I'm working on an independent high school project where i'm trying to build a simple differential equation model for diffusion. I'm trying to overlay the model on top of a map to visualize spread, so for example, oil in water.

Right now I have a rectangular box that have the coordinates of ( 31.0195,-102.8072) NW, (19.2019, -102.8072) SW, (31.0195, -75.3963) NE, and (19.2019, -75.3963) SE. I am trying to build a 2D array of lat/long coordinates spaced evenly. For example, an array of lat/long coordinates that are 500m apart.

Is there a formula/algorithm where I can convert these coordinates to a distance, break the distance up into 500m chunks, and then get lat/long coordinates along the way (i.e. so I have lat/long coordinates every 500m)?


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    – Martin F
    May 21, 2014 at 0:32

1 Answer 1


As you're dealing with a very large curved region, you cannot get an array that has regular intervals in both angular units (degrees Lon-lat) and linear units (meters E-N).

The topic of map projections concerns this mapping of the curved earth to a flat map, and hence geographic coordinates (lon-lat) to map coordinates (E-N).

The topic of spherical geometry concerns conversion between geographic coordinates and linear distances.

This question may help: calculating distance between two latitude-longitude points.

Things to consider:

Do you want fixed linear intervals (not really compatible with what you're starting out with), or a fixed number of intervals and hence fixed angular intervals?

Depending on that, you may need to calculate the three side lengths of the "rectangular" box? The N-S lengths of the left and right sides are the same, while the E-W lengths of the top and bottom are different.

Do you have any restrictions on software you can use?

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