I have seen this style of map images repeated in several articles, but was never able to find the software required or a method to reproduce them. Does anyone know how to obtain them?
Nice map, good sample of usability. Use Photoshop for Win, or Pixelmator for Mac, or any other relevant image editor. There are plenty possibilities for creativity here...
Question was not about "a good software for spatial data". Question was about "style of map". Image editor is reasonable tool for editing images for journal article with specific style requirements.
And I guess no universal tool for "spatial data" as well. For example, proposed "style of map" looks like prepared in ERDAS (for my opinion). But ERDAS focused on raster spatial data and is not best for vector data, of course.
"I believe using photoshop on figure contaning a map should be illegal"
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M. Alvioli, why? What prohibits using of raster editor to provide style for the Figure - changing fonts, colors, etc? Raw data for scientific articles could not be intentionally corrupted, of course, but it is not a matter of software. No special limitations in terms and conditions of Photoshop or other image editors. Moreover, Photoshop is officially integrated with ArcGIS, for example:
Esri ArcGIS has the best style format and layout provision than any other software. Since its a paid version, but for students its 100$ for a year where you will get access of ArcGIS Desktop, ArcGIS Catalog, ArcGIS Pro, ArcGIS Online etc.