English

How To: Make an internal colormap for an ESRI Grid using ArcInfo Workstation

Summary

Instuctions provided describe how to make an internal colormap for an ESRI Grid using ArcInfo Workstation.

Procedure

Using the colormap values, range 0 to 255, add a 'Red', 'Green' and 'Blue' item to the grid's VAT. Each item should be defined as storage width 8, output width 18, type Float and 15 decimal places.
Divide each value by 255 to recieve a decimal percentage, and place it into the respective value/item.

  1. Add the Red, Green and Blue items to the Grid's VAT.

    Arc: TABLES
    Tables: SELECT drg_grd.vat
    12 Records Selected.
    Tables: ADDITEM
    Usage: ADDITEM <info_file> <item_name> <item_width> <output_width>
    <item_type> {decimal_places} {start_item}
    Tables: ADDITEM drg_grd.vat red 8 18 f 15
    Tables: ADDITEM drg_grd.vat green 8 18 f 15
    Tables: ADDITEM drg_grd.vat blue 8 18 f 15

  2. Calculate the RGB value to insert into the new fields. Each value should initially be in a range of 0 to 255. They must be converted into a range of 0 to 1 by dividing each by 255. For example the color 10,215,127 would become 0.0392,0.8431,0.4980.
  3. Add the calculated values to the new items in the VAT.

    Tables: RESELECT value = 1
    Tables: CALCULATE red = 0.0392
    Tables: CALCULATE green = 0.8431
    Tables: CALCULATE blue = 0.4980