# Tagged Questions

The measurement and representation of the Earth, its shape and gravitational field, distances on the Earth, and coordinate systems for locating points on it including longitude and latitude.

297 views

### Seasonal changes in hours of daylight

I will post my own answer to this question unless someone else posts the same answer first, but I am curious to know what other points of view might lead to different ways of answering it. ...
2k views

### What is the geodesic between a point and a line (geodesic between two points) on an oblate spheroid?

I found a similiar question that also asks for the distance from a point to a line but works on a sphere. Now I'm trying to figure out the length of the geodesic line ...
99 views

### What property does this equation calculate?

It's pretty difficult to Google for the meaning of a formula. This is the equation, it has to do with ellipses and GIS coordinates. $$\nu =\frac{ a} {\sqrt{(1 - (e^2 \cdot \sin(\varphi))^2)}}$$ $a$ ...
767 views

### Convert LLA (long, lat, alt) to flat earth model

I would like to divide the globe into 1000 $\times$ 1000 meter geodesic squares, and then map any long / lat to the applicable square. The altitude of each block would be the altitude of the earth at ...
105 views

### How much extra sea water is needed?

We might call this the “Noah's Ark” calculation, but in the movie Waterworld (1995) they have the icecaps melting and take poetic license making the ~$220$ feet or so of sea water (one estimate I've ...
884 views

### Solving geodesic problems with Euler-Lagrange equation

This is the question: Problem B.1 Two cities - Tel-Aviv, Israel and SanDiego, CA - have the same latitude 32 ◦ N, but, diﬀerent longitudes: Tel-Aviv is 34 ◦ E and San-Diego is 117 ◦ W. What is the ...
2k views

### How to find a (longitude, latitude) point on a circle when given only the center (longitude, latitude) point and radius measured in Feet

How do I find a (longitude, latitude) point (any will do) on a circle where the only info I have is a (longitude, latitude) center point, and a radius measured in Feet (ft.)?
48 views

### Relation between differential geometry and differential geodesy

I am not exactly clear on what are the differences between differential geometry and differential geodesy. Are principles in differential geometry used in differential geodesy ? It appears that ...
151 views

### Wind vector transformation from Gaussian grid to displaced pole grid

I have been given the "u" and "v" component with respect to an earth coordinate reference system(Gaussian grid - https://en.wikipedia.org/wiki/Gaussian_grid http://www.nco.ncep.noaa.gov/pmb/docs/on388/...
331 views

### Drawing a Great Circle between two given points on Earth

I need to draw a great circle arc between two latitude and longitude points. For sake of example we will use the coordinates for LAX and JFK. JFK is 40.64°N / 73.78°W LAX is 33.94°N / 118.41°W ...
360 views

### Literature of Geographic to Cartesian Conversion

When I was looking for info on converting latitude/longitude to $(x,y)$ Cartesian coordinates, I found this link on Doctor Math. I found this following formula: In Radians: x = (\text{lon}_2 - \...
287 views

### Distances are different by ~100-200m

I'm measuring distance of 2 points on Google Map and then in my program converting them into ECEF using this formula. Then using Pythagorean theorem to calculate distance between those 2 points. ...
47 views

### Latitude Drift using Vincenty Direct Formula

I am impostor here, and am by no means mathematically literate, so please bare with me. I have posted a software question on StackOverflow, regarding an unexpected drift in latitude using Vincenty's ...
95 views

### Find Latitude of point given Longitude and Great Circle orientation

Given the orientation of a great circle as the cartesian components of the normal vector $(a,b,c)$ to its plane, i.e. all points on the circle described in Earth-Centered Earth-Fixed (ECEF) ...
153 views

### Calculate a point on a geodesic line on an ellipsoid

I have a problem which i don't understand how to achieve. Maybe someone could sheed some light on it. Have a look at this picture: What I try to achieve is to determine the point D on the geodesic ...
388 views

### Maximum latitude of a great circle

1 - I am trying to figure out the longitude at which a geodetic great circle reaches its apex. (I have a point and the azimuth at that point identifying the circle) I have found a good resource that ...
81 views

### Radius of the Earth at N32.704220, W90.000000?

I want to express a point on a map in radian spherical coordinates. By Google maps, this location is north of Canton, MS, USA just a few hundred feet from US 51. In radian spherical coordinates, \$(?,-...
150 views

### Algorithm for Stepping Through Latitude, Longitude and Height with a Heading

I have a function which reads in latitude, longitude, height, heading and step size. My function should calculate the latitude, longitude and height of the position one step size away in the direction ...
15 views

### Oblate Spheroidal Coordinates, Confocal Ellipsoidal Coordinates and Geodesy

What is the name of the orthogonal coordinate system that is most commonly used in modern geodesy\geomatics engineering to model the reference ellipsoid? I suspect it is either oblate spheroidal ...
40 views

### Translation matrix in spherical coordinates system

I'm using WorldWind software to draw segments (polyline) on the globe to materialize an aircraft flightplan. Each point in a flightplan is named waypoint. Waypoints are expressed in geographical ...