Transform By Point Pairs

This tool converts a set of points or elements from one coordinate system to another. For example, from a Local coordinate system to a geographic coordinate system. By selecting points that have their coordinates values in both the source and the target coordinate systems. Transform takes place by translating, rotating, and scaling depending on the transform method selected from the available list.

Access this tool from the following:

Ribbon: Survey > Edit > Edit Linear > Transform by Point Pairs

Ribbon: Geometry > Common Tools > Transform by Point Pairs

Figure 1. Transform By Point Pairs Option

Select the Point Pairs button. Transform by Point Pairs Tool dialog is as given below.

Figure 2. Transform by Point Pairs Tool Dialog
Parameters Description
Refresh Points 		Refreshes the point list if selected items change.
Include Points 		If ON, you can select items from a reference file. If OFF, it will not allow selection from a reference file.
Enable Fit View 		If ON, it will fit the source or target, depending on what is selected, to the view.
Enable Centre View 		If ON, it will center the source or target, depending on what is selected, to the view.
Hide Locator 		If ON, it will show a locater at the source and target point for the row selected.
Hide Decoration 		If ON, it will show the decorations (temporary annotations) at the source and target.
Show XY 		If ON, it will show the X and Y values in the dialog.
3D Transform 		If ON, it will perform a 3D transformation based on source and target elevations.
Do Not Use Weights 		If ON, it will apply Weights when performing a transformation. The higher the weight the more influence it has on the transformation.
Transform

Allows you to select transform options mentioned below:

  • None
  • Affine 1d Two Param
  • Affine 2d Six Param
  • Affine 2d Six Param Iterate
  • Helmert 2d Six Param
  • Helmert 3d Seven Param Iterate
  • Least Squares 2d Four Param
  • Conformal 2d Four Param Iterate
  • Projective 2d Eight Param Iterate
  • Rigid 3d Six Param
Figure 3. Transform Options
  • Affine 1d Two Param: This transformation will move and scale, with one scale factor, the source in the horizontal plane. It requires a minimum of 1 point pair.
  • Affine 2d Six Param: This transformation will move, rotate, and skew the source in the horizontal plane. It will apply a scale for the x and the y separately. It requires a minimum of 3-point pairs.
  • Affine 2d Six Param Iterate: This transformation will move, rotate, and skew the source in the horizontal plane. It will apply a scale for the x and the y separately. It requires a minimum of 3-point pairs.
  • Helmert 2d Six Param: This transformation will move, rotate, and skew the source in the horizontal plane. It will apply a scale for the x and the y separately. This transformation will require a minimum of 3-point pairs.
  • Helmert 3D Seven Param Iterate: This transformation will move, rotate, and scale, with a single scale factor, the source in the horizontal & vertical plane.
  • Least Squares 2d Four Param: This transformation will move, rotate, and scale, with a single scale factor, the source in the horizontal plane. This transformation will require a minimum of 2-point pairs.
  • Conformal 2d For Param Iterate: This transformation will move, rotate, and scale, with a single scale factor, the source in the horizontal plane. This transformation will require a minimum of 2-point pairs.
  • Projective 2d Eight Param Iterate: This transformation will move, rotate, and skew the source in the horizontal plane. It will apply a scale for the x and the y separately. It requires a minimum of 4-point pairs.
  • Rigid 3d Six Param: This transformation will move and rotate the source in the horizontal & vertical plane. It requires a minimum of 2-point pairs. The only method that will not scale and skew is "Rigid 3d Six Param".
Figure 4. Source & Target Area

  • Source area and controls. (Red box)
  • The source area contains the source points (the points you want to transform)
  • Include: If OFF the point pair will not be included in the transformation.
  • Target area and controls. (Green box)
  • The target area contains the target points (the points you want to transform to).

The following menu is displayed by right-clicking on the main dialog:

Figure 5. Element Selection Dialog
Source Tool
Select Source Element 		Allows you to select the Source element or elements.
Select Source Point 		Allows you to graphically select a source coordinate to change the coordinates to the Source point.
Add New Pair 		Allows you to add a new point pair to the transformation.
Edit Selected Pair 		Allows you to edit a selected point pair. Prompts are given in the taskbar.
Delete Row 		Allows you to delete a selected point pair.
Delete All Rows 		Allows you to clear all point pairs.
Target Tools
Select Target Element 		Allows you to select a target element or elements.
Select Target Point 		Allows you to select and edit a target point.
Move Target Point Up 		Allows you to move the target point up.
Move Target Point Down 		Allows you to move the target point down.
Clear Target Point 		Allows you to clear the selected target point.
Clear All Target 		Allows you to clear all target points at once.
Show Results 		Allows you to view the results of the Transformation.

The Transform computed results for the point pairs selected are shown in the output section of the dialog. A higher Weight Count allows to hold a point coordinate closer to the target value.

The "Select" button will allow the user to select the points or elements that are going to be Transformed from one system to another. A selection set can be used before pressing "Select" by selecting the elements with the "Element Selection" tool.

Figure 6. Transform By Point Pairs Result

To operate the command first select your Source element(s) and then select the appropriate target element(s). Turn on the point pairs you would like to include.

Options Description
Save 		Allows you to save the transformation results to a text file.
Copy 		Allows you to copy the transformation results to the clipboard.
Clear 		Allows you to clear the transformation results.
On/Off Information 		Allows you to turn on and off certain information in the transformation results