Value-scale generator

for proportional-symbol maps

example image showing parameters of a proportional-symbol scale
i The lowest of the mapped features' values, usually being the lowest value of the mapped attribute field in the attribute table.
i The highest of the mapped features' values, usually being the highest value of the mapped attribute field in the attribute table.
Symbol shape:
i Desired size (the larger of either width or height) of the symbol representing the lowest phenomenon value in units specified below. You should set this accordingly to the minimum symbol size defined in the Symbology pane of your GIS.
i Desired width (column width or apex-base width) of the onedimensional symbol shapes. You should set this accordingly to the symbol properties defined in the Symbology pane of your GIS.
Symbol-size & column-width unit:
i Desired length of the generated scale (distance between the centers of the smallest and largest symbols) in milimeters. You can specify it according to the amount of empty space in your map layout.
i Number of gaps between short lines dividing regularly the distance between main divisions. You should set this value so that it is easy for a user to estimate more precisely the value represented by any symbol size measured in the map.
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i Font size of the labels located below the scale in typographic points. You can define the scale similarly to size of other textual elements in your map layout according to from which distance and by which users the map is expected to be read.
Typographic style:
i Desired phenomenon values divided by semicolons specifying which divisions (potentially labeled) will be included in the values scale. You can use it to add for example an average phenomenon value or divisions differing from those generated automatically.
optional argument, use semicolon to separate numerals representing values of division lines (e. g. 50; 100; 128.6; 150; 200)
The recently generated result for download: SVG and PDF
preview of resulting value scale


This tool provides a value scale for map legends of proportional-symbol maps (one of the most frequent types of cartodiagrams). The curve represents a function of phenomenon values on x-axis to respective height of map symbols on y-axis. For all supported 2D symbols (circle, square, triangle, pentagon, hexagon ... all being regular), this function follows the principle that the symbol area is increasing accordingly to the phenomenon value. Flannery appearance compensation is not implemented in the algorithm. For one-dimensional shapes (column and apex), the function is linear resulting in a straight line. You may download your output as vector SVG and PDF files. In case of the SVG output, X-axis is labeled using sans-serif Arial font while in PDF using general sans-serif font. In both cases, the labels are easily editable in a graphic software.
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