There are plenty of maps around, printed and otherwise, with numbered grids that do not directly equate to real-world coordinate systems.

Typically these grids will have 0,0 in the bottom-left corner - at least, in the most of cases that I have personally seen.

This seems to be at least an informal convention. My question is whether this convention is more established?

Are map-makers just gravitating towards something that they think most people will instinctively understand, or are there additional reasons for them to follow this approach?

Background: All developer-created maps and most community-created maps in a particular computer game follow this convention. However a very small number of community-created maps have a Y-axis that goes in reverse, so 0,0 is in the top-left corner.

Not only do players often miss this, and thus misread coordinates, but even in-game tools misread these coordinates - both being one grid out on the Y coordinates.

For example, a point on the map, might be denoted as (0125, 0125) on the grid, but read as (0125, 0135) by the in-game tools.

So as a matter of curiousity, I'm trying to find out which of the following cases is most accurate:

  1. The map is 'wrong' - the convention is that 0,0 is bottom-left
  2. The game tools are 'wrong' - there are additional, competing conventions that use top-left as 0,0, and said tools ought to cater for this eventuality
  3. Neither are wrong - there are no firm conventions and though the many maps might tend towards 0,0=bottom-left, there are lots of other approaches commonly in use.

Note: A whole host of maps have A-Z+ as the x-axis and 0-n as the y-axis, with A1 being at the top-left, but I consider these as separate - these are intended to identify grids squares but not 6 and 8-figure coordinates.

I suspect the answer will be #3 but I will be interested to hear of any background/historical/supporting evidence.

1 Answer 1


The (0, 0) origin marks a placeholder coordinate system, that is designed to make use of standard distance, area and bearing calculations, but do not tie the image-space to a particular point on the planet. There is somewhat of a controversy over whether these maps can be called a "map" in the cartographic sense, or should only be referred to as plants (they are hardly ever used outside of construction blueprints). Regardless, this is not a discussion for now.

Cutting to the center of your question: the origin in an arbitrary coordinate system varies from field to field. There are actually two parameters at play:

  • If the origin is at the lower-left or upper-left;

  • If you reference the coordinates horizontal-vertical, or vertical-horizontal.

Different areas of human knowledge treat these differently. Mathematics treats cartesian planes with the origin in the lower-left (when dealing with positive numbers), and coords in horizontal-vertical (i.e., X and Y). Computer graphics, on the other hand, place the origin in the upper-left, and trace values horizontal-vertical, because of a legacy of how CRT monitors used to work (they'd begin drawing from the top row to the bottom). Matrices, on the other hand, have their origin in upper-left corner, but, read coordinates in the vertical-horizontal way.

The lack of a standard way to read tabular data can lead to confusion when changing fields, so it's important to first grasp exactly how a particular field or tool maps locations to a plane. In the specific case of videogames, the in-game coordinates are arbitrary and may be set to wherever the creator feels like it. It may be lower-left origin to mimick how plants are layed-out, or upper-left to map with the screen blit. Or anywhere else (I've seen games whose origin was at the centre, and objects would have positive and negative coordinates all over).

For a geographic map, however, one should stick to a a real-world coordinate system, which will map your origin to a specific place on Earth, regardless of your mapping area.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.