XYRectify

XYRectify is a simple software application for 2D & 3D planar rectification. Designed to work seamlessly with output from iWitness/iWitnessPRO, or user-generated data. This software is free for all Photometrix customers, otherwise US$99.00 for a single-PC licence. For more information, please contact us.

XYRectify creates rectified images from oblique images of planar surfaces. This operation is often referred to in photography circles as “keystoning” or removing the keystone effect. It takes place, for example, when an image taken looking up at a building is transformed to one where vertical edges of the building become both parallel and ‘vertical’, as indicated in Figure 1. Whereas image scale is not homogeneous in the oblique or tilted image, it is homogeneous in the rectified image. This allows XY coordinates with consistent scale to be digitized in the rectified image. Shown in the figures below are oblique or tilted images (with respect to the plane of interest) and the corresponding rectified images for the planar surface of interest. Note in Figure 1 how in the rectified image the window frames are now parallel or orthogonal, and in Figure 2 the carpet is rectangular, as if viewed from directly above its centre.

Figure 1: Unrectified (left) and rectified image (right) of building façade.

Figure 2: Unrectified (left) and rectified image (right) of ‘Bailey’.

The XYRectify software manual can be downloaded here.