Field lines

A traced field-line view of the solution: a bundle of lines drawn in projection over the photosphere disk. The default look follows an eclipse photograph: the open fan seeded on the limb, short closed loops on the front face, lines coloured by the polarity of their inner foot, and the disk rendered as a B_r magnetogram from the data. Self-contained: it traces the field directly and does not use a built volume.

qorona fieldlines data/coconut_corona.CFmesh.xz -o data/fieldlines.png \
    --timestamp 2025-10-09T18:19:52 --fov 8 --longitude 317 --latitude 6.2 --seeds 1650

The flags that matter

• --seeding limb|uniform: limb (front loops plus the open limb fan, the default) or a uniform sphere; --seeds and --limb-seeds set the budgets.
• --colour polarity|rainbow: line colour by inner-foot B_r sign (default) or per-line hue.
• --magnetogram / --no-magnetogram: the B_r disk (default on).
• --show all|open|closed: which lines to draw (default all).
• --depth-fade: dim far-side lines by up to this fraction (default 0.4).
• --export sunjson: also write exactly the drawn bundle as SunJSON beside the PNG (needs --timestamp). See Export to JHelioviewer.
• Camera flags are the same as the squashing-factor render.