What Is an IGS File?

An IGS file could be an IGES drawing or a Renderer 3D scene

What to Know

This article explains what IGS files are, how to open one, and, depending on the format, how to convert one to STL, STP, DWG, DXF, and others.

What Is an IGS File?

A file with the IGS file extension is most likely an IGES drawing used by CAD programs for saving vector image data in an ASCII text format.

IGES files are based on the Initial Graphics Exchange Specification (IGES) and used to be a widely used standard for transferring 3D models between different CAD applications. However, lots of programs also rely on the STEP 3D CAD format (.STP files) for the same purpose.

Some files that end in .IGS might instead be Indigo Renderer scene files used by either Indigo's Renderer or RT program. These, after having been exported from a 3D modeling program like Blender, Maya, Revit, etc., are then imported into Indigo's software to generate a photorealistic picture.

IGS files in Windows 10 that open with ABViewer
IGS Files.

IGS is also short for technology terms that are unrelated to these file formats, like interactive graphics subsystem, integrated gateway server, IBM Global Services, and integrated gaming system.

How to Open an IGS File

You can open an IGS file in Windows with:

A variety of other IGS file viewer programs include:

You might need a plugin with some of those programs before you're able to import the file. For example, if you're opening it with SketchUp, try installing the SimLab IGES Importer.

FreeCAD is a free IGS opener for Mac and Linux. The TurboCAD Pro and Vectorworks programs linked above can also open the file on macOS.

There are online IGS viewers that let you upload your file to view it online. Autodesk Viewer, ShareCAD, and 3D Viewer Online are a few examples. Since these services are run through a web browser, it means you can use them to open the file on any system, including mobile devices.

Opening the file in some programs might only be possible after it's been converted. See the IGS converters below for more information.

You can also open this file type with any text editor on any operating system, but it's only useful if you want to see all the numbers and letters that describe the file. Notepad++, for example, can view the text within an IGS file, but remember that doing this doesn't actually let you use the IGES Drawing file in the normal way.

If what you have is an Indigo Renderer scene file, you can open it on a Windows, Mac, or Linux computer with Indigo Renderer or Indigo RT.

How to Convert an IGS File

Most of the openers from above can probably convert an IGS file to a different file format. eDrawings Viewer, for example, can export the file to EPRT, ZIP, EXE, HTM, and a number of image file formats like BMP, JPG, GIF, and PNG.

CAD Exchanger is an IGS converter for macOS, Linux, and Windows that supports a huge variety of export formats: STP/STEP, STL, OBJ, X_T, X_B, 3DM, JT, WRL, X3D, SAT, XML, BREP, and a few image file formats.

To open your IGS file in Revit and similar applications might first require that it exists in the DWG format. Convert IGS to DWG with AutoCAD and some other Autodesk programs, like Inventor, Maya, Fusion 360, and Inventor.

An IGS to DXF conversion can be performed with those Autodesk software applications, too.

makexyz.com has a free online IGS to STL converter that you can use to save your IGES drawing file to the Stereolithography format.

Try using the File menu in Indigo Renderer if you need to convert that kind of file. There's most likely an Export or Save as option there.

Still Can't Open It?

If your file doesn't open with the programs mentioned above, or won't save when you try to convert it, double-check the extension. Make sure the suffix reads ".IGS" and not just something that's spelled similarly.

For example, an IGX file could easily be confused with an IGS file even though IGX files are in a totally different file format—the iGrafx document format, and thus require an iGrafx program to open it.

The same could be said for many other file extensions like IGR, IGC, IGT, IGP, IGN, and IGMA. Similarly, although IGS and IOS look similar, the latter refers to the iOS mobile operating system.

The basic idea here is to make sure that you're researching programs that can open the file you actually have. If you have an IGT file and not an IGS file, for example, then look for IGT file openers, converters, etc.

If you do, in fact, have an IGS file that doesn't open with any of the programs from above, run it through a text editor to see if you can find any text within the file that gives away its file format or the program that was used to build it.

  • How do I open an IGS file in AutoCAD?

    The file must be translated and imported into AutoCAD from the Insert tab. Choose Import panel > Import > Find > and select the IGS format from the Import File dialog box. Then browse for the file or type the name and select Open.

  • How do I open an IGS file in FreeCAD?

    To use this free CAD software to open IGS files, go to Preferences Editor > Import Export Preferences > select Part > Import CAD > and choose the IGS file to open. You may also use the File > Import menu option or the Ctrl+I keyboard combination.

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