyline to a region.
   
• Make or re-shape using *other* regions. Why? 
  This helps avoid slivers and results in exact registration. Use Table > Combine using column ... or Objects > Combine ...
   
• Draw roughly, then use the Reshape and Add Node tools to true-up the shape.
   
• Don't rule out the AutoTrace feature (for either regions or polylines): SNAP should be ON.
  -- Click on a node of an existing region to denote the start of the tracing;
  -- [Shift-Click] or [Ctrl-Click] where you want to stop the tracing.
  -- AutoTrace traces the segments between the Start and Stop nodes.
   
• To remove slivers and overlaps, consider Objects > Clean ...

QA/QC:

• Hover along the line “hidden” [Snap feature ON] to spot duplicate or missing vertices.
   
• Vertex is "invisible"? This means there are two vertices there. Move vertices temporarily to spot double-back errors.
   
• To spot detect overlapping regions:
  Option a: Use Layer Control > Display to assign a non-solid *transparent* fill pattern [un-check “Background”].
  
  Option b: Use Objects > Check region objects ... (MI Pro 6.0+).
   
• Specify a VERY thick line width. This helps identify stray, sometimes very short, line segments.
• To remove very small polygons:
  
  Option a: Use Objects > Disaggregate ... ;then Query > Select... This helps find tiny slivers or stray short lines. Cf. Functions: Area(obj, "sq km").
  
  Option b : Use Objects > Snap/Thin > Polygon area thinning. (MapInfo Pro 6.5+)
  Note that this evaluates the size of each small component polygon in a multi-polygon region--not the size of the region as a whole (This is good).
  

• Use the polyline not the simple line tool. Why? Consistency. Also, you can add nodes to a polyline (but not to a simple line) using the Add Node tool.
• Display line directional arrows to judge “From” and “To" (if working with street data)
  Use Map > Layer Control > Display …
• To change the line direction, consider the free Swap-Direction mbx (Routeware of Denmark) or ReverseDirection mbx (Arnold McRay of Canada, Author)
• Warning: If you split a street you still need to adjust the street addresses. A MapBasic utility could automatically assign address ranges to each piece.

QA/QC:

• To spot stray, sometimes very short, line segments:
  Option a: Display the line objects with a VERY thick line style (e.g., 6-pt).
  Option b: Use Objects > Disaggregate ... then Query where area is very small or length is very short. (MapInfo 6.5+)
• Check for records that have no line object:
  Use Select * from [tablename] where NOT obj

• Turn on the dynamic labels, specifying the new data column as the source of the labels.
• Avoid typing text directly into MapInfo where possible.
  e.g., Make a separate table for columns of data, including a unique ID value such as zip code number or Census Tract code. In your map table, only enter the appropriate ID# value. Join the two tables using Query > SQL_Select ...
• Where you can, select groups of map objects and update their data values all at once. E.g., use Table > Update Column ...

QA/QC:

• If column values should be unique (ie, one and only one record per zip code), verify that they are:
  Use Query > SQL Select ...
  Hint: Try the "Group By" parameter and the Count(*) aggregation function.
• Check for valid values and completeness by creating a thematic map. The colors will change in the map as you add or change data values.

Q: You make a layer editable, but when you try to edit it, you get the following error message:
"Cannot perform edit. Someone else it editing this table."
A: Look for temporary files called [tablename].tDA, [tablename].tMA, [tablename].tIN. Delete these if you're certain no one else is editing the table.

Q: Is there an "auto-save" feature that will save my work every ten minutes or so?
A: No.

Q: You have been editing for quite a while. When you try to Save, you get the following error message:
“Unable to save. Out of disk space while editing ...”
A. You may not really be out of disk space.
Use File > Save Copy As ... to save your work under a new name.
Use File > Open Table ... or File > Recent Files ... to open the saved table.
Use Table > Maintenance > Delete Table to permanently delete the problem table. [You may need to Revert Table before you can delete it.]

Q: How do I move the centroid of a region, for example to re-position where the label is automatically placed?
A. Use Layer Control to make the map Editable.
While in Layer Control, choose Display > Show Centroids ...
After exiting Layer Control, select the region and click on the "Reshape" tool button.
Note: For our own protection, MapInfo won't let us move a centroid out of its region.

Q. I have edited a region substantially, but my centroid hasn't adjusted itself accordingly. Or, I have moved my region centroid in error. How can I re-set it at the original spot?
A. Select the region then use Objects > Convert to Polyline; then Objects > Convert to Region.

Q. I have a chain of polylines that I want to convert into a closed region. That is, I have drawn several polyline in the shape of a closed region. When I use Objects > Convert to Region I get a bunch of small angular regions instead of one normal region.
A. Select all the polylines and make them a single polyline using Objects > Combine ... then re-try Objects > Convert to Region .
Q. I combined my polylines as you said, but Objects > Convert to Region still doesn't produce a single closed region.
A. Maybe your polylines don't truly connect. Zoom in tight on your polylines. Trying moving various nodes with the  Reshape tool, esp. at the ends of the polylines. (To make sure duplicate nodes move in concert, use Options > Preferences > Map Window ... )

Q. I can't seem to select a region, no matter how or where I click with the Pointer tool.
A.
First, are you *sure* it is a region? Try to select it with the Radius Select or Marquee Select tools.  If the object is a Line of Polyline, you must click on the line, right?
Second, are you sure the region *isn't* selected? Click on the Unselect All tool button, then try again. Refresh your screen with Window > Re-draw window then try again.

Q. At times, my Pan tool stops working, especially while I am doing map editing.
A. Turn off SNAP. There is a known issue or conflict between SNAP and the Pan tool.

1. You receive quarterly street map updates as part of a commercial data subscription. However, based on your local knowledge, you want to update the map, too.

2. Several people in your organization regularly need to update the same map layer, often at the same time.

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