Convert IGES to OBJ
This is the conversion for getting an old CAD file into a modelling or rendering program. OBJ is what Blender, Maya, Cinema 4D and every render pipeline expect, and IGES is what industrial archives are full of. The bridge between them is a CAD kernel, and it runs here in your browser.
Drag a 3D file here, or.
This page is set up for IGES files. Other formats we can read work here too.
The file is read on your own computer. It is never uploaded.
Your file is read by your own browser and never sent to a server. There is no upload, no account and no copy of your model anywhere but on your computer.
Surfaces become named objects
An IGES file is built from surface patches — a trimmed plane here, a piece of a cylinder there — and each one is a separate thing in the file. That structure survives the conversion: each surface arrives as its own named object in the OBJ, so a model comes into Blender as a set of pieces rather than one undivided mesh.
This is useful and occasionally surprising. A part that looks like one object in a CAD viewer can be a dozen surfaces in the file, and the OBJ will have a dozen objects in it. Join them in Blender if you want one; the alternative — merging them here — would take away a choice you cannot get back.
Gaps do not matter as much here
IGES surfaces frequently do not quite meet, which is a serious problem for 3D printing and a minor one for rendering. A viewport does not care whether a model encloses a volume; it draws what is there.
So a file that would be rejected by a slicer is often perfectly usable as an OBJ. The closed-shape line under the 3D view still tells you the truth about the model, but for rendering work you can generally ignore it. If you plan to boolean or subdivide the result later, that is when the gaps start to matter and it is worth sewing the surfaces in FreeCAD first.
Set the detail for a viewport, not for a machine
The triangles are made during the conversion, and the setting that decides how many is above the model. For rendering, the right amount is the least that looks correct from the distance you will see it.
Start at Draft and look at the curves in the 3D view. Move up only if they show. A surface-heavy IGES model at the Fine setting can produce a mesh large enough to slow a modelling program down, for a difference nobody watching a render will notice.
Up axis, and the rotation everybody forgets
CAD treats Z as up. Blender, Maya and most render engines treat Y as up. An IGES model dropped straight into Blender therefore arrives lying on its side, and rotating it afterwards means remembering to apply the rotation before anything else in the scene depends on it.
Set the output up axis to Y before converting and the file is written the right way round. The coloured marker in the corner of the 3D view shows which axis will be up in the file you download.
What survives, and what does not
Kept in the OBJ file
- Each surface in the file as its own named object
- The shape to the tolerance you choose, and the size the file declares
- A properly connected mesh, with duplicate points merged and faces made to agree
Lost on the way
- The exact curved surfaces — they become flat triangles and cannot be turned back
- Colour and layer information, which this conversion does not carry across
- Watertightness, when the IGES surfaces did not meet in the first place
How to convert IGES to OBJ
Drop the .iges or .igs file in
Either extension works. The first CAD file you open downloads the CAD engine, about 3 MB, and it is cached after that.
Start with the detail on Draft
For rendering, the right density is the lowest that looks right. Raise it only if the curves visibly show in the 3D view.
Set the up axis to Y
CAD is Z-up and Blender is Y-up. Changing it here means the model arrives upright rather than on its side.
Check the object list
Each surface becomes a named object. Switch off any you do not need — this is the easiest place to cut the size of a large surface model.
Convert and import
If the model had colours you will get a zip with the .obj and its .mtl; keep them in the same folder. Otherwise it is a single .obj.
IGES and OBJ compared
| Property | IGES.iges .igs | OBJ.obj |
|---|---|---|
| File contents | Plain text in fixed 80-character records, divided into five labelled sections. | Plain text, one item per line. Materials live in a separate .mtl file beside it. |
| Geometry | Exact surfaces and curves, often as unstitched trimmed patches rather than a solid. | Triangles and polygons. Also stores free-form curves, which almost nothing writes. |
| Units | Recorded in the global section, as one of eleven fixed unit codes. | None. Like STL, the numbers are bare, though exporters usually mean metres. |
| Colour and texture | A colour number per entity, from a small fixed palette. | Material names and texture coordinates, with the materials themselves in the .mtl file. |
| Separate objects | Flat. Assembly structure is weak and frequently lost. | Named objects and groups, each able to carry its own material. |
| Published by | The US National Bureau of Standards, 1980. Frozen at version 5.3 in 1996. | Wavefront Technologies, 1980s, for the Advanced Visualizer. |
| Written by | Older CAD systems, and current ones when a customer asks for it. | Blender, Maya, 3ds Max, ZBrush and most modelling programs. |
Questions
- Why did one part arrive as a dozen objects?
- Because that is how the IGES file stores it. IGES is built from surface patches and each one is separate in the file. Select them in Blender and join them if you want a single object.
- Does it matter that the model is not watertight?
- Not for rendering. It matters if you plan to boolean, subdivide or 3D print the result. Sewing the surfaces in FreeCAD first is the fix, or ask the sender for a STEP file.
- The model came in on its side. Why?
- CAD programs treat Z as up and Blender treats Y as up. Set the output up axis to Y before converting.
- Nothing converted and it said there were no surfaces.
- The file holds only curves and points. IGES is used for wireframe and 2D drawings as well as models, and a wireframe cannot become a mesh. Ask for a file with real surfaces in it.
- Is anything uploaded?
- No. The CAD engine runs in your browser and the file never leaves your computer.
Where to go next
Other things to do with a IGES file
Other ways to get a OBJ file
Related guides and tools
- Repair an STL that will not sliceClose the holes and separate the bad edges so a slicer accepts it
- Reduce the size of an STL fileFewer triangles, the same shape, a much smaller file
- Check whether an STL is ready to printFind out what is wrong with a model before you print it
- Convert BLEND to OBJGuide
- Convert BLEND to STLGuide