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

learn more… | top users | synonyms

2
votes
1answer
57 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 ... ...
0
votes
0answers
9 views

Calculating z coordinate for longitude, latitude Google Map [duplicate]

I have a point (lon, lat) values. Is there any service to calculate Z coordinate of this point. Google service, OpenLayers service or others.
2
votes
0answers
45 views

Point sampling along a pole-wrapping coastline with PostGIS

I am working on a task that requires me to get sample points every 1000KM along coastlines, and have run into a problem with Antarctica. From what I can tell, it seems to be an issue with the use of ...
1
vote
0answers
31 views

Mapping from one plane on the other plane despite of masking regions

have a set of data given here, where in the first and second columns there are the sky coordinates (ra,dec) e.g. right ascension and declination, respectively and in the third and forth, the ...
1
vote
1answer
34 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 ...
2
votes
0answers
36 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 ...
1
vote
1answer
73 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
vote
0answers
46 views

How do I convert Lon and Lat to pixels in map using world file?

I have a tiff map file, with a tfw world file that has these parameters (lon/lat in radians): 0.00000107180145766 \\ A 0.0000000000 \\ D -0.0000000000 \\ B -0.0000009331315579 \\ E ...
1
vote
2answers
44 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 ...
1
vote
0answers
32 views

Pont to Point and Point to Line Calculations [duplicate]

We have been beeating our head against a wall trying to get point to point and point to line segment (perpindicular) to work in PHP. I posted the other day as well but did not include the code in ...
0
votes
0answers
52 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 ...
1
vote
0answers
21 views

Find coordinate of point on the boundary of a circle given a latitude/longitude and radius [duplicate]

I understand how to use the haversine formula to compute the distance between two points on the earth. However, I would like to answer a similar, albeit different question. How can I compute the ...
0
votes
0answers
24 views

Find square with latitude and longitude for given lat and lng and distance [duplicate]

I have the coordinates of some point, lets say lat and lng, I want to find the latitude and longitude of top left and bottom right corners of the square, whose sides are located k kilometers from the ...
2
votes
2answers
156 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 ...
3
votes
0answers
64 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: ...
1
vote
1answer
233 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 ...
4
votes
0answers
59 views

Compute visibility graph on sphere

I have a PostGIS table with some polygons (stored using the geography data type). They represent regions on a spherical earth. For each pair of vertices chosen from among all the polygons, I want to ...
0
votes
0answers
28 views

Quickest method for determining which postcode is 2 miles north of original postcode? [duplicate]

What is the Quickest method for determining which postcode is 2 miles north of original postcode? For instant L17. I know how to determine the distance between 2 points as below, but the above ...
0
votes
1answer
45 views

Hard to get my head around, generating average price for houses in each quadrant

I'm able to determine the average price of houses sold in a particular area (like the squares on image below) dependent upon postcode. Although I can generate the average sale price for a particular ...
1
vote
2answers
135 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 ...
1
vote
1answer
70 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
1
vote
1answer
106 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 ...
1
vote
2answers
241 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 ...
3
votes
1answer
146 views

How do I figure out the longitude and latitude coordinates necessary to create a circular 1 mile radius around one location?

How do I figure out the longitude and latitude coordinates necessary to create a circular 1 mile radius around one location? I don't mind how many coordinates that takes. For instance: Latitude = ...
1
vote
1answer
91 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 ...
1
vote
0answers
103 views

Intersection between a ray from lat, lon, alt, with pan, tilt and earth's surface

I have a problem that consists of finding the intersection point between a ray from a given lat, lon, alt, that is looking to a given pan and tilt angles and the earth's surface. I need the lat, lon ...
0
votes
0answers
53 views

recalculate latitude and longitude from a pixel in a cropped map

i want to recalculate a geographic coordinate from a pixel in a map. For this i have the size and the coordinates from the map to convert a coordinate to a pixel is use the algorithm, you find at ...
1
vote
0answers
209 views

How to approximate point to segment distance on sphere?

I would like to approximate the distance of a line segment from a reference point on the map (coordinates are gives as lat/lon). In the Cartesian coordinate system I would simply find the closest ...
9
votes
1answer
193 views

Mercator bias plot in Leaflet

I was inspired by this wikipedia image from the mercator projections page to hack around with leaflet. The idea was to interactively have your cursor move a continent and that it would be corrected ...
2
votes
3answers
558 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 ...
0
votes
0answers
197 views

Feature.geometry.transform not working

// World Geodetic System 1984 projection var WGS84 = new OpenLayers.Projection("EPSG:4326"); // WGS84 Google Mercator projection var WGS84_google_mercator = new ...
3
votes
3answers
313 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 ...
2
votes
2answers
331 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 ...
1
vote
1answer
121 views

How to get screen coordinate from geographic one?

I need to know, how can I convert some geographic coordinates to the screen one. I want to remind you about desktop coordinates system, how it look like: I've developed soft, which is loading map ...
3
votes
0answers
89 views

How can I convert 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
votes
1answer
138 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 ...
1
vote
0answers
212 views

Locating the centroid (center of mass) of spherical polygons

I'm trying to work out how best to locate the centroid of an arbitrary shape draped over a unit sphere, with the input being ordered (clockwise or anti-cw) vertices for the shape boundary. The density ...
2
votes
1answer
285 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 ...
3
votes
2answers
257 views

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 ...
2
votes
1answer
100 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
votes
0answers
57 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 ...
0
votes
1answer
536 views

Specifying a rectangle as two latitude/longitude pairs, one for center and one for size

I am trying to make sense of the Google S2 library for spherical math (it works like this). I need to get a rectangle for searching for nearby entities in a database, based on a point and a distance ...
2
votes
0answers
197 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 ...
1
vote
0answers
17 views

Finding the exact coordinates of circle's extreme east and west points on a sphere [duplicate]

I'm currently implementing the Bentley-Ottman algorithm applied to spheres, involving intersections of many spheres on one sphere, circles in most cases of course. This requires locating "event" ...
1
vote
1answer
749 views

Transform 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: ...
4
votes
1answer
73 views

What information is needed to determine the section of the earth's surface visible in a photograph?

What information (either provided by a user or taken from sensor readings) would be required to determine the geographic area encompassed by a photograph? It seems like the area visible from a ...
0
votes
1answer
144 views

Rhumb lines intersection

I looking for algorithm how to find out whether two rhumb lines given by point1 with azimuth1 and point2 with azimuth2 have intersecting point. Have anyone idea how to find intersection ? For ...
13
votes
2answers
2k views

What is the approximate error of the Pythagorean Theorem vs. Haversine Formula in measuring distances on a sphere at various scales?

Many people when first trying to calculate distances between two longitude / latitude pairs ask if Pythagorean theorem works as an appropriate distance function. Most often people answer "no, the ...
1
vote
1answer
142 views

How to calculate smallcircle on sphere

I use this python code to calculate a greatcircle: https://code.google.com/p/pyroms/source/browse/trunk/pyroms/greatcircle.py?r=39 After initializing the greatcircle I can calculate points on the ...
3
votes
1answer
821 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 ...