When a set of density maps is inserted into the simulation from the paramfile, it can happen that the planes exist to higher redshift than the source plane at z_s. In this case, all planes (also with z > z_s) are inserted before the source plane. In the ray shooter, the light passes through all planes, giving those with higher-than-source redshift a negative sign for the convergence. The result is a kappa map that is clearly wrong, with a lot of negative values.
When a set of density maps is inserted into the simulation from the paramfile, it can happen that the planes exist to higher redshift than the source plane at z_s. In this case, all planes (also with z > z_s) are inserted before the source plane. In the ray shooter, the light passes through all planes, giving those with higher-than-source redshift a negative sign for the convergence. The result is a kappa map that is clearly wrong, with a lot of negative values.