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

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Is there a world projection that looks like a 3D globe?

I would like to try and show data such that it appears as if it was on google earth. For example, in this case, the view of the earth is circular-like and the data shown curves around. Are there any ...
3
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2answers
996 views

How do I find the points of intersection between a small circle and a great circle?

I only actually need to intersect a great circle arc i.e. the shortest path between two points, with a given small circle. I found this tutorial for intersecting two great circle arcs, but ...
3
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1answer
194 views

Proof of part of haversine formula?

I'm trying to study how to find the distance between two points if their latitudes and longitudes are given. I have a question about the proof of part of the haversine formula given at Math Forum. ...
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3answers
1k views

Formula for coordinates (lat, lon), azimuth and distance.

I would like to know how to find a set of coordinates on a small circle some distance from another point. For example, lets say A = (39.73, -104.98) #Denver B = (39.83, -106.06) #point ...
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2answers
1k views

Finding the minimum and maximum distance between an observer and a lat/lon bounding box

I have three points in geographic coordinates (latitude, longitude, altitude). One of the points represents an observer, above the Earth. The other two points define a bounding box. I'd like a ...
3
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1answer
114 views

After how much distance does the x,y coordinate system become noticeably distorted?

I'm working with maritime sensors that give information of moving objects it detects, in azimuth, range and elevation, and we convert it to x,y coordinates for our application to be able to process ...
3
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1answer
111 views

Direct Geodesic with Point 2 Azimuth

I am trying to find a way to calculate the direct problem on the WGS-84 ellipsoid but instead of using the initial Azimuth (e.g. lat1, lon1, distance, fwd azi), I want to compute it with the reverse ...
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2answers
792 views

Variation of algorithms to find point from another point with bearing and distance

There are several algorithms to calculate distance between two latitude/longitude points. Haversine Hubeny Lambert-Andoyer Vincenty's formulae for inverse problem But there are not so many ...
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1answer
2k views

How to calculate midpoint given north/south latitude and east/west longitude?

First, sorry if this questions sound very simple. I am very new to GIS. Given four values of north/south latitude, east/west longitude how to calculate the center point that is correct for all cases ...
3
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1answer
136 views

Algorithm to draw a perpendicular line on Google earth (KML)

I have two points say A (lat,lon ) and B(lat,lon) and I want to draw a perpendicular bisector line to AB such that any point (C) on the perpendicular line satisfies AC=BC. All I want is a function ...
3
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1answer
154 views

Is there a straightforward way to tweak LatLon on a sphere to represent true LatLon?

I have no experience in mapping, so please excuse me if this sounds foolish. I'm trying to use Microsoft MapPoint (2004) software to geocode a number of addresses in Excel. However, my version of ...
3
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1answer
909 views

XY to Line tool crashing

The problem I'm encountering is simple. I have a shape file of points (about 8 million). They have three XY pairs that I am attempting to create XY lines from for purposes of measuring distance. ...
3
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0answers
20 views

How to calculate the distance (difference?) between two reigons

I am building a machine learning system which predicts the location of tweets as a bounding box (using the google maps API among other things). Since the twitter API also supplies a bounding box, I am ...
3
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0answers
67 views

Given distances from two locations how to accurately find geographic coordinates [duplicate]

I am working on a research problem which requires me to calculate a geographic location accurately (with error distance of few meters), given distances from two geographic locations. For instance: ...
3
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0answers
142 views

Converting LIDAR based measurement to UTM coordinate?

I have lidar based measurement with azimuth elevation and range, I would like to convert this data to UTM coordinate. I know the position of the lidar in UTM coordinate system, so I developed the ...
2
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3answers
3k views

Local Coordinate to Geocentric

The ultimate question, I need a transformation matrix to take a point in local space representing a roughly 500m x 500m place in New Mexico centered at -108.619987456 long 36.234600064 lat. The final ...
2
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3answers
2k views

How to compute distance between 4500 points fast?

I am working on a location problem with 150 customers (points) and 30 facilities (points). I have determined the location of any customer and facility by google earth and then saved them in a KMZ ...
2
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2answers
510 views

How to find the destination point given a start point, distance and bearing?

If I have a starting point as well as distance and a bearing to the destination point, how can I find the coordinates of the destination point using PostGIS? I'm looking for a PostGIS equivalent to ...
2
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1answer
5k views

Calculate longitude length in miles

Suppose I have geographic coordinates of "Saratoga, California, USA" as Latitude: 37°15.8298′ N Longitude: 122° 1.3806′ W I know from here that in case of latitude 1° ≈ 69 miles and that ...
2
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1answer
2k views

Transforming regular lat/lon to rotated lat/lon?

I am currently working with climate data projected in a rotated lat/lon grid and came across this excellent 'cookbook' by mkadunc on how to manually transform rotated lat/lon to regular lat/lon: ...
2
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1answer
161 views

Point to Line Calculations

We are looking to take a point and compare it against the nearest point to an adjacent line. All values are in lat/long. We tried using some of the concept found on the board but found it did not ...
2
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1answer
742 views

Map projection lat, lon to pixel?

I'm trying to find the concave hull of a lat, lon pointset but when I project my points on my map it doesn't look like expected. I've tried a lineare projection and a spherical projection. My data is ...
2
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1answer
1k views

MySQL GeoSpatial function for ST_Distance_Spheroid? Metric used in return Type of GLength?

Is there a ST_Distance_Sphere, ST_Distance_Spheroid equivalent function in MySQL's GeoSpatial Support? If not, any way to emulate this? What is the metric used in return type of ...
2
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1answer
266 views

Does spherical equilateral triangle T contain point P?

I am working on a Python script to: compute the vertex coordinates of a geodesic sphere/icosahedron, project the triangles onto a sphere, then find which spherical triangle contains an arbitrary ...
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0answers
27 views

How to properly deal with rectangles being curved on geographies?

I'm using Microsoft SQL Server to store simple data for administrative boundaries of the world (lots of polygons). I store this in a geography data type column. Afterwards I query these polygons by a ...
2
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1answer
121 views

Getting coordinates at location n meters from known point to NW and SE using ArcPy?

I have a point shapefile or feature class and I want to create bounding boxes around each point. The size of the bounding box will depend on user input, for example the user might want a bounding box ...
2
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1answer
123 views

Calculating a point Lat/Lon from another Lat/Lon point angle

I need help for a solution of this problem to make an algorithm: : I have a point O center of a circle of radius r, on this circle there is two point P1 and P2. I know latitude and longitude of ...
2
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1answer
101 views

Is a point within a polygon

I need help in this question. To explain briefly -- the question is: Whether a point with coordinates lng:-80.087535 lat: 42.054246 lies over or under line with coordinates: lng: -80.267831 ... ...
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0answers
204 views

Determine PostGIS geography polygon orientation

How can you determine the orientation of a PostGIS geography polygon? I'm looking/hoping for a function that would tell me which side is the interior (left or right) as you traverse the vertices of ...
2
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1answer
146 views

Draw a line and a buffer around it onto the spheroid

I need to draw a line between two points and create a buffer around this line. The only difficulty is that I need to draw not a "cartesian" line but a line that is laying on the spheroid. I tried to ...
2
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0answers
92 views

How can I figure out whether a sphere is intersecting the Earth between a given lon/lat range?

Given a lon/lat range that represents a tile on the Earth's surface, I need a computationally efficient way to figure out if a spherical volume defined by a point (assume ECEF coordinates) and a ...
2
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0answers
200 views

Specifying a bounding rectangle using Google's S2 package for spherical geometry [duplicate]

This is my first post on GIS, I hope it is not too trivial a question. I work on a project on Google AppEngine, which is backed by a NoSQL datastore. This makes a proximity filter different from ...
2
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0answers
117 views

Find arc endpoint with bearing and radius counting with curvature of the earth?

So my problem is that I have start point [lat,long] for arch, bearing, radius and I need compute end point [lat,long] ? End point should be in 180 degrees angle from start point and I should be aware ...
2
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0answers
234 views

Centroid of the equator and a point

Suppose I already have a way to compute the centroids of different geometry types: Points (arithmetic mean of Cartesian coordinates). Linestrings (polylines) (weighted mean of segment mid-points in ...
2
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0answers
182 views

Placement of a fixed-radius circle on a sphere to maximize point containment

There are many papers on the "Circle Placement Problem" in 2D Euclidean space, but I haven't been able to find any papers discussing this problem on the sphere. The problem is: given a set of points ...
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1answer
226 views

Moving object of fixed dimension without distortion

I am trying to move a polygon object in a shapefile to a new location. I will perform an offset so that the process can be automated by shifting the object to a new geographic coordinate or moved by ...
1
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2answers
439 views

Polygon area calculation in Ruby (on Rails, rgeo, PostGIS and GEOS) in sqare meters

In a Ruby-on-Rails application, I need the area in square meters (or any other surface measure, be it ares, hectares, square kilometers, but not in pseudo surface measure like square degrees) of a ...
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2answers
58 views

Spherical law of cosine what does the 'a' represent?

I want to use the spherical law of cosine formula, θ = atan2( sin Δλ ⋅ cos φ2 , cos φ1 ⋅ sin φ2 − sin φ1 ⋅ cos φ2 ⋅ cos Δλ ), to calculate distances between coordinates, but, I cannot for the life ...
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1answer
253 views

How do I figure out the grid references (Eastings and Northings) necessary to create a circular 1 mile radius around one location?

How do I figure out the grid references necessary to create a circular 1 mile radius around one location? For instance: Grid Reference: SO 47904 87484 X (Eastings): 347904 Y (Northings): 287484 ...
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1answer
1k views

Lat Long line intersecting with circle

Can anyone help me what's the algorythm to calculate points of intersection whet is given one point p1 [lat,long] , bearing x (let say 137 degrees), arc center [lat,long] and radius? I woulde like to ...
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1answer
56 views

JTS polygon intersection calc on a geoid

I am using JTS to compute intersections between polygons with WGS84 lat/lon coordinates. I am not converting coordinates to anything 2D based, just reading in POLYGON(lat lon, lat lon) and doing ...
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2answers
883 views

Is there an average size for British postcodes?

Is there an average size for British postcodes? Or a method of determining the size for a particular British postcode? Thanks. Considering creating a related program and this would be valuable ...
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1answer
145 views

Defining a line from geographic coordinate points.

On a flat surface we can define any point on line which passes from point1 (x1,y1) to point2 (x2,y2) via simple trigonometry. How can we do that with latitude and longitude of 2 points? Imagine we ...
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2answers
980 views

OpenLayers Circle not visible

I'm trying to draw a circle with OpenLayers with a Google Maps Layer. I'm able to transform a simple marker and have it draw at the correct location, but I can't figure out the circle. I'm trying to ...
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1answer
277 views

Lambert cylindrical projection support in PostGis

Does PostGis support Lambert cylindrical projection or is there a way to add support for it? I'm probably searching the wrong terms, but google isn't bringing up anything useful. Any help is ...
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2answers
4k views

Equations to convert from global cartesian coordinates to geographic coordinates

First, I needed to convert geographic coordinates (like those received from GPS) to global cartesian coordinates. I found an earlier question (How do I calculate a xyz-position of a gps-position ...
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1answer
65 views

What is the radius of earth [duplicate]

What is the real radius of earth? Google says 6378.1 km Wiki says 6371 km And there are references for 6378.7 km I'm using maximum radius 6378.7 km in distance calculation in spherical law of ...
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1answer
610 views

Converting Lambert Conformal (x, y) of spheroid to (lon, lat) of NAD83 with proj/cs2cs?

Revised Trial: Correct? According to Andre Joost advice, I tried with "+towgs84=0,0,0", and the both two ways seem to get the same answer that mkennedy posted below. So, just to make sure, anybody ...
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1answer
153 views

How do I convert OS coordinates (X and Y) to longitude and latitude coordinates?

How do I convert OS coordinates (X and Y) - Eastings and Northings to longitude and latitude coordinates? For example X and Y below X (Eastings): 347904 Y (Northings): 287484
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2answers
626 views

Given a flight path given in latitudes and longitudes, how do I find another flight path that is parallel to the path given?

Given a flight route that is given in latitudes and longitudes, how do I find another route that is "parallel" to the route given (find a perpendicular line to each waypoint given)? I think the best ...