Overview of the Orion molecular cloud complex. Left: optical image of the Orion region (orientation roughly equatorial). Captured from deep in the heart of the Kalahari desert by Chris Beere (https://www.astrobin.com/users/chrisbeere. Color in this optical image is as shot with custom white balance, processed with Starnet++ to highlight extended structures). This image highlights well the interplay between the large-scale nebula and the dusty structures. L1622 shows a large tail of scattered light that is clearly distinct from the background. Right: overview of the studied subregions in galactic orientation. The gray-scale shows regions of high extinction from a 2MASS near-infrared extinction map (NICER, Lombardi et al. 2011) (A_K-range shown from 0 to 1.4 mag). The blue contours are smoothed extinction contours (at A_K = 0.42 mag), only shown for the molecular clouds of interest. The colored circles are the center locations of the selected 14 subregions within the three main regions: Orion A (blue), Orion B (magenta), and the two outlying cometary clouds (green, the green circles hide the blue contours of the small cometary clouds). Additional regions are labeled for completeness in gray. The color-scaling of the filled circles is used throughout the paper to identify the subregions within the clouds.