While maps are generated, the sign of values presented and the distance from a value on a map to a zero value may be lost. If a selected scale presented is not opened, a user cannot indicate the point at which the sign changes on the map and specify the ratio of minimum to maximum values.
An automatic scale is generated so that negative values of a presented quantity on a map are marked with shades of blue, whereas positive values with shades of red. Created map scale allows both locating the regions where the sign changes and determining the ratio of extreme values.
It is assumed that both color groups may be divided maximally to 128 components. The color scale is created once the extreme values for a given quantity are determined (vmin, vmax). A greater value (in regard to the absolute value) of vmin and vmax is assigned the 128th color (considering the sign of the value). The color of a second value is chosen based on the proportions between vmin and vmax, whereas intermediate colors are ascribed by means of uniform division of a scale. Another thing introduced is rounding of intervals so that zero is one of the limit values on a scale.