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Smooth Curves In 2d


Mike Allen

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On occasion, I have to make a 1:1 print of parts with fairly large-radius curves (over 60 inches). The model in the scene looks perfect, but when I generate a drawing view, I can never get a smooth curve. I've tried using Precise mode in the drawing, changing the part from Parasolid to ACIS - even raising the rendering surface smoothness.

 

Does anyone know what I'm doing wrong?

 

drawing_curve.gif

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I too have had success re-setting the surface smoothness of 3D models to enhance the quality of the 2d drawing, but if I recall correctly, that was in an ACIS-Draft situation (I never had to change it twice though...). Like Tom mentioned, the slider is there for play, but you can enter any number you want into the surface smoothness setting in 3D (and also like Tom, I am a fan of a setting of 200). I believe 72 is the max on the slider bar... but you can do way better than that.

 

I would also play a little with the Rastor/Vector (assuming raster would be better for your arc) settings on the printer (FIle->Print).

 

Lastly, see if the printer settings (er... printer properties) themselvs are affecting you at all.

Edited by Mike Twining
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Thanks for the suggestions!

 

I changed the surface smoothness to 200 & made a new drawing view - and it turns out that the problem was a combination of surface smoothness precise mode. When I created the view (in the default draft mode), I got a smooth arc. But when I changed the view to precise mode, the arc went to facets. Lowering the surface smoothness in the scene & updating the view in draft mode also brought the facets back.

 

It would be neat if precise mode would display a true arc on the screen & send the arc to the printer (especially send it to the printer - but, I'd also like to be able to see an accurate representation on the screen.)

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It would be neat if precise mode would display a true arc on the screen & send the arc to the printer (especially send it to the printer

17898[/snapback]

 

...agreed. I would have thought that a Parasolid model w/ a Precise view setting SHOULD have produced the same results (a nice smooth curve).

 

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I tested this with an export to an AutoCAD DWG.

 

Draft mode exports a spline & Precise mode exports a true arc (which is what I would expect.) But with my drawing view set to draft mode, when I export to DWG in precise mode, I see the view flash into facets & back to smooth. The exported file is still a true arc, but it's disconcerting to see the view change momentarily into something that appears less precise.

 

(By the way, I've tried this with both Parasolid & ACIS models & the results appear to be the same.)

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  • 2 weeks later...
Guest EricFoy

If I render with high precision, print in draft mode, but draw in precise mode, I get better results than simply printing in precise mode, no matter how precise my drawing is, or how finely it is rendered. However, I have discovered, after lengthy analysis and testing, that a precise mode draft of a roughly rendered part will usually, but not always, print as smoothly as it displays, provided that my screen resolution is set at or above my printer's DPI setting. This is only true, however, for parasolid parts. In the case of ACIS parts, the exact opposite is true, unless I invoke the ctrl-shift-B option, in which case I usually like to set my rendering at 200, switch to parasolid, re-render at 70 to 90, depending on part complexity, then switch back to ACIS. Once I do this, though, I must reset my graphics subsystem, clear the OpenGL cache, flash the BIOS and delete all cookies. This is a repeatable phenomenon, and It works every time on my AMD Athlon/64 with nVidia graphics. Once I tried this on my Gateway laptop, though. Man, you should'a been there... I mean, pixels everywhere. It took me hours to get that mess cleaned up.

Edited by EricFoy
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  • 2 weeks later...
Guest EricFoy

C'mon, guys... I really expected someone to say, "Eric, what the hell are you talking about?" or something...

 

Is my humor too dry or otherwise obtuse for y'all?

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