OASIS/GDSII to Gerber RS274X

Introduction

The OASIS2GBR program—aka Gerber Extract—converts OASIS or GDSII layout data into Gerber's RS274X format. It is very useful if your CAD tools create GDSII or OASIS and your mask writer accepts only Gerber (RS274X) format.

We also offer this software as a library for OEMs who wish to integrate it into their own tools.

Basic Behavior

The output Gerber units are always in units of MM no matter what the input units.

Automatically recognizes whether input file is GDSII or OASIS

The program is launched by command line

All RS274X output uses the G36/G37 area fill command

RS274X Optimizations

Directly converting OASIS/GDSII to Gerber can result in extremely large Gerber files which can slow down or crash even powerful RIPs. Therefore Artwork has implemented two major optimizations designed to reduce both the file size and increase the speed of the Gerber RIP. These are:

Repetition

Use of the Gerber SR command to take advantage of repeated data which is very often found in panelized data. Details ...

Arc/Circle Recognition

Recognizing a series of short segments as an arc and creating circular data or round flashes in Gerber. Details ...

Command Line Syntax

The library is managed using the gbrxtrakapp64.exe executable. This executable takes the command line arguments and converts them into library calls that run the conversion. For those who want to call the library directly, go to the GerberExtract Library page.

gbrxtrakapp64.exe <input_oasis_file> <output_gerber_file> [OPTIONS]

where

<input_oasis_file>

Path/filename of the OASIS or GDSII file to be translated.

<output_gerber_file>

Path/filename of the translated GERBER output.

[OPTIONS]

-layers:<list>

Comma separated list of layers of interest. If -layers is not present all layers will be merged.

-cell:<name>

Set the specified cell as the view cell for extraction. If no -cell is present the program will choose the top cell automatically.

-window:<minX>,<minY>,<maxX>,<maxY>

Extract data from the specified window.

-nocompress

Disable compression.
Default behavior is -compress which will use SR and arc recovery to minimize output file size.

-mode: compact | speed

Determines which compaction algorithm to use.
Default is -mode:speed

-mode:speed=1

Use when input file has little or none repeating cells and the output file size is not a concern.

-log:<log_file>

Write log to the specified file.

-silent

Suppress stdout messages.

-overlap:overlap_in_file_units

to specify amount of overlap between butting polygons. This was introduced for certain rasterizer which was leaving one pixel gaps where polygons were butting.

-circularize:max_chord_error

The parameter to control the arc recovery process.
If 0 then arc recovery is disabled.

-format:XY

Specify the number of integer and decimal places for co-ordinate data along both X,Y axes. X is the number of integer digits and Y is the number of decimal digits.

Command Line Examples

1. Create data for all layers using the default top cell from an OASIS/GDSII file

gbrxtrakapp64.exe sample_input.gds sample_output.gbr

This will produce a RS274X file for each layer in the layout database since the -layer command line option was not used.

2. Faster conversion as oppose to compact output file

gbrxtrakapp64.exe sample_input.gds sample_output.gbr -mode:speed

This option checks the input file for hierarchy. If sufficient hierarchy is found, it uses an alternate algorithm and emphasizes speed over compaction. If sufficient hierarchy is not found, it uses the the original algorithm for superior compaction.

-mode:compact uses the original algorithm and emphasizes compaction over speed.

3. Create Gerber files for all layers on a specific cell (TEST) from an OASIS/GDSII file

gbrxtrakapp64.exe sample_input.gds sample_output.gbr -cell:TEST

4. Create Gerber files for specific set of layers (1,2:2,3) from an OASIS/GDSII file

gbrxtrakapp64.exe sample_input.gds sample_output.gbr -layers:1,2:2,3

the -layers: argument enables the user to specify a list of layers or layers:datatype to output.

5. Turn Off/Disable the repetition recognition algorithms

gbrxtrakapp64.exe sample_input.gds sample_output.gbr -nocompress

6. Write a log file to disk

gbrxtrakapp64.exe sample_input.gds sample_output.gbr -log:sample.log

7. Suppressing messages to stdout

gbrxtrakapp64.exe sample_input.gds sample_output.gbr -silent

By default, OASIS2GBR will open a window and display progress messages. To suppress this behavior use the command line option: -silent.

Return Codes

If you wish to run the conversion from a script or batch it is useful to know that the program returns one of two return codes:

0 success

1 failure Information about the cause of error is sent to stderr

Gerber Output Specification

The Gerber output format is the same no matter what the input units and resolution of the GDSII/OASIS data is.

Geometry - How Holes/Islands are Handled

The default behavior is to create holes and islands using "cut lines" often referred to as keyhole geometry. This page describes in detail what the output geometries look like and discusses possible options if the current approach causes problems for the mask writer.

example of a reentrant polygon (keyholed) generated to support island or hole.

Platform and Operating System

Windows

64 bit Windows 7/8/10

Linux

64 bit RHEL 5 or higher