Ideal infinite-extent targets are defined by templates that are not blurred, have prefect edges, and have no border (that is, at least part of the white target touches the edge of the template image). These are used to mark targets in photos that are part of a larger object and usually do not have a clear surrounding background. These targets are not sized to match the region being marked in the source image but instead they are extended. The pixels at the boundary of the target are replicated at infinitum as needed to match the source region being marked.
The program ships with a survey target (looks like two squares touching at one corner), an edge target, a corner target, and infinite cross. These infinite-extent targets cannot be used in auto-marking or tracking but still make useful tools in manual sub-pixel marking of corners, edges, etc.
When marking an infinite target it is important to choose an area that resembles the target template. If the template is infinite but the object being marked has a boundary the region selected should not include this boundary. For example when marking a survey target only the center portion of the target should be selected, extending to include the outside border of the squares may cause the target marking to fail.
A good use of an infinite target is the infinite cross. This target is well suited to marking grids of lines. In a grid the intersections are not isolated crosses but instead are part of larger lines. The infinite cross template can mark the intersection of these lines to high accuracy.