  Filament finders are limited, among other things, by the abundance of
spectroscopic redshift data. As there are proportionally more photometric
redshift data than spectroscopic, we aim to use photometric data to improve and
expand the areas where we can detect the large-scale structure of the Universe.
We present a proof of concept, showing that the Bisous filament finder can
improve the detected filamentary network with photometric redshift data. We
created mock data from the MultiDark-Galaxies catalogue. Galaxies with
spectroscopic redshifts were given exact positions from the simulation.
Galaxies with photometric redshifts were given uncertainties along one
coordinate. The errors were generated with different Gaussian distributions for
different samples. There are three different types of samples: spectroscopic
only, photometric only, and mixed samples of galaxies with photometric and
spectroscopic redshifts. In photometric-only samples, the larger the
uncertainty for photometric redshifts, the fewer filaments are detected, and
the filaments strongly align along the line of sight. Using mixed samples
improves the number of filaments detected and decreases the alignment bias of
those filaments. The results are compared against the full spectroscopic
sample. The recall for photometric-only samples depends heavily on the size of
uncertainty and dropped close to 20%; for mixed samples, the recall stayed
between 40% and 80%. The false discovery rate stayed below 5% in every sample
tested in this work. Mixed samples showed better results than corresponding
photometric-only or spectroscopic-only samples for every uncertainty size and
number of spectroscopic galaxies in mixed samples. Mixed samples of galaxies
with photometric and spectroscopic redshifts help us to improve and extend the
large-scale structure further than possible with only spectroscopic samples.
