AirWare   On-line Reference Manual

  Release Level 5.4
  Release Date 2008 10
  Revision Level 1.0

Display Colors

The display of model results over user selected background maps is based on a set of color scheme definitions.

Two different systems are being used:

  1. pre-defined, static arbitrary (non-linear) color ranges, defined for any or all combination of
    • pollutant;
    • aggregation period (1,8,24, 8760 (annual) hours).
  2. a (default) dynamic color definition.
The color are defined in a simple ASCII configuration file, /var/www/cgi-bin/mapcolor.
Dynamic default color range
The first entry in the file consists of 21 decimal, integer RGB color definitions:
    0 0 255
    0 100 255
    0 150 255
    .........
    255 100 0
    255 75 0
    255 50 0
    255 0 0
    150 0 0
The interpretation is as follows: the range between a user-defined minimum and maximum concentration is divided into 20 equal intervalls, each being assigned one of the first 20 colors; this range (in terms of minimum and maximum) can be dynamically re-defined. Values below the minimum are invisible (transparent); values above the maximum (open ended) are displayed in color 21.
Named, static color ranges
Separated by a blank record, any number of named color definitions follow. Their first record consiste of a variable (pollutant ) name, and an aggregation period in hours:
    O3_ppb     1     3
would indicate ozone in ppb, hourly values, and a MIN (starting) concentration for the first concentration range and color of 3. This header is followed by any number of color range definitions, defined by their upper limit value:
    0 0 25512
    0 100 25524
    0 150 25536
    0 255 15048
    ... .........
    255 50 0360
    255 0 0400
    150 0 0
The file consists of the three decimal, integer RGB definition, values and the upper limit of the corresponding color range (concentrations lower or equal that value, and larger than the previous bound, are shown in the corresponding color. The first range start at the MIN value defined in the header (concentrations below MIN are invisibble); The last range is open ended.

Implementation strategy

Any model output display always shows one well defined combination of pollutant and aggregation period: the model scenario has either a single substance and aggregation period, or selectors for several pollutants and periods.

Whenever there is color scheme defined for this combination of pollutant and aggregation period, this is being used automatically to render the results.

  • Color definitions starting at a lower limit of 0 (and thus covering the entire model domain and map window) are rendered transparent as the default;
  • Color definitions starting with a lower limit >0 are rendered opaque as the default.

If no color scheme has been defined for a given combination, the default (dynamic) scheme is used with an initial default of MIN and MAX values taken a second configuration file, /var/www/cgi-bin/colorranges This uses the following format:

    where the first record contains the definition of a global default, used when the dynamic scheme is selected, but no default definition corresponding to the current combination of substance/aggregation period can be found.
    Please note that POLLUTANT_NAME is the (internal) name of the corresponding Descriptor defined in the systems knowledge base.

    ANYANY 1 100
    POLLUTANT_NAME PERIOD MIN MAX

    Interactive selection and configuration

    At the level of the scenario display, the color bar under the map is used as a trigger for a color scheme selection dialog: A pop-up window shows the current selection:
    • predefined or dynamic
    • lower and upper bounds,
    • transparent/opaque switch.
    Interactive changes:
    • the user can toggle the transparent to opaque selection;
    • IF the default color scheme is pre-defined (regulatory interpretation), the user can switch to the dynamic schem and change the display bounds;
    • IF the default scheme is already dynamic, the display bounds can be changed.
    Any such modification will only be valid for the current session. No interactive changes will affect the rendering of the automatically generated forecast and nowcast imagery at the first page, multi-time step diaplys or animation.

    Any long-term and permanent re-definition must be done by editing the color configuration file.


    Development notes

    The color configuartion dialog will also be available from the Details page; however, while change at the scneario level remain effective duriung a given session, any changes made at the details page level will, by default, only be effective at this level. An toggle switch on the dialog can enforce thei propagation to the upper (scenario) level.

    The direct interactive editing of the individual concentration range boundaries and the corresponding RGB values is planned for future releases.

    The interactive editing of the color CONFIG files is planned for future releases.


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