VERIFIED SOLUTION i

Thinning Nodes using MapInfo Pro

Product Affected: MapInfo Pro™
 
User's sometimes need to thin or remove nodes from a polygon to resolve issues and/or increase performance.
Thinning attempts to remove nodes (which define vector-based map objects) to increase performance or solve other spatial issuers, as an excess of nodes can negatively affect spatial joins, combines, etc. and affect performance as a whole regarding panning, zooming, etc.

Before thinning a table, the layer in the map must be made editable. Place a check in the "editable" checkbox for the layer to be thinned.

Turning the display of nodes on or off for a particular layer in a map can be accomplished by clicking on the display button and putting a check in the Show Nodes check box. (This display option does not have to be on for the Thinning process to work. It is merely for display purposes only.)

Make the table editable and then select the object(s) to be thinned . This can be accomplished by using the select tools located in the Main tool bar  or SQL Select. In this example, select all the objects using Query>Select.

Choose Map > Selection > Query Select. In the Select dialog, select the table from the table drop-down, and uncheck the "Browse Results" option and Click OK.
In MapInfo Pro 64-bit, users can also right-click on the desired layer to be thinned in Explorer/Layer Control and choose "Select All".

Now that the objects are selected, the thinning process can be started.
Choose Spatial > Edit> Fix/Clean > Snap/Thin and place a check in the Enable Node Thinning/Generalization check box.
A simple test approach would be to set the Distance Units to be Meters and enter a value of 100 meters for both 3-Node Collinear Deviation and Node Separation (For more information regarding the 3-Node Collinear Deviation and Node Separation settings, click the Help button)

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7. Click OK. If the resulting operation does not produce the desired results, undo or revert the changes to the table by choosing Table > Revert Table.

Before Thinning:

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After Thinning:

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The minimum triangle height required for the Thinning operation to leave a given 3-node triangle alone (not remove any nodes).
In other words -- take three consecutive nodes in a polyline or region, and draw a triangle with them:

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The blue line represents a section of the region or polyline to be thinned. If the height of the triangle (green line) is shorter than the 3-node Collinear Deviation setting (100 meters, in this case) then node 2 will be thinned out (removed), thus turning the triangle into a straight line. If the green line is longer than 100 meters, node 2 won't be removed -- the triangle is judged to be "significant", so it is left intact.

UPDATED:  July 30, 2019