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There'sa problem with part 527.dat - Printable Version

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There'sa problem with part 527.dat - Bertrand Lequy - 2021-03-26

Hi, I suppose the matter comes from hi-res primitives, but when I open this file with LDview, and when I render it with pov-ray this helmet is hollowed, and some conditionnal lines don't match the trianlgles.

Problem disappear when I uncheck the primitives substitution. 

Or is it a LDView problem I should post in Viewer's subforum ?


RE: There'sa problem with part 527.dat - Travis Cobbs - 2021-03-27

(2021-03-26, 18:00)Bertrand Lequy Wrote: Hi, I suppose the matter comes from hi-res primitives, but when I open this file with LDview, and when I render it with pov-ray this helmet is hollowed, and some conditionnal lines don't match the trianlgles.

Problem disappear when I uncheck the primitives substitution. 

Or is it a LDView problem I should post in Viewer's subforum ?

Any time a circular primitive joins a non-primitive, there is the possibility for gaps like this when the normally 16-sided circular primitives are substituted with a better approximation for a circle. (In LDView's POV exports, these become circular items in the POV code, which get rendered completely circular.) I believe that 1-16chrd.dat can be used to bridge the gaps, but 1-16chrd.dat only became official in the 2015-01 LDraw parts library update, while this part was last updated in 1021. (Actually, the file that it was moved to updated in 2012.)

In other words, I'm pretty sure that this part could be fixed, but since the fix didn't even exist when it was last created, we can't exactly complain. Note that if you set LDView's curve quality to a higher than default value, you'll see the same problem in the interactive 3D view.


RE: There'sa problem with part 527.dat - Travis Cobbs - 2021-03-27

Note that while 1-16chrd.dat will kind of solve the problem, it will still look a little strange, since there will then be a flat (horizontal) surface connecting the bottom true cone and the top pseudo-cone. To be honest, I'm not entirely sure why the top pseudo-cone isn't modeled using a cone primitive. I'm guessing it's due to the bumps. However, they're not really on a flat surface (they protrude over the edges of the triangles they are mostly on). So I don't think using a cone there would be worse.

Note: I'm not a parts author, and I am NOT intending any of this to be a criticism of the original author.


RE: There'sa problem with part 527.dat - Bertrand Lequy - 2021-03-27

(2021-03-27, 1:30)Travis Cobb Wrote: In other words, I'm pretty sure that this part could be fixed, but since the fix didn't even exist when it was last created, we can't exactly complain. Note that if you set LDView's curve quality to a higher than default value, you'll see the same problem in the interactive 3D view.

Yes, I noticed that.

Thank for your help, I'm going to try some things you pointed out.