was needed to obtain chromospheric features in the emerging intensities. In the present study, we are analyzing an active region, and we wanted to assess the importance of horizontal scattering compared to the quiet-Sun case.

Figure \[fig:halpha\_1d\_vs\_3d\] shows the comparison between the vertically emergent intensity in 1D and 3D using our active region snapshot. The 1D computation shows chromospheric structures and traces of the large-scale structures, but much less enhanced than in the 3D case. We note that an imprint of the photosphere is still visible through the fibril-like structures in the 1D case, but not as prominent as in the quiet-Sun case.

The brightest features have a similar morphology in the 1D and 3D computations. Analysis shows that this is caused by the high mass density, and thus strong collisional coupling of the source function to the temperature, in the chromosphere at these locations (see Sec. \[sec:flare\_profiles\]). Therefore, this can potentially open the possibility to include [H$\alpha$]{} in inversions that assume 1D geometry in active regions.

Observations {#sec:observation}
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We use two different observational datasets to compare with the synthetic data. The first dataset is an observation of active region NOAA 12593, located near to the disk center at 