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Bug: Polygons are divided in tiny strips when exported to EPS, PDF, CGM, or AI Illustrator

Description

When an ArcMap generated EPS, PDF, CGM, or AI Illustrator file is opened in an external editor, like Adobe Illustrator, some large polygons are divided into thin vertical strips.

The Adobe Illustrator export format was not available until ArcGIS 8.1 Service Pack 1.

Cause

This is called polygon dicing, and is implemented on polygons containing more than 20,000 vertices. The purpose is to speed up on-screen drawing and output to a printer.

Workaround

Try one of these options to reduce the effect of polygon dicing:

  • Simplify the polygon data.
  • In ArcGIS 8.1.2 and later, you can use the following Visual Basic code to turn polygon dicing off and on.

    Run this code prior to exporting your map:

    Code:
    Public Sub turnOffDicing()

    Dim pGeometryEnv As IGeometryEnvironment3
    Set pGeometryEnv = New GeometryEnvironment

    pGeometryEnv.DicingEnabled = False

    End Sub


    Warning:
    This code will not work with CGM files. Unexpected results can occur when exporting to CGM with polygon dicing turned off.

    To turn polygon dicing back on, run this code:

    Code:
    Public Sub turnOnDicing()

    Dim pGeometryEnv As IGeometryEnvironment3
    Set pGeometryEnv = New GeometryEnvironment

    pGeometryEnv.DicingEnabled = True

    End Sub


    Warning:
    Turn polygon dicing back on after exporting, otherwise screen drawing and printing performance may slow considerably.