SFGEN Manual

Copyright 2013-2017 , Artwork Conversion Software, Inc.

updated: August 17, 2017 for v2.42

updated: March 17, 2020

Table of Contents


Graphical User Interface

  Main Dialog

  Advanced Settings

    Panel Flow

    LCD Flow

      Span Length Details

Command Line Syntax




    Panel Flow

    LCD Flow

  Distortion Correction




Linux Notes


SFGEN is a preprocessor which reads either GDSII stream files or ODB++ printed circuit board manufacturing data files. It is designed to be used to produce an optimized GDSII file for Artwork's Real Time Correction RIP (RTCR). In order to get maximum throughput out of the RIP we rely on the fact that large panels or LCDs contain repetitive data.

The SFGEN program identifies such repetitive data and separates it from the background (or frame) data that is not repetitive. This enables the RIP to effectively place a large number of pixels using bitmap copy as opposed to rasterizing the entire panel by brute force. As the bitmap copy is much faster than re-rasterizing the same input data over and over again, the net result is faster rasterization.

The output of the SFGEN program is a GDSII stream file (no matter whether the input is GDSII or ODB++) and it has a limited hierarchy optimized so that the RIP need do as little rasterization as needed.

Graphical User Interface

Start up SFGEN

The main dialog will appear:

SFGEN main dialog

Input File/Directory

Use the Open button to select (open) either:

Once you have selected the file, SFGEN will scan it, verify it is OK and will provide a list of Steps/Layers (for ODB++) or Cells/Layers (for GDSII) for you to select when running the conversion.

Output File/Base Name

Output Layer

Output Cell

View Output





Example 1 (ODB++)

In the example below the user opened the ODB++ file called: 226.tgz and selected the step called "array" and selected the layer named "top".

SFGEN main dialog with ODB++ loaded and step/layer selected

Example 2 (GDSII)

open dialog for a GDSII file

Advanced Configuration

The advanced configuration is a tabbed dialog that enables the user to control the conversion settings, to define transformation, to define text annotations that will be dropped into the raster output and to load a distortion data file that can be used to compensate for distortion in the substrate.

Processing Flows

There are three data flows supported by SFGEN:

So if you open an ODB++ file, you are, by default, in Panel mode.

three operating flows


Settings Tab (Panel Flow)

If you have loaded an ODB++ file the only available flow is PANEL. The check box to select LCD or GDSCompact is grayed out.

Advanced Settings Dialog (ODB panelized input)

Working Dir

Thread Num

Optimize SR

Append Log File

Show Progress

Keep Temp

Open Args

Arc Resolution and Chord Error

Arc Resolution

illustration of arc resolution

When converting from ODB++ to GDSII this controls how arcs and circles are broken into segments.

Chord Error

illustration of arc chord error

When converting from ODB++ to GDSII this controls how arcs and circles are broken into segments. [This parameter was once called arcsag.]

User Grid


Max Points


polygon output options

LCD Flow and Parameters

GDSCompact Flow and Parameters

Convert Args


Transformation Tab

Advanced Settings Dialog


    Enter the DPI that the RIP will use. This value (in conjunction with the buffer size) is used to determine the size of the repetitive geometries so that the RIP will have an optimum input.

Buffer Size

    Enter the buffer size (this value is used in conjunction with the DPI) that the RIP will use to hold the repetitive data. This is not the raster buffer size but a separate buffer dedicated to holding the bitmap masters.

Scale X

    Enter the scale X factor and the anchor coordinate. See Reference

Scale Y

    Enter the scale Y factor and the anchor coordinate. See Reference

Mirror X

    Check to enable mirror X (i.e. X -> -X) also enter the anchor coordinate. See Reference

Mirror Y

    Check to enable mirror Y (i.e. Y -> -Y) also enter the anchor coordinate. See Reference


    Enter a Rotation value in degrees (increasing angle is CCW) and an anchor point about which the input data is rotated. See Reference

Shift (X,Y)

    Enter the shift along X and Y.

Offset (Edge Bias)

    Select the offset mode: NONE, INNER, OUTER, BOTH. See the reference section for details as to how INNER, OUTER and BOTH are implemented. Reference.

Order of Transformation

The transformations are performed in the following order:
  1. Scaling
  2. Mirror X
  3. Mirror Y
  4. Rotation
  5. Translation (Shift)

all units are in microns except rotation which is in degrees

Annotation Tab

This tab enables the user to load an annotation file. The annotation file contains one or more annotation entries that instruct SFGEN to generate text (or to "annotate" the mask.) This text is usually some sort of an identification, lot stamp or date stamp associated with the actual writing of the mask.

advanced settings: annotation tab

If the Add Text check box is selected, the user should also select an annotation file by using the Browse button. (Checking the box and failing to select a legal annotation file will cause a conversion failure ...)

The annotation file can be created by hand, by an application or by a Qckvu3 plug-in.

The syntax and details of the annotation file are here.

Distortion Tab

Advanced Distortion Dialog

Distortion refers to a correction applied to the CAD data in order to warp the CAD data so that it "fits" on a substrate that may have been subject to some physical distortion due to either temperature or possibly processing (such as etching one side). Distortion can be corrected either in the SFGEN program or it can be corrected in the RTCR.

The correction works by reading the coordinates in a table of common points from both the CAD data and the measured on the substrate. These points drive a correction engine that attempts to match the distortion found on the substrate. Of course, there is no guarantee that the distortion can be exactly matched from only a relatively small number of data points.

See the reference section for details and examples.

Use Correction File

If checked, SFGEN will read the user specified correction file and apply corrections to the output file. Use the browse button to select the appropriate text file containing the coordinates.


A value (in microns) used to determine whether an instance of a cell is equivalent to other instances. If this value is set too small, each bitmap placement will require its own definition and the RIP will not run very quickly. See the reference section on distortion to understand how the tolerance affects repetition and RIP throughput.

Optional Arguments

Reserved for use by the developers during debugging.

Path Recovery - Introduction

When SFGEN processes an ODB++ file, the circuit traces (aka lines or paths) are converted into GDSII boundaries due to the fact that the ODB++ data is run through Boolean operations during the conversion. So the output from a PCB (sample.tgz layer=top) consists solely of boundaries.

a PCB top layer snapshot shown using the VUV ODB++ viewer. The blue highlighted line is a trace between two pads.
after conversion to GDSII all of the ODB++ pads and traces are unionized and become boundaries.

The path recovery function examines each of the GDSII boundaries and tries to determine if it was originally a path connecting two pads in the source ODB++. If the identification is successful, then it will replace the boundary with a GDSII path (of the appropriate width) along with new boundaries representing the pads on either end of the path.

example of path recognition - most but not all traces from ODB++ are recognized and converted to GDSII Paths.

There are some limitations -- not every pad/path combination in ODB++ can be identified reliably and converted back into a combination of boundary/path in GDSII. There are a number of tuning parameters when using Path Recovery that can affect which traces are recognized.

Command Line Usage

The Path Recovery engine can be run from a command line but only on a GDSII file that was converted from ODB++ using SFGEN. You cannot use the engine directly on an arbitray GDSII file.

For details on the command line syntax go to this page:

Path Recovery Command Line.

Path Recovery Dialog

To activate path recovery, press the Advanced button on the main menu which will take you to the tabbed Advanced Settings dialog; select the tab: Path Recovery.

Then check the box next to Path Recovery.

use the Path Recovery tab from the Advanced Settings

Controls and Parameters

The Path Recovery function includes a large number of controls and parameters that can be adjusted to "tune" the path recognition routine as well as to control the output.

Output Layers, Boundaries, Paths

Path Recovery produces a GDSII output which includes: paths (from traces/lines) pads (boundaries that have been recognized as pads) and boundaries (everything else). By default all three of these outputs are placed on layer 0:0 (where 0:0 indicates layer:datatype)

user control of layer assigned to path, pad and boundary output

However the user can specify the layer for each of the three groups by filling in the appropriate layer numbers.

For example, if 10,20,30 is entered into the field for this control then:

    Boundaries : 10

    Paths : 20

    Pads : 30

separation of output data to boundaries, paths and pads.

Controlling What Gets Output from Path Recovery

Depending on the user's requirements, Path Recovery's output can be filtered. This section of the dialog window controls what gets output.

controlling output

Allow Singlets

If "Allow Singlets" is checked, then a straight path connecting two pads will be passed to the output.

compare output using allow singlets

Include Pads

If "Include Pads" is checked, then any boundaries that are recognized as pads are output to the specified pad layer.

Participating Only

If "Participating Only" is checked, then only pads that terminate a path are output to the pads layer. Standalone pads are not output to the pad layer.

If particpating pads is checked, then only pads that are attached to a path/trace are passed to the output GDSII.

Termination Requirement

Choose one of the three path termination options:


    If checked, then all paths are converted - even those that don't have a pad termination on either end of the path.

    Singly OK

    If checked, then paths that have either a single termination (or both sides terminated) are converted.

    Double Terminated

    If checked, only paths that have both ends terminated are converted.

    Output Source Path Data (positive only) on Layer L[:D]

    This is a debugging feature and is used if one needs to examine the boundaries that were the source for the path conversion. Most users have no need to check this. If you do check this make sure to specify a layer (or layer:datatype) that does not match any of the main outputs for boundaries, paths or pads.

Parameter Fields

The parameter fields can be used to "tune" the recognition of paths. However the actions of each parameter are fairly obtuse and in most cases adjusting these requires a deep understanding of both the program operation and the nature of your data.

In most cases, the only parameter to adjust would be the "Nom. Width" by entering a value that is approximately the width of most of the paths one expects to recover.

The values in the parameter section influence which paths ar recovered.


    Defines a value in microns used for precision associated with general computations and vertex matching (default: 1um).


    Specifies value for removing very thin data associated with boolean operations (default: 10 times chord error).

Min Width

    This option allows the user to set the minimum trace width. The program will ignore any path candidate with width lower than the value defined.

Max Width

    This option allows the user to set the maximum trace width. The program will ignore any path candidate with width greater than the value defined.

Percent Area

    A user defined value in percent used to not output candidate path data whose percent area relative to its extent box is greater than the value defined as path data (default is 25%).

Aspect Ratio

    A user defined value where candidate path data whose length to width ratio is less than this value will be not be output as path data (default is 5).

Arc Resolution and Chord Error

Arc Resolution

illustration of arc resolution

When converting from ODB++ to GDSII this controls how arcs and circles are broken into segments.

Chord Error

illustration of arc chord error

When converting from ODB++ to GDSII this controls how arcs and circles are broken into segments. [This parameter was once called arcsag.]

Nominal Width

    Sets a value to be used by path recovery engine for automatic selection of conversion parameters. Value is in microns and should be set to a typical path width in the file.

Retain Reference File

    This option retains the reference input GDSII file created by SFGEN and passed to the path recovery engine. The reference file will derive its name from the output file with the trailing tag '_ref.gds'.

Other Arguments

    Allows the user to pass additional command line options to the path recovery engine. These include:

  • -keep
  • -id_selected
  • -selected_connected_sets:n[,m,...]

Path Recovery Using the SFGEN User Interface.