How to get smoother STEP 3D body curves in Altium? - Page 1
Forum section: electronics / general

author: ARQuattr
author_rank: Contributor
timestamp: September 21, 2013, 03:07:46 pm
content: I'm trying to add a 3D body in Altium from a STEP file that has a larger radius curve. The STEP file was exported from SolidWorks, and if I open it again in Solidworkds the curvature is preserved, but when the body is imported in Altium it becomes a three-sided prism.Is there a way to improve the resolution of the curves?This is what it looks like in SW and after being imported in Altium:

author: JDubU
author_rank: Frequent Contributor
timestamp: September 21, 2013, 04:07:17 pm
content: Have you tried checking the "Export 3D Curve Features" checkbox in the STEP options dialog ("Options..." button at bottom of STEP file save dialog box)?

author: ARQuattr
author_rank: Contributor
timestamp: September 21, 2013, 05:15:55 pm
content: Thank you for replying. Yes, I tried that, but when I try to add the body in Altium I get nothing. It goes through all the same steps but there's nothing - it's as though it's an invisible body. Unless I'm doing something wrong.

author: andersendr
author_rank: Regular Contributor
timestamp: September 22, 2013, 11:29:09 pm
content: I am no Altium expert, but it looks like a rendering issue in Altium. I use Solidworks quite a bit and there are rendering options to set how much a shape looks like a shape. If I am doing really precise work, Ill set the rendering to high so a circle looks like a circle and not a bunch of straight lines. During my normal use I turn it way down to get better performance and then a circle looks like a bunch of straight line. See if there are any rendering options in Altium. If you want to play with these in Solidworks, go to the System Options, then find Performance tab. They have options for Curvature generation, and level of detail.

author: ARQuattr
author_rank: Contributor
timestamp: September 24, 2013, 10:33:50 am
content: Thanks andersendr, I reviewed the Altium settings over and over and couldn't find anything that made a difference in the appearance of the model. I also changed some of the SolidWokrs settings, and although they did make the screen rendering in SolidWorks improve, they didn't change the STEP file it seems. Since when SolidWorks opens the STEP file it looks normal, I agree with you that the issue is in Altium.

author: AlfBaz
author_rank: Super Contributor
timestamp: September 24, 2013, 11:46:01 am
content: What does the dialog box that comes up after pressing the Test DirectX button in prefs->PCB Editor->Display?I cant help but think this might be a graphic card issueCurves appear fine here

author: ARQuattr
author_rank: Contributor
timestamp: September 24, 2013, 12:22:23 pm
content: I'm not sure what it tells me, but this is what the DirectX test gives (same for both monitors except of course the second shows DISPLAY2).Generally STEP bodies render beautifully so I'm not sure it's a graphics card issue. Here is another body that looks good as a whole, but if you zoom in close you can see similar tessellations. So I wonder if it's just because the radius of this part is so high - maybe it's just based on the change in angle, but how do I change that threshold?I attached the STEP file and original SLDPRT. I would be interested to hear what this STEP body looks like for others. I'm using AD10, and also wonder if AD13 would render this differently.Thanks for your input.

author: AlfBaz
author_rank: Super Contributor
timestamp: September 24, 2013, 03:21:37 pm
content: I tried your step model in AD and it looks the same as yours, all blockyI imported it into autodesk inventor and it came up nice and curved

author: free_electron
author_rank: Super Contributor
timestamp: September 24, 2013, 04:00:22 pm
content: this may have something to do with how the curve is stored ... as a curve , or as a group of short lines with varying angles.there is revisions of step and altium does not use the latest version.i have seen siilar problems with certain models. when i load them in a modeler tool ( like Rhino ) select the entity ,explode it to primitives and ask rhino to create a new 'shell' (outer surface and create the drawing using triangles then export to altium the problem goes away.i run all step models through rhino before i import them in altium. many step files are waaay too detailed and too large , or contain nested elements. in rhino i can tell the tool : create an equivalent surface and remove all the inside gunk ( the model becomes a hollow shell. ) typically this makes the step file smaller. and it loads faster in altium.plus i can change colors and other things and solve the problem having a part show up being all white. (the coloring problem is also a STEP problem. AP214 stores color information but there was a revision. altium only can handle the new revision . the older one shows up as all white.STEP format has a it of problems , just like DXf. there is too many variations and revisions and some things break between revisions.processing it through Rhino solves that. if i export AP214 from rhino altium eats it without blinking.i think for your curved surface altium creates an approximation from that large curve. and the approximation is 3 lines...if you were to change the curve yourself to an approximation with 25 lines then the render in altium would be much better.

author: ARQuattr
author_rank: Contributor
timestamp: September 24, 2013, 09:52:44 pm
content: AlfBaz, thanks for confirming that.free_electron, thanks for the suggestion. I'll give Rhino a try. What specific operation should I be looking for?