# Questions tagged [spherical-geometry]

Spherical geometry is the geometry of the two-dimensional surface of a sphere.

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### Compute the length of a line of latitude between two longitudes assuming a spherical Earth

I am trying to compute the length between two longitude lines along a latitude line on a sphere. I can find the great circle distance (haversine formula), and the straight line distance (cosine), but ...
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### Angle between 2 arc of circle on a sphere [closed]

I have 4 points with (lat, long) coordinates. Lets say A = (lat_A, lon_A) B = (lat_B, lon_B) C = (lat_C, lon_C) D = (lat_D, lon_D) A and B make the first arc, C and D the second. I would like to ...
29 views

### Calculating intersection of a line segment with a circle on Earth's surface from latitude and longitude coordinates

I'm working on a problem where I need to determine if a line segment between two geographical points on the Earth's surface, intersects with a circle on the Earth's surface, defined by a central point ...
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### Determine whether two circles drawn around two lat/long points with two radii intersect

I am trying to find a way to check whether two circles drawn around two lat/long points intersect. For example, x1 = (lat1 in degree, long1 in degree) x2 = (lat2 in degree, long2 in degree) c1 = ...
1 vote
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### Transformation from Lambert azimuthal equal-area to WGS84 uncovers polar region

I'm having an issue where a transformation from a projected coordinate system (Lambert azimuthal equal-area) to WGS84 changes the shape of my polygon near the polar region. The real data creates a ...
1 vote
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### How to illustrate geodesic line reflecting bearing between two points + third projected point

I'm using Spatialite + ST_Project to extrapolate a line with an implied bearing between two points to some distance beyond those two points. Here's an example sql snippet: SELECT AsGeoJSON(ST_Project( ...
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1 vote
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### Derive a center point and radius from a set of GPS coordinates and bearings

I have a problem similar to Triangulation: Estimate a location using lat/long coordinates and bearings. I have a series of GPS coordinates and bearings for each coordinate as well as accuracy for each ...
1 vote
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### Measuring distance using QGIS

Normally if you measure the distance of line and polygon in Cartesian is smaller compare to Ellipsoidal in QGIS. However, when I am measuring the distance Cartesian system gives greater value compare ...
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1 vote
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### Interchangeability between ellipsoidal CRS, and spherical CRS with the authalic radius of the same ellipsoid?

The Uber H3 documentation states: The coordinate reference system (CRS) is spherical coordinates with the WGS84/EPSG:4326 authalic radius. It is common to use WGS84 CRS data with the H3 library. To ...
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### How to obtain the minimal covering of a circle with H3 hexagons?

Given an EPSG:4326 lon,lat coordinate pair, and a radius r in meters, I want to find the smallest set of H3 hexagons at resolution res that completely covers the circle centered at lon,lat with radius ...
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### How get distance in degrees to calculate buffers in AWS Athena?

Athena only allows to calculate the distance of the buffer in decimal degrees but this value varies with respect to the latitude in the globe, tate to obtain a distance according to the following ...
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### Different area values in aggregate function

In QGIS 3.22.8 the aggregate function used in text field shows planar area values instead of spherical. It happens in both the Print Layout and the Report. How can I get the spherical values of the ...
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### Determining if a GeoTIFF's projection is in spherical or cartesian coordinates

I have received GeoTIFF that may be projected into a UTM or cartesian coordinate system or may be in a spherical (lat/lon) coordinate system. Is there a reliable way to automatically determine which ...
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### Derivation of Lat/lon given radial and distance [duplicate]

I'm looking for a derivation of the following aviation formula. I found this on one or two other sites as well but no explanation. http://www.edwilliams.org/avform147.htm#LL I took a stab at this ...
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### Adding relative spherical coordinates to absolute Lat/Lon/Alt coordinates

I have an absolute position of an observer given in Lat/Lon/Alt (on earth, ellipsoid). The observer observes an object and measures azimuth (angle), elevation (angle) and range (NM) to this object ...
174 views

### Are latitudes -90 and +90 both valid in WGS84?

Geometrically, I understand that a sphere can be addressed in latitude and longitude on the ranges [-90, +90] and (-inf, +inf) respectively. However, I am working on the specification for plus codes, ...
1 vote
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### What are practical means for drawing an approximately rectangular geofenced area that includes the North Pole?

A naïve geofence approach is to take a "rectangle" that has a min/max latitude and a min/max longitude. This approach fails at the meridian, but that can be fixed by inverting some logic ...
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### Calculate the distance between two points on a sphere (earth) going through the earth?

I can see the formula and name of the term for the distance between any two points on a sphere when going around the surface of the sphere is the great-circle distance, or orthodromic distance. What ...
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### Change of latitude and longitude when rotating around an Euler pole

Suppose we have a point P on the surface of the Earth characterized by its latitude and longitude. There is an Euler pole given together with an angle of rotation around the axis associated with this ...
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### Convert from spherical angles to longitude and latitude

I have some images extracted from a radar from Austria and a formula for the projections (the exercice says The projection formulas map pixel locations to geographical coordinates), that transforms ...
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### What's the name of the area between two geographic coordinates?

Is there a name for the shape of the area defined by two sets of geographic coordinates, for example by a northwestern and southeastern corner? In other words, the shape bounded by two degrees of ...
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### What is the area of my shapes?

I created overlapping geometries and I would like to know the area of the intersection. import geopandas as gpd from shapely.geometry import Polygon polys1 = gpd.GeoSeries([Polygon([(0,0), (0,1), (1,...
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### Calculating third coordinate on earth given two points and their distances to third point EPSG:4326 (WGS84)

I am trying to find the latitude and longitude of a 3rd point on a map with EPSG:4326 (WGS84) projection. I know the coordinates of two other points and the distance in meters to the 3rd point. ...
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### Calculate where a geodesic line crosses a meridian

Given a geodesic line between two points with known coordinates on a sphere, is there an easy way to calculate or approximate where this line crosses a specific meridian? I want to calculate where ...
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### Generate arc from projection coordinates

I have a mind to generate arc from given parameters: start point coordinates arcDistance arcBearing arcOrigin coordinates. My concept is, calculate the end point of arc (function geo.sphere....
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### Converting the local coordinates to GPS (lat, long)

I am having the XYZ points in some local coordinate frame. Each point I have, can also be represented as the distance from the origin and the azimuth angle it makes with one of the horizontal axis. I ...
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### Problem with gdal_translate when converting a GeoTiff with spherical datum to a netCDF

I have a raster file with LCC projection and spherical datum. It actually has the following proj4 parameters: +proj=lcc +lat_1=45 +lat_2=22 +lat_0=38.7 +lon_0=20 +x_0=0 +y_0=0 +a=6370000 +b=6370000 +...
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### Area between two longitudes? [closed]

I am trying to compute the area between two longitudes (using the angle between them) but am having a hard time. I can do that more easily between latitudes but longitude reveals to be tricky. Anyone ...
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### Checking small distance calculation in UTM zone 31 ETRS89

I'm afraid I've a very basic question about interpreting UTM grid values: Are the grid references in metres? I have data from the Spanish catastral map labelled as UTM Zone 31 ETRS89, and want to ...
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### Find coordinates of extended line segment intersects with given longitude

I have a line between C1 and C2; My Coordinates are; C1: 36.454N - 21.785E C2: 41.725N - 38.475E I want to find C3 latitude value based on given longitude when I extend my C1-C2 line segment. IE ...
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### Oblate ellipsoids and latitude

I've been reading Wikipedia and am having a bit of trouble. https://en.wikipedia.org/wiki/Latitude Geodetic latitude would clearly change if the Earth were squashed vertically. But would places ...
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### Latitude of Earth reference ellipsoid [closed]

I am trying to create a graphic demonstrating the difference between an idealized perfect sphere and the Earth's reference ellipsoid. (I know this is also an approximation, but nevertheless.) To this ...
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### Creating buffer circle x kilometers from point using Python?

I am wanting to create a circle with an inputted radius around a point of predetermined latitude and longitude. I've been trying to use the formula found in this post which uses an algorithm ...
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### How to generate a Global Voronoi diagram?

Using arcMap, QGIS and similar software it is easy to create a non-global Voronoi diagram. The resulting shapefile polygons however are showing weird behavior when crossing the -180 meridian or the ...
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### How to calculate intersection of two arcs? [closed]

Given two arcs (defined by start and end points with latitude and longitude) how to check if there is intersection (cross point) and if there is -- how to calculate it? Calculate "manually" -- i.e. I ...
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### Distance of a Lat long from a Polyline

I am currently looking for a solution where i need to find if a lat long is on the route or not. I cannot use Google Maps Geometry IsLocationOnEdge() or ContainsLocation() api's as i am working on a ...
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### Calculate vx, vy and vz components from Lat,Lon, height and Time

Referring to the following post Calculate velocity x and y components from Lat,Lon and Time Given the two points with Latitude, Longitude, Height and time P0 = (Lat0,Lon0, h0, time0) and P1 = (...
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### Using Spherical Standard Deviation to identify ledges on steep cliffs? [closed]

I have been implementing the approach highlighted here: Finding regions or zones in raster DEM of similar slope or aspect values in ArcGIS for Desktop? to calculate firstly the "spherical variance" ...
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### plotting a circle in a spreadsheet

I can't get my head around plotting a circle on a big sphere (Planet Earth). I have a column that has 180 rows - 1 for each degree. The next row is each degree converted to radians. Easy so far. A1 ...
1 vote
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### Map camera image onto sphere

How would I determine what the red point (phi', theta') is for a camera oriented at a known (phi, theta) is from a given image? The point of this is to determine what (dphi, dtheta) is so that I can ...
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### Converting spherical coordinates to geographic coordinates in complicated netcdf file [closed]

I am very new with netcdf file. And currently have to extract the data from such netcdf which looks like below: 8 variables (excluding dimension variables): double time_bnds[bnds,time] ...
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### Find lat/long of Point 2 a given distance from Point 1

I'm creating a program using the Bing Maps API where the user inputs a bounding box with lat/long, and the program extracts a number of static images at zoom level 15 to later be mosaicked together. ...
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### How can I build CRS string in Trasverse Mercator to increase distance measurement accuracy?

I've searched a lot in the forum finding several answers to part of my problem. In brief I need to make some computation keeping in account the distance from every point along different angles until a ...
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I need to know what is the unit of radius (e.g. miles, kilometers etc) in following question: How to place markers on the outline of a circle in google maps?
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### Calculate velocity x and y components from Lat,Lon and Time

I'm trying to calculate velocity components in the X and Y direction given two points: P0 = (Lat0,Lon0,Time0) and P1 = (Lat1,Lon1,Time1) The points are pretty close together so the components ...
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### Understanding the s2 library (geometry on the sphere, cells and Hilbert curve) for finding points nearby

I am having trouble understanding how the S2 library works so things in this question may make no sense, but I have a goal I would like to accomplish. Lets say I have many lat/lng point I want to ...
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After plotting our point-to-point radio sites and links in QGIS using Ordnance Survey map layers I'm wondering whether I can extract some information for this. For each link I would like to ...
1 vote
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### Why computing the distance between two ellipsoidal coordinates needs to be iterative?

I have found internal Android code that calculates distance between two spheroidal coordinates. It is complex and it is iterative. Why? Can't this calculation be done in "single shot"? The Java code ...
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