Problem with jagged edges in CSG solids

[odedya]

I am working on VW 2011 sp4 on various Macs but all of them seem to have the following problem that when converting a curved solid to a CSG solid by an action, such as solid subtraction, the curves on that solid become Jagged.

Once I turn the solid back to a simple extrusion the curves become smooth again.

Any clues to how I clear this up (the jagged edges remain in the solid also when I export the part to another format and open them in a different program such as rhino), so it's not a preview problem, as I first thought.

Thanks for any Ideas as how to solve this problem

[michaelk]

Can you post an example or screen shot?

Solid subtraction doesn't convert an object to a Generic Solid.

When the object is selected does the OIP think it is a Generic Solid, or a Solid Subtraction?

What rendering mode and settings?

[odedya]

Dear Michaelk,

First of all thanks for your interest.

Please have a look at both of the images:

1. before is a top view of an extruded polygon

2. after is after I have turned this extrusion to a subtracted solid file

This distortion of the shape is there in all view options.

Edited September 7, 2011 by odedya

[Kaare Baekgaard]

I think it is a 3D resolution issue (can be changed in preferences).

You can check it out by setting the openGL quality to very high and give it a render. If it looks clean, I would be right in my assumption.

[odedya]

Dear Kaare,

It isn't an openGL resolution, as it was also my first thought.

When I export these parts to other CNC/CAD programs their edges still come out jagged.

Please have a look at the image I attached that shows the same part

First as 2 separate extrudes

and the second time after I subtract one from the other and it becomes a subtracted solid, only then do it's edges become jagged.

thanks again for your assistance.

Oded

[Kaare Baekgaard]

I have seen this phenomenon again and again, Oded. And it is a resolution issue. I get it most often with very 'delicate' curves and also with long, complex extrude-along-paths.

Most export formats will cary the problem forward to the exported format, because the export function relies on 'vectorworks preferences/3D/3D conversion res' setting for its accuracy. And sometimes the setting 'very high' doesn't even cut it.

If the 3D figure is based on nurbs curves, you can fix the issue by decomposing the curves and select 'rebuild nurbs' for each curve section using more (many) control points. For complex extrude-along-paths, decompose and extrude each section of the path individualy and add-solid them afterwards.

If you need to fillet the edges later, this will sometimes fix the issue in itself.

If you use the export format IGES, all curves will be nurbs and resolution issues will not be carried forward.

If you have to use a polygon format for exports - like 3ds - you can use the split tool to cut the figure a few times before export to alleviate the problem.

If you get the problem with final quality Renderworks, then use Custom Renderworks with all settings high except 'curved geometry', which should be very high.

If you believe, that my analysis is wrong, attach the VW file to the next post.

Edited September 8, 2011 by Kaare Baekgaard