Poor quality spring import from Creo

Started by thefonzzz, April 11, 2014, 08:13:23 AM

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Hello all,  I'm new here but have been using KeyShot for a few months now.

I am having trouble importing springs successfully from our CAD software (Creo Elements/Direct Modeling).  The spring looks perfect in the CAD software but is horribly jagged once imported into KeyShot (see attached images for comparison).

I've tried altering the Tessellation setting in KS but anything above the default 0.2 just makes it worse.  I've looked in Creo Direct Modeling for any tessellation settings but there doesn't appear to be any - although I'm more used to AutoCAD than Creo!  I usually use STEP files but have tried IGES and DWG so far to no avail  :(

I spent some time reading the forums before posting and found a thread explaining a similar spring issue, but it wasn't resolved (this was KeyShot 3 in 2012 though).

Any ideas what else I can try? The spring is a feature in the closeup render I'm doing and at the moment it looks rubbish!  :(

Thanks for reading.




The good news is that in KeyShot 5 we will have the ability to render NURBS directly, at least in the Pro version. No need to for tinkering with the tessellation. Attached is an image of a spring from Creo which always gave us issues with the tessellation in the past. I would still like to get your file, though.


Thanks for the reply - kinda pleased that it's not me doing something wrong but at the same time it would appear there's not much I can do for now.. at least until KS5 is released..?

Thomas, I've sent you the spring STEP file - thanks for taking a look at it :)


We have a parameter called "Accurate tessellation" which is exposed for CREO files, but not for STEP :-(. Springs are pretty much the only geometry that would require use of this parameter. Can you export to another file format for the time being?


Is 'accurate tessellation' available in KeyShot 4?  At the moment I can only export to IGES/STEP/DWG/SAT/STL/NEU/VRML as I don't have licenses for other export modules..


Okay, found out that a friend has Creo so had him export the spring to PRT format.

The importer in KeyShot 4 displayed the 'Accurate Tessellation' option which I checked, however the model looked the same once imported :'(

Fiddling with the tessellation quality with 'Accurate Tessellation' checked makes no difference.


Checking accurate tessellation and setting the slider to 1 gives you a pretty good result, much better than the image you posted above.

We will add this option for more importers in KeyShot 5.


That's strange, it makes very little (if any) difference for me.  This is the same spring, exported to PRT from Creo Pro and imported into KS with accurate tessellation checked and the slider set to 1..

Could you post your result please?  Any special settings you've applied from Creo or within KS?  :-\

Chad Holton


Was this spring modeled in Creo, or was it originally another file type that was imported into Creo and then exported back out as a PRT file?

I messed around with a spring I had in Creo (originally modeled in Creo) and it looks great when importing using the import method Thomas mentioned. I attached it for reference along with a screenshot.



Thanks for your input.

I believe the spring was originally modelled in Creo Elements/Direct Modeling 18.0.  I sent the native PKG file to my buddy who imported it into Creo Pro then saved out as native PRT file.

I would re-model it but I only have Elements/Direct!  ::)


Thought I'd update this thread in case anyone else is interested and as has similar issues..

I have managed to workaround the problem by using the Okino Polytrans software I've had kicking about on my computer for many years - it looks a little dated now but it's a very, very efficient 3D file conversion tool.  I exported the spring from Creo Element/Direct to the STEP file format, imported to PolyTrans, then saved out to the Rhino 3DM file format.

The 3DM file looks much nicer once imported into KS4  ;D

Thanks to those who posted - hopefully KS5 will be able to handle springs direct from Creo Elemts/Direct better, but for now I'm happy (and relieved!!)