Control Point Registration using matlab -'fitgeotrans' function

Question

I'm new to Matlab and I'm trying to do a Control Point Registration using their guide: http://www.mathworks.com/help/images/point-mapping.html

It works fine until the 'fitgeotrans' function where I get an error that saying: 'Undefined function or variable 'input_points'.

I read the Matlab help and the previous "cpselect" function gives me two nX2 arrays with the coordinates which are saved (by the 'cpselect' function) in two array variables 'input_points' and 'base_points'. So, I really don't understand why the next function can't "See" them and considers them 'Undefined'.

My code is attached bellow. Thank you for your help.

function [Y] =EBL

ReferenceImg=imread('GFI.jpg');                          %This is the fixed image
CroppedImg=imcrop(ReferenceImg);                         %Crop the image
close                                                    %close the imcrop window
ResizedIReferenceImg= imresize(CroppedImg,[1000 1000]);  %re-size the fixed image

t=imagesc(ResizedIReferenceImg);                         %Set transparency of fixed image
set(t,'AlphaData',0.5);
hold on

I = imread('GF.bmp');                                    %This is the moving picture
MovingImg = imrotate(I,-5,'nearest','crop');             % Rotate the moving picture cw 

ResizedMovingImg= imresize(MovingImg,[1000 1000]);       %re-size the moving image
h=imagesc(ResizedMovingImg);                             %Set transparency of moving image
set(h,'AlphaData',0.6);
close

cpselect(ResizedMovingImg,ResizedIReferenceImg);         %Alignment
tform = fitgeotrans(input_points,base_points,'NonreflectiveSimilarity');

nkjt nkjt · Accepted Answer · 2014-10-01T12:29:47

The problem is that MATLAB doesn't, by default, wait for you to be done before moving on from cpselect. So it simply moves on from cpselect to tform before you have a chance to actually select any points, at which point input_points doesn't yet exist. You have to set the Wait parameter, and doing so also affects the outputs. With Wait on, call cpselect something like this:

[input_points,base_points] = cpselect(MovingImg,ReferenceImg,'Wait', true);

When calling cpselect in this way, you will not have the "Export Points to Workspace" option. Instead, the selected points will be output into the variables input_points,base_points when the cpselect window is closed.

Control Point Registration using matlab -'fitgeotrans' function

1 Answers