detecting "deformed" lines
The cross shape that i see in this example seems to remain more or less orthogonal. Maybe using a houghlines transformation with a piecewise flexibility might provide more true positives, but this also increases the false positives. In this case a corner detector might also be a goodidea, thus providing a set of interest points to search from and eliminate. The problem again there would be the large number of false positives. Try this morphological corner detector (Robert Laganiere (1998): "Morphological Corner Detection") - its simple and structural. The problem in such cases is classifying your background on which the cross falls to help improve with the false positives!