Geodesy Tools

Browse all available geodesy tools.

Available tools

2DRMS Horizontal Accuracy Calculator Compute 2DRMS from supplied horizontal standard deviations, exposing its approximately 98.17% radial coverage only in the unbiased isotropic Gaussian case; not universally 95% accuracy.
Albers Equal-Area Conic Projection Constants Calculator Compute Albers equal-area conic n and C from ellipsoidal parallel m/q weights, including the tangent limit and explicit zero-n degeneracy; no complete Albers coordinate transform.
Authalic Latitude Equal-Area Converter Compute equal-area authalic latitude using ellipsoidal q(phi)/q(pole), with stable spherical and polar limits; no Earth gravity model inferred.
Authalic Radius Calculator Compute the equal-surface-area sphere radius of supplied oblate ellipsoid axes, with a continuous spherical limit; not mean arithmetic or volumetric radius.
Azimuthal Equidistant Center-Distance Checker Project a point with spherical azimuthal-equidistant equations and compare its planar radius with center-to-point great-circle distance; antipodes rejected, does not preserve distances between arbitrary noncentral points.
Bowditch Traverse Adjustment Calculator Apply the local Bowditch/compass rule, distributing closure proportional to leg lengths; returns component corrections and adjusted coordinates, not least-squares network accuracy.
Bowring Geocentric to Geodetic Coordinate Converter Convert geocentric latitude plus radius using Bowring initialization and bounded refinement; returns geodetic latitude/height and ECEF residual, excluding deep-interior ambiguous normals.
Cassini-Soldner Transverse Scale Along Meridian Checker Check spherical Cassini-Soldner meridian differential scale from analytical forward-map derivatives, unity on the central meridian; restricted to +/-30 degrees longitude and |latitude|<=85, not ellipsoidal Cassini accuracy.
Circular Error Probable (CEP50) Calculator Compute radial 50th-percentile error for an unbiased independent isotropic two-axis Gaussian; not an anisotropic/bias-bearing CEP approximation or measured positioning guarantee.
Combined Curvature and Refraction Correction Calculator Evaluate the explicitly named historical combined curvature/refraction approximation 0.0675*dKm^2 meters; fixed conventional coefficient, not measured refraction or an exact universal Earth model.
Dilution of Precision DOP Geometric Factor Classifier Classify a positive supplied DOP under explicit heuristic cutoffs 1,2,5,10,20; labels are educational, not receiver accuracy, integrity or survey acceptance standards.
Double Meridian Distance Traverse Area Calculator Compute signed traverse area by double-meridian distances from explicitly closed local north/east leg increments; positive is counterclockwise in east/north coordinates, no geodetic area or hidden closure correction.
Earth Curvature Drop Calculator Compute exact spherical surface drop below a tangent plane at an explicit horizontal offset, not along-surface arc distance; no refraction and no ellipsoid/terrain prediction.
ECEF to Geodetic Coordinate Converter Convert exterior/near-surface ECEF meters to geodetic latitude, longitude and ellipsoidal height with bounded iteration and explicit round-trip residual; excludes deep-interior ambiguous normals.
Ellipsoid Flattening Calculator Compute oblate ellipsoid geometric flattening (a-b)/a from matching meter axes; supports spheres and b>=0.9a, not dynamical flattening.
Ellipsoidal Height Calculator Apply the physical height relation h=H+N with explicit matching vertical datum/tide-system geoid undulation N; no geoid lookup or automatic vertical-datum transformation.
ENU Local Tangent Plane Component Converter Rotate an ECEF displacement vector into ellipsoidal East/North/Up at an explicit origin latitude/longitude; input is a delta, not an absolute position or a datum transformation.
Gauss Conformal Latitude Calculator Compute Gauss conformal latitude from ellipsoidal isometric latitude; finite nonpolar input only, no planar projection or datum conversion.
Gaussian Radius of Curvature Calculator Compute Gaussian mean curvature radius sqrt(M*N) from ellipsoid geometry at latitude, deriving both directional curvature radii rather than averaging caller numbers.
Geodetic to ECEF Coordinate Converter Convert explicit ellipsoidal geodetic coordinates to right-handed ECEF meters; latitude/longitude degrees, ellipsoidal height not orthometric height, no datum shift.
Geodetic to Geocentric Latitude Converter Convert geodetic to geocentric latitude on the ellipsoid surface (height zero), not arbitrary elevated ECEF position; oblate f<=0.02.
Geoid Separation Gradient per km Estimator Estimate directional geoid-undulation gradient from same-model/same-epoch endpoint values and explicit positive ground separation; not a global geoid model or automatic vertical deflection.
GPS Week Rollover Resolver Resolve a modulo GPS broadcast week only when a unique nonnegative full week lies within half a rollover of a caller reference; ties/out-of-window eras reject, with no current-clock or UTC inference.
Greenwich Sidereal Time Approximation Hours Calculator Compute the historical IAU-1982-style approximate Greenwich mean sidereal time from an explicit UT1 Julian date within 1900-2100; no apparent sidereal time, nutation or automatic UTC-to-UT1 correction.
GRS80 Flattening Parameter Lookup Return the published rounded GRS80 geometric flattening, distinct from WGS84 and dynamical J2; not a datum realization transform.
Helmert Scale Correction Calculator Apply the signed Helmert scale convention k=1+ppm*1e-6 and expose its coordinate correction separately; not a full Helmert transform.
Helmert Transform Coordinate Rotation Applier Apply a static seven-parameter small-angle 3D Helmert in explicit position-vector or coordinate-frame convention; rotations arcseconds, scale ppm, no guessed datum/epoch or kinematic rates.
Horizon Dip Angle from Eye Height Calculator Compute exact geometric spherical horizon dip from eye height and radius, excluding atmospheric refraction; distinct from refracted nautical empirical dip corrections.
International Gravity Formula 1967 Value Calculator Evaluate the historical International Gravity Formula 1967 at sea level in m/s^2, not GRS80/WGS84 gravity or an observed anomaly.
Isometric Latitude Computation Calculator Compute dimensionless ellipsoidal isometric latitude as asinh(tan(phi))-e*atanh(e*sin(phi)); poles are divergent and rejected.
Isostatic Compensation Depth Airy Heiskanen Estimate Calculator Estimate an Airy-Heiskanen local root from crust/mantle density contrast and positive relief, returning depth below the reference datum; ignores flexure, lateral density changes and real crustal structure.
Julian Date from Calendar Date Standard Converter Convert proleptic Gregorian civil date plus same-scale uniform-day seconds to fractional Julian date (noon origin); time scale is caller-defined, no UTC leap-second instant or calendar-cutover inference.
Lambert Conformal Conic Constant n Solver from Two Parallels Compute Lambert conformal-conic cone constant from ellipsoidal m and isometric latitude at two parallels, using the tangent limit for identical parallels and marking degenerate n=0; not a complete LCC map.
Laplace Equation Azimuth Correction from Deflections Calculator Compute the Laplace azimuth difference astronomical-minus-geodetic = eta*tan(geodetic latitude), using east-positive eta; excludes poles and higher-order deflection effects.
Leap Second Count Since 1972 Counter Count actual published positive leap seconds since the 1972 ten-second TAI-UTC baseline using a pinned IERS table; rejects dates before 1972 or beyond its stated expiration.
Leveling Loop Closure mm per km Grade Checker Check absolute leveling loop closure against a caller-established coefficient*sqrt(distanceKm) criterion; reports the supplied grade definition, not an invented jurisdictional grade or survey certification.
Linear Eccentricity c from a and e Calculator Compute ellipsoid focal linear eccentricity c=a*e in meters from a dimensionless first eccentricity, requiring 0<=e<1.
Mercator Northing Meridional Part Table Row Calculator Compute ellipsoidal Mercator northing relative to the equator and dimensionless-radian meridional parts expressed as arcminutes; excludes poles, false northing and scale factors.
Meridian Arc Length Degree Interval Calculator Compute signed ellipsoidal meridian distance between explicit geodetic latitudes by bounded numerical quadrature; northward positive, longitude irrelevant.
Meridian Arc Length Inverse Problem Solver Invert signed equator-referenced meridian distance within the polar quadrants using at most 64 bisections and explicit residual/convergence, not an arbitrary along-path inverse.
Meridian Radius of Curvature M Calculator Compute the meridional M radius of curvature of an explicit oblate/spherical ellipsoid in meters, not a generic global Earth radius.
Modified Julian Date MJD Converter Convert a same-time-scale Julian date to modified Julian date with the exact epoch offset 2400000.5 days; does not convert UTC, UT1 or TT.
Mollweide Projection Area Conservation Spot Checker Spot-check spherical Mollweide equal-area behavior using finite-difference Jacobian of the actual forward map, not a hardcoded area identity; |latitude|<=85, local differential check only.
Molodensky Datum Shift Simplified A-B-Delta Converter Apply standard first-order Molodensky shifts using caller-established source ellipsoid, three translations and target-minus-source da/df; no built-in datum parameters, rotations or global accuracy guarantee.
Normal Gravity at Sea Level Equator 978032 mGal Lookup Return rounded GRS80 equatorial sea-level normal gravity; the milestone title 978032 mGal is approximate, not an exact universal observed gravity.
Orthometric Height H from h minus N Calculator Apply the physical height relation h=H+N with explicit matching vertical datum/tide-system geoid undulation N; no geoid lookup or automatic vertical-datum transformation.
Parallel Arc Length One Degree Longitude Calculator Compute one-degree parallel arc from local prime-vertical radius and geodetic latitude, zero at poles; not a fixed spherical longitude conversion.
Polar Motion Displacement Calculator Compute first-order Cartesian polar-motion displacement for explicitly stated rotation/sign convention from supplied xp/yp; omits s-prime, UT1, precession/nutation and full IERS frame transformation.
Prime Vertical Radius of Curvature N Calculator Compute the prime-vertical N radius of curvature of an explicit oblate/spherical ellipsoid in meters, not a generic global Earth radius.
Reciprocal Azimuth Difference Blunder Flag Checker Flag supplied local forward/back azimuth reciprocity discrepancies against an explicit tolerance, preserving signed angular wrap; distant geodesic endpoints need not have exact reciprocal bearings.
Rectifying Latitude Meridian Arc Fraction Converter Compute rectifying latitude from signed equator-to-latitude meridian distance and rectifying radius, using bounded numerical quadrature.
Rectifying Radius Calculator Compute rectifying radius as meridian-quadrant length divided by pi/2 using bounded 1024-panel Simpson integration; b>=0.98a, not arithmetic mean radius.
Reduced Parametric Latitude Converter Convert geodetic latitude to reduced/parametric latitude atan2((b/a)sin(phi),cos(phi)), preserving poles and sign on oblate/spherical ellipsoids.
Robinson Projection Calculator (Linear Interpolation) Interpolate the published Robinson 5-degree coefficient table linearly and project spherical coordinates; explicitly not conformal/equal-area or identical to PROJ cubic interpolation between knots.
Satellite Elevation Angle from Range Geometry Simplified Calculator Compute spherical station satellite elevation and slant range from geocentric radii and central separation, retaining below-horizon elevations; no orbital propagation or atmospheric refraction.
Second Eccentricity Squared Calculator Compute second geometric eccentricity squared (a^2-b^2)/b^2 for an oblate/spherical ellipsoid; do not confuse e-prime squared with e squared.
Seconds of Week from Day of Week Converter Convert zero-based GPS day-of-week (Sunday=0) plus seconds in a uniform 86400-second GPS day to seconds-of-week; UTC leap-second days are not interpreted.
Somigliana Normal Gravity Calculator Evaluate Somigliana normal gravity from an explicit ellipsoid and matching equatorial/polar normal-gravity constants in m/s^2; not observed gravity, altitude correction or a mixed-datum model.
State Plane Combined Factor Ground-to-Grid Calculator Apply a caller-established State Plane point scale times approximate R/(R+h) elevation reduction to ground length; requires compatible ellipsoidal height/radius, not automatic State Plane/datum lookup.
Stereographic Polar Aspect Scale True-at-Pole Checker Compute ellipsoidal polar-stereographic point scale normalized to an explicit pole scale, with analytic pole limit and same-hemisphere input; no polar coordinate inverse or geoid model.
Terrain Correction Simple Hammer Zone A Estimator Compute a flat-topped Hammer-style annular-sector terrain correction magnitude for supplied inner/outer radius, signed relief and density; no DEM sampling, fixed zone-A dimensions or complete terrain reduction.
Third Flattening Calculator Compute third flattening n=(a-b)/(a+b) from matching oblate/spherical meter axes with b>=0.9a.
Tidal Gravity Correction Solid Earth Tide Estimate Calculator Estimate degree-two solid-Earth tidal gravity from supplied external-body GM/distances/zeniths and gravimetric factor 1+h2-1.5k2; downward-positive gravity and opposite removal correction, not full IERS tides or ephemerides.
Transit Rule Alternative Adjustment Distributor Apply the local transit rule, distributing coordinate closure proportional to absolute component increments; returns component corrections and adjusted coordinates, not least-squares network accuracy.
Traverse Misclosure Lat Departure Closure Calculator Compute local traverse latitude/northing and departure/easting increments with azimuth clockwise from north, plus signed loop misclosure and perimeter; no geodesic propagation or automatic adjustment.
Traverse Precision Ratio 1-in-N Formatter Format measured traverse perimeter-to-misclosure precision ratio with explicit significant digits; zero misclosure is exact closure, not infinite certified survey accuracy.
Triangulation Triangle Closure Error Distributor Distribute triangle angle-sum closure by inverse precision weights toward 180 degrees plus supplied spherical excess; adjustment arithmetic does not establish measured-angle validity or a complete network solution.
Trigonometric Heighting Difference Calculator with Earth Curvature Estimate trigonometric target-minus-station height from slant geometry, instrument/target heights and positive curvature/refraction term (1-k)D^2/(2R); local small-angle model, not full geodetic leveling.
UT1–UTC Interpolator and Delta T Calculator Interpolate supplied DUT1 observations through continuous UT1-TAI, then distinguish UT1-UTC from DeltaT=TT-UT1 using the pinned IERS leap table; no invented Earth-rotation observations or extrapolation.
UTM Grid Convergence Angle gamma Calculator Estimate ellipsoidal TM grid convergence through cubic longitude terms within +/-3 degrees of the central meridian; positive east-of-central in the northern hemisphere, not a full projection solver.
UTM Point Scale Factor k0 Gamma Series Calculator Estimate ellipsoidal transverse-Mercator point scale with a fourth-order longitude series, limited to +/-3 degrees from the central meridian and |latitude|<=84; not a full global UTM engine.
UTM Scale Factor at Central Meridian 0.9996 Lookup Return the defining UTM central-meridian scale k0=0.9996 for either hemisphere; no zone selection, point scale, convergence or coordinate projection.
Vertical Gradient of Gravity microGal per metre Calculator Compute a measured signed upward vertical gravity gradient from two same-convention observations and positive height separation; no imposed free-air gradient or terrain correction.
Vincenty Direct Geodesic Calculator Solve Vincenty direct geodesics on supplied oblate/spherical ellipsoids, bounded to 200 iterations and half-equatorial circumference; report forward end bearing and explicit nonconvergence.
Vincenty Inverse Geodesic Calculator Solve Vincenty inverse distance and forward endpoint bearings with a 200-iteration cap; near-antipodal failure returns null distances, never a fabricated spherical fallback.
WGS84 Semi Major Lookup Return the WGS84 ellipsoid semi-major axis in metres for the requested realisation.
Zenith Angle from Altitude Complement Calculator Convert signed horizon altitude in [-90,90] degrees to zenith angle [0,180] degrees; same apparent/geometric convention must be retained.