Optimal matched linear filter applied to realistic data. Left panel: the filter response on a mock catalog based on the N-body numerical simulation without noise and as a function of scanning angle. Each line represents the result for three different radial cutoffs. Right panel: this case considers the noise given by a finite source number density of n_s = 15 arcmin^-2 and an intrinsic ellipticity rms of σ_g = 0.4. The red line represents the expected theoretical signal (the same as in the left panel), the blue line the filter outcome for noisy data, and the dashed blue lines its ~ 1σ upper and lower uncertainty. The most significant filamentary structure (at α ~ 70 deg) has been recovered at the ~ 4σ level, all others are detected with a lower significance.