Extract valid control point pairs from
Read an aerial photograph and an orthoregistered image into the workspace.
aerial = imread('westconcordaerial.png'); ortho = imread('westconcordorthophoto.png');
Load some preselected control points for these images.
load westconcordpoints whos
Name Size Bytes Class Attributes aerial 394x369x3 436158 uint8 fixedPoints 4x2 64 double movingPoints 4x2 64 double ortho 366x364 133224 uint8
Open the Control Point Selection tool, specifying the two images along with the predefined control points.
cpstruct structure. Using the Control Point Selection
tool, select Export Points to Workspace from the File menu to save the points to the workspace. On the Export Points to Workspace dialog box, check the Structure with all points check box, and clear Moving points of valid pairs and Fixed
points of valid pairs. Click OK. Close the Control
Point Selection tool.
cpstruct2pairs to extract the moving
and fixed points from the
[mPoints,fPoints] = cpstruct2pairs(cpstruct);
Compare the stored set of points with the set of points you exported.
fixedPoints = 164.5639 113.2890 353.5325 130.0798 143.4046 284.8935 353.5325 311.9810 fpoints = 164.5639 113.2890 353.5325 130.0798 143.4046 284.8935 353.5325 311.9810
The two sets of points are identical, which indicates that all points in the stored set of points belong to valid control point pairs.
cpstruct_in— Preselected control points
Preselected control points, specified as a structure (
information about the x- and y-coordinates
of all control points in the moving and fixed images, including unpaired
and predicted control points.
unmatched and predicted control points, and returns the set of valid
control point pairs.
cpstruct_in is a structure produced by
the Control Point Selection tool (
when you choose the Export Points to Workspace option.
For more information, see Export Control Points to the Workspace.
movingPoints— Control point pairs from moving image being aligned
Control point pairs from image being aligned, returned as an m-by-2 numeric array. The two columns represent the x- and y-coordinates of the control points, respectively, in the intrinsic coordinate system of the image.
fixedPoints— Control point pairs from reference image
Control point pairs from reference image, returned as an m-by-2 numeric array. The two columns represent the x- and y-coordinates of the control points, respectively, in the intrinsic coordinate system of the image.