ephemvis

Themeable SVG rendering for astrological chart data — the display layer that pairs with openephem (the calculation core). ephemvis turns a chart dict into a self-contained chart wheel and a triangular aspect grid.

The split is deliberate: openephem computes, ephemvis draws. The math core stays small and auditable; the visuals can be forked and restyled freely without touching (or destabilising) the calculations.

Install

pip install ephemvis            # pure renderer, zero runtime deps
pip install ephemvis[compute]   # also pulls openephem to compute charts

Use

from openephem import resolve, assemble          # needs ephemvis[compute]
from ephemvis import render_svg, render_aspect_grid_svg

chart = assemble(resolve(date=(1990, 5, 15), time=(14, 30),
                         place="New York, NY"))
open("wheel.svg", "w", encoding="utf-8").write(render_svg(chart, theme="prism"))
open("grid.svg",  "w", encoding="utf-8").write(render_aspect_grid_svg(chart, theme="prism"))

render_svg and render_aspect_grid_svg accept any dict with the openephem ChartResult shape (angles, cusps, bodies, aspects), so any engine that emits that shape can be rendered — ephemvis has no dependency on how the chart was computed.

Profections

Two ways to show profections, both from a chart dict carrying a profections block (openephem's assemble() adds one for a given age/date):

A dedicated wheel — render_profection_wheel_svg(chart, theme=…) draws the whole-sign profection wheel: twelve house wedges (ASC..12th) with the natal planets in their houses, the signs on the rim, and concentric age rings (each house lists the ages that profect there — 0,12,24… in the 1st, 1,13,25… in the 2nd, …). The profected house + sign are highlighted for the chart's age, and the age cells are a heatmap keyed to age along the theme's ramp (a thermal map of life in infrared, black-light in ultraviolet). Options:

from ephemvis import render_profection_wheel_svg
svg = render_profection_wheel_svg(chart, theme="infrared", max_age=83,
                                  title="Annual Profections", planets="classical")

max_age sets the final year (the outer ring is always completed: 83 → seven rings 0–83, 84 → eight rings 0–95). planets is "classical" (default), "all", or a list of body names. title sets the top-left heading. Each sign's outer-ring arc is tinted with its Lord of the Year (domicile-ruler) colour, with two stacked legends below (the lord colours, then the age gradient).

Pass layout="spiral" to unroll the age rings into one continuous expanding coil (birth at the centre, one 12-year turn per loop). Because profections are exactly 12-periodic, each sign holds the same angle on every turn, so the recurrence reads as aligned radial wedges. layout="annulus" (concentric rings) is the default.

An overlay on the natal wheel — render_svg also marks the profection on the ordinary chart in the theme accent: a filled band on the annual profected sign and a ring tagged TL on the Lord of the Year glyph, each with a hover tooltip. A bottom-left key names the annual lord and rising sign (Lord: Mars · Aries rising) and, when the chart carries an as-of date, tags each part of that date with the sign it profects to (June ♊ · 3rd ♐ · 2030 ♒ — month → Lord of the Month's sign, day → Lord of the Day's, year → the annual sign). Pass show_profection=False to suppress it. All whole-sign, counted from the Ascendant.

Firdaria

render_firdaria_svg(chart, theme=…) draws the Persian firdaria time-lords as a horizontal timeline (they're a temporal sequence, not a wheel): a top row of major planetary periods and a bottom row of their sub-periods, each segment coloured and glyphed by its ruling planet, with the current major/sub outlined and a marker at the current age. Needs a firdaria block (openephem's assemble(..., firdaria_as_of=)).

from ephemvis import render_firdaria_svg
svg = render_firdaria_svg(chart, theme="dark", max_age=84, title="Firdaria")

max_age is the right edge (years). A companion table is trivially built from the same firdaria block. Planet identity is carried by the glyph (nine categories can't all be maximally distinct); colour is a supporting cue.

Chart style — render_firdaria_svg(chart, style="chart") projects the sequence onto the profection wheel instead (band = major lord, glyph = sub lord; the two nodes carried through), sharing the natal core with every other chart. Add layout="spiral" for the coil. Needs a profections block alongside the firdaria one.

Zodiacal Releasing

render_zodiacal_releasing_svg(chart, theme=…) draws Valens' zodiacal releasing as a horizontal timeline of nested periods: a top row of level-1 (L1) periods and a bottom row of their level-2 (L2) sub-periods. Each band is coloured by the element of its sign (Fire/Earth/Air/Water — four categories separate cleanly for colour-vision deficiency) and carries the sign's glyph as the primary identifier. Peak periods (angular from the Lot of Fortune) get an ink accent bar; a Loosing-of-the-Bond jump is marked where it occurs; the current L1 period is outlined with a marker at the current age. Needs a zodiacal_releasing block (openephem's assemble(..., releasing_as_of=)).

from ephemvis import render_zodiacal_releasing_svg
svg = render_zodiacal_releasing_svg(chart, theme="dark", max_age=84,
                                    title="Zodiacal Releasing")

max_age is the right edge (years). The Lot released (Fortune by default, or any of the seven Hermetic Lots) and the active L1→L4 path are named in the subtitle; a companion table is trivially built from the same block.

Chart style — render_zodiacal_releasing_svg(chart, style="chart") projects releasing onto the profection wheel, each cell coloured by its L1 sign's element and glyphed by its L2 sign (the angularity / peak / loosing-of-the-bond markers stay on the timeline). Add layout="spiral" for the coil. Needs a profections block alongside the zodiacal_releasing one.

Decennials

render_decennials_svg(chart, theme=…) draws Valens' decennial time-lords as a horizontal timeline: a top row of the general decennial periods (each a fixed 10 years 9 months) and a bottom row of their planetary sub-periods (unequal — each planet's minor years as months), coloured and glyphed by ruling planet, with the current general/sub lord outlined and a marker at the current age. Needs a decennials block (openephem's assemble(..., decennials_as_of=)).

from ephemvis import render_decennials_svg
svg = render_decennials_svg(chart, theme="dark", max_age=76, title="Decennials")

max_age is the right edge (years; a full cycle is ~75¼). The starting planet is named in the subtitle; a companion table is trivially built from the same block. Planet identity is carried by the glyph; colour is a supporting cue.

Chart style — render_decennials_svg(chart, style="chart") rolls the decennial Gantt onto the profection wheel (band = major lord, glyph = sub lord, radial ticks at the real sub-period boundaries, or sub_style="gradient" for sub-lord colour slices). Add layout="spiral" for the coil. Needs a profections block alongside the decennials one.

Jyotiṣa (Vedic) charts

render_vedic_square_svg(chart, style=…) draws the classical rāśi square in three regional styles — "south" (South Indian fixed-sign grid), "north" (North Indian fixed-house diamond), and "east" (East Indian / Bengali fixed-house). Grahas are placed by their sidereal rāśi (Rāhu/Ketu included), the Lagna is marked, and each house scales its contents so a dense stellium stays inside its cell. Needs a sidereal chart (assemble(zodiac="sidereal")); the same function renders any vārga (divisional) chart when the chart carries a varga block (openephem's varga_chart()).

from ephemvis import render_vedic_square_svg
svg = render_vedic_square_svg(chart, style="south", theme="meadow", title="Rāśi")

render_vimshottari_svg(chart, style=…, layout=…) draws the Vimśottarī daśā — either a horizontal timeline (Mahādaśā over Antardaśā, the balance at birth, an as-of marker) or, with style="chart", projected onto the shared wheel core (band = Mahādaśā, glyph = Antardaśā) as concentric rings (layout="annulus") or an expanding coil (layout="spiral"). The seven classical lords share the firdaria/decennials theme colours; Rāhu/Ketu carry their own. Needs a vimshottari block (openephem ≥ 0.2.0's assemble(..., vimshottari_as_of=)).

from ephemvis import render_vimshottari_svg
svg = render_vimshottari_svg(chart, style="chart", layout="spiral", theme="meadow")

Bi-wheel & synastry

render_biwheel_svg(inner, outer, …) draws a double wheel — two charts on one wheel, for comparing any pair: natal + transit, two transits, synastry (compatibility), natal + solar/lunar return, natal + progressed. The inner chart (the radix) owns the zodiac ring, the house cusps and the orientation; the outer chart's planets are placed against that same ring on their own band. Between the two planet bands sits a shared divider ring — every planet's short true-position tick points to it — and the bands sit symmetric about it. Both rings carry the full readout (glyph · degree · sign · minute) in the same order. The outer chart may be an untimed transit (no houses of its own); only the inner chart needs a house framework.

Three aspect layers cross the hub, each switchable: cross-aspects (inner × outer, bold, on by default) plus each chart's own internal aspects (faint, off by default). Cross-aspects are computed upstream — openephem's cross_aspects() returns the list:

from openephem import resolve, assemble, cross_aspects   # needs ephemvis[compute]
from ephemvis import render_biwheel_svg, render_synastry_grid_svg

natal   = assemble(resolve(date=(1990, 5, 15), time=(14, 30), place="New York, NY"))
transit = assemble(resolve(date=(2026, 9, 15), time=(12, 0),  place="New York, NY"))
cross   = cross_aspects(natal, transit)                  # flat 5° orb by default, adjustable

wheel = render_biwheel_svg(natal, transit, cross_aspects=cross,
                           labels=("Natal", "Transit"), theme="prism")
grid  = render_synastry_grid_svg(natal, transit, cross, labels=("Natal", "Transit"))

labels names the two charts (hover text, and a small legend when key=True); toggle the intra-chart layers with show_inner_aspects / show_outer_aspects, or the cross layer with show_cross_aspects. The renderer only draws — pass any two chart dicts and a cross-aspect list, from any engine that emits the shape.

render_synastry_grid_svg(inner, outer, cross, …) is the companion synastry grid: a rectangular matrix with the inner chart's bodies down the left and the outer chart's across the top, each cell showing the cross-aspect between its row and column, coloured by nature — two folded aspectarians, its gradient falling inward from both corners.

Themes

light, dark, auto, and eight pastel "pretty" modes with a prism-halo ring: prism, twilight, aurora, opal, seafoam, meadow, dawn, blossom. See ephemvis.PALETTES.

Embedded glyphs

Every SVG embeds its astrology glyphs and numerals as @font-face data URIs, so a chart renders pixel-identical on any device — no dependence on whatever symbol font the viewer happens to have (which was the source of the classic "℞ looks like a serif here, a box there" and glyph-overlap problems). The glyphs are a curated subset of the OFL Noto fonts, packaged by the sibling astroglyphs_2K toolkit and vendored into ephemvis/_fontdata.py at build time — so ephemvis still has zero runtime dependencies. The font data is under the SIL Open Font License 1.1 (see NOTICE and LICENSES/OFL.txt); the code stays MIT.

The data contract

ephemvis reads the chart dict openephem's assemble() returns:

{
  "angles": {"asc": float, "mc": float, ...} | None,   # ecliptic longitude, degrees
  "cusps":  [float] (12) | None,                        # house cusp longitudes
  "bodies": {name: {"lon": float, "retro": bool}},      # ecliptic longitude, degrees
  "aspects": [{"a": name, "b": name, "aspect": str, "orb": float}],
  "warnings": [str],
}

MIT © 2026 Elizabeth Huston, Ph.D. and Noah Christian, Ph.D.
Contact: elpisastrology@gmail.com · elpisastrology.com and noahchristian@gmail.com