Supported Projections

vibeProj supports 24 coordinate projections. Each has both a NumPy/CuPy element-wise implementation and a fused NVRTC GPU kernel.

Projection table

Projection	Internal Name	EPSG Examples	Notes
Transverse Mercator / UTM	tmerc	32601–32760, 27700	6th-order Krueger series
Web Mercator	webmerc	3857	Spherical Mercator
Mercator (ellipsoidal)	merc	3395	Variant A/B
Lambert Conformal Conic	lcc	2154	1SP and 2SP
Albers Equal Area	aea	5070	Conic equal-area
Polar Stereographic	stere	3031, 3413	Variants A/B/C
Lambert Azimuthal Equal Area	laea	3035	Oblique/equatorial/polar
Oblique Stereographic	sterea	28992	Double projection via conformal sphere
Plate Carree	eqc	4087	Equidistant cylindrical
Sinusoidal	sinu	–	Pseudocylindrical equal-area
Equal Earth	eqearth	8857	Polynomial pseudocylindrical
Cylindrical Equal Area	cea	6933	EASE-Grid 2.0
Orthographic	ortho	–	Globe view
Gnomonic	gnom	–	Great circle navigation
Mollweide	moll	–	Equal-area world maps
Robinson	robin	–	Compromise world maps
Winkel Tripel	wintri	–	National Geographic standard
Natural Earth	natearth	–	Polynomial pseudocylindrical
Azimuthal Equidistant	aeqd	–	Distance-from-center
Geostationary Satellite	geos	–	Weather satellite view
Oblique Mercator (Hotine)	omerc	3375	Variants A/B
Krovak	krovak	5514	North-orientated variant
Eckert IV	eck4	–	Pseudocylindrical equal-area
Eckert VI	eck6	–	Pseudocylindrical equal-area

Using projections via EPSG codes

Most projections are resolved automatically from EPSG codes via pyproj:

from vibeproj import Transformer

# UTM Zone 31N
t = Transformer.from_crs("EPSG:4326", "EPSG:32631")

# Netherlands national grid (oblique stereographic)
t = Transformer.from_crs("EPSG:4326", "EPSG:28992")

# LAEA Europe
t = Transformer.from_crs("EPSG:4326", "EPSG:3035")

Using projections without EPSG codes

Some projections (orthographic, gnomonic, etc.) don’t have standard EPSG codes. Use them via the pipeline API directly:

from vibeproj.crs import ProjectionParams
from vibeproj.ellipsoid import WGS84
from vibeproj.pipeline import TransformPipeline

# Orthographic centered on Paris
params = ProjectionParams(
    projection_name="ortho",
    ellipsoid=WGS84,
    lon_0=2.35,
    lat_0=48.86,
    north_first=False,
)
src = ProjectionParams(projection_name="longlat", ellipsoid=WGS84, north_first=True)

pipe = TransformPipeline(src, params)
x, y = pipe.transform(lat_array, lon_array, np)  # or cp for GPU

Datum shifting

When the source and destination CRS use different geodetic datums or reference frames, vibeProj asks pyproj/PROJ for the coordinate-operation plan instead of guessing from ellipsoid parameters. If the selected or best supported operation contains a Helmert step, vibeProj applies a Helmert 7-parameter transformation automatically.

# Cross-datum: WGS84 -> British National Grid (OSGB36 / Airy 1830)
t = Transformer.from_crs("EPSG:4326", "EPSG:27700")
x, y = t.transform(-0.1278, 51.5074)
print(t.accuracy)  # "sub-meter"

Helmert parameters are extracted from pyproj’s EPSG database at construction time; the actual datum shift math runs on vibeProj’s own GPU kernels (or NumPy on CPU). Same-datum transforms have zero overhead. Some datum pairs, such as common WGS84/NAD83 operations, are also represented by PROJ as explicit no-op operations with meter-level expected accuracy; vibeProj keeps those no-op transforms but reports them separately from same-datum sub-millimeter transforms.

15-parameter time-dependent Helmert is also supported for sub-decimeter accuracy on modern datum pairs (e.g. ITRF to ETRS89). Pass an explicit epoch or let vibeProj resolve it from the source CRS coordinate epoch:

t = Transformer.from_crs("EPSG:4326", "EPSG:27700", epoch=2024.0)
print(t.accuracy)  # "sub-decimeter" when 15-param rates are present

SVD-compressed datum corrections

For datum pairs where Helmert alone is insufficient (e.g. NAD27 to NAD83), vibeProj includes baked SVD-compressed corrections fitted from public domain grid data (NADCON5). These are applied automatically as an additive correction after the Helmert shift, achieving sub-5cm accuracy without external grid files.

# NAD27 → NAD83 (SVD correction applied automatically)
t = Transformer.from_crs("EPSG:4267", "EPSG:4269")
x, y = t.transform(-90.0, 40.0)
print(t.accuracy)  # "sub-5cm"

Currently baked pairs:

• NAD27 to NAD83 (CONUS) — rank-10 SVD, P95 accuracy 0.15 cm vs pyproj

For datum pairs without a baked SVD correction or Helmert parameters, vibeProj emits a RuntimeWarning and falls back to projection math without a datum shift. Results may differ from pyproj by meters to hundreds of meters in these cases.

Not yet supported:

• Raw NTv2 / NADCON grid loading — vibeProj does not load external grid files at runtime. Datum pairs not covered by baked SVD corrections or Helmert fall back to no datum shift. Use pyproj or rasterio directly if you need coverage beyond the baked pairs.

Known limitations

• Equal Earth (eqearth): Uses the spherical polynomial formula on geodetic latitude rather than converting to authalic latitude first. This means absolute metre values differ from pyproj by ~15%. Roundtrip accuracy is exact (forward and inverse are self-consistent).

• Oblique Stereographic (sterea): The double-projection through a conformal sphere introduces ~130m systematic offset from pyproj’s more rigorous method in the forward direction. The inverse conformal sphere conversion has a known accuracy limitation (~0.2 degrees). Roundtrip accuracy is sub-millimetre.

• Geostationary (geos): The inverse has limited accuracy for off-nadir points due to a simplified geocentric latitude conversion.

• Winkel Tripel (wintri): The inverse uses Newton iteration and converges to ~0.005 degrees rather than machine precision.