How to use TFORMINV ?

I have just started to use Matlab's TFORMINV function. I have already looked up the documentation. I am trying to debug an issue in an existing code related to tforminv function.

When I run the code, I get the following error :

Error using tform>checkTform (line 89)
Function TFORMINV expected a TFORM struct as its first or second argument.

Error in tform (line 29)
[t, A] = checkTform(f, numout, varargin{:});

Error in tforminv (line 67)
varargout = tform('inv', nargout, varargin{:});

Error in train_detector>traversetree (line 357)
[pixel_a_x_lmcoord, pixel_a_y_lmcoord] = tforminv(tf2meanshape, pixel_a_x_imgcoord, pixel_a_y_imgcoord);

...

but, tf2meanshape seems to me of type TFORM. Here is the screenshot which shows that tf2meanshape is of type struct during debugging, but when I step into next line I am getting the above error :

Let me know if any additional information is required. Thanks in advance.

[David Young]

It's very hard to read the screenshot. Please can you post the code that produces tf2meanshape. Normally this would be the result of a call to maketform, but I think you must be making it some other way, perhaps using affine2d.

[Guru Swaroop]

you can right click the image, and select open image in new tab. In my system it is readable.

[David Young]

I can read the screenshot now, but I still can't see the code that produces tf2meanshape. It is an affine2d object, not a struct as required, so it's a question of whether you should be using maketform to make a struct instead, or whether you should be using its transformPointsInverse method to apply the transformation. You're not showing the code so it's hard to give advice.

Answer 1

[Guru Swaroop]

Thanks David, As you rightly pointed out, I had to use transformPointsInverse instead of tforminv.