Wikipedia:Reference desk/Archives/Mathematics/2019 November 7

= November 7 =

Software for plotting custom map projections
I have defined a projection by simple functions relating latitude and longitude to x and y coordinates. I would like to try this out as a proof of concept, and presume that software exists that can do this, but what? I do not need especially high quality imagery, just enough to test the viability of the projection.--Leon (talk) 11:06, 7 November 2019 (UTC)


 * Matplotlib basemap is a well-known Python library for Earth-plotting, projections etc. but the manual says it a has a certain number of predefined projections to choose from. Maybe fudging the source code to include yours is easier than starting from scratch, or maybe not. Tigraan Click here to contact me 12:47, 7 November 2019 (UTC)


 * One option is to use those functions to define a lookup table, first, say of 15 degree boxes, initially. You can then plot the output points in the table (without landforms) to see if they define a rectangle, if that's your desired output. Once it passes that test, then find a program that accepts a lookup table (you may need to reformat it) as input for Earth mapping. You would also need to define how to interpolate between the points in the table, with the simplest option being a 2 dimensional linear interpolation. The less space between points in the table, the less critical the interpolation method will be. SinisterLefty (talk) 14:06, 7 November 2019 (UTC)


 * A better option may be to find a library of landforms specified in longitude/latitude pairs, at various resolutions, which you could use as inputs to your functions. You could then create an output table of those landforms, in X-Y coords. It should be far easier to find a program to plot those. For the initial "proof of concept" stage, you wouldn't need to connect the dots. SinisterLefty (talk) 14:23, 7 November 2019 (UTC)


 * There is a mapping package for GNU Octave. Really depends on how you want to implement your projection if you haven't already.&mdash;eric 15:31, 7 November 2019 (UTC)