Hi,
I am trying to use torch.nn.functional.affine_grid to generate a grid that will be passed to torch.nn.functional.grid_sample.
Consider:
+(1) Small square image of size (K,K)
+(2) Rotated Box defined by (x_center, y_center, w_box, h_box, angle) where x_center, y_center is in the coordinate system of the input image described below.  w_box is the width of the box and h_box is the height of the smaller image.  Angle is rotation applied to the box in degrees.
+(3) Input image of size (w_input, h_input).
The problem I am solving is to paste (1) into (3) such that (1) is rotated/scaled/translated to fit the rotated box defined in (2).
Any pixel that falls outside of the input should be discarded.  What is the 2x3 affine matrix that I should use to generate the affine grid?  Thanks.