Linked Questions

2
votes
1answer
412 views

confused about distances on the wgs-84 ellipsoid

As far as I understand given a certain latitude the length of a degree of longitude is constant. So using any distance calculator (I use Mathematica here) this equals: (circumference of the earth) ...
7
votes
1answer
3k views

Measuring Angle of two Points from North in ArcGIS 10.3 C# SDK

What is the most reliable method to calculate angle of a line from north, defined by it’s from and to points? I used to use IMeasurementTool interface found in defense solutions namespace found in ...
1
vote
1answer
640 views

Is the Azimuth on the equator equal to the one not on the equator?

I am trying to fully understand the concept of Azimuth and I am encountering some inconsistencies (or maybe it is my error). I show you some examples that do not match, hoping somebody can explain me ...
2
votes
1answer
218 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
329 views

SQL Server geography.Intersects Yields Unexpected Results (arch shape)

I've coupled ESRI's ArcGIS with SQL Server 2008 R2 in an attempt to allow users to search for geographical points using a polygon (with ArcGIS' drawing toolbar). I've run up against an issue that's ...
9
votes
1answer
21k views

Calculating View Angle?

I am looking for the most accurate way of calculating the view angle (Azimuth, Elevation) from a reference point (my location) A to another point B. I have the Lat, Lon, and Altitude for each point. ...
5
votes
2answers
968 views

What is a delta in lat/lon called?

What is the delta between two lat/lon pairs called? Delta degrees? Arcs? Is it some quantity of distance but what is its unit of measurement? And related: Can we use pythagoras to calculate this ...
2
votes
2answers
113 views

What is the difference when measuring in units rather than meters?

I have a function that takes a point and compares it with lines that are stored in PostGIS and then gets the line closest to the point. Initially I did not transform the data because I did not think ...
4
votes
1answer
2k views

How to place markers on the outline of a circle in google maps?

I have the center of a circle and it's radius and I need to place variable amount of markers on the outline/stroke of the circle. The distance between this markers should kept same, so if I have 8 ...
3
votes
1answer
196 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 ...
7
votes
2answers
4k views

Find tangent point on circle furthest east or west

There are few ways of articulating my question. It starts with a known circle on a sphere, i.e. a point-radius, and one that does not cover a pole. I would like to calculate the point furthest west ...
9
votes
2answers
2k views

Is there a way to draw a straight line on a map which also represents a straight line on the earth surface?

I'm trying to understand more on projections. In this example, why must one calculate the curvature of the earth (great circle) if the map is already projected? Is there a way to draw a visibly ...
6
votes
1answer
1k views

Accuracy of planimetric geometry vs. ellipsoidal model

I'm examining the two geospatial options for IBM's DB2 database. In particular I am interested in the accuracy between these two options and whether it's worth it (the more accurate representation isn'...
72
votes
11answers
41k views

What Makes a Map be classed as Badly Designed?

A poorly designed map can not only look visually unappealing, but can convey the wrong message, which could lead to bad decisions being made. I would like to ask people to post examples (that are in ...