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+--- Thread: Cavities under studs (/thread-22775.html)
Cavities under studs - Oskar Flordal - 2018-03-25
I have noticed that the ldraw parts models are missing the cavities under studs that you see on a regular brick or plate (see the attached image). Is there some way I can either redfine studs.dat or some other way I can easily get those onto all the pieces in the parts database?
RE: Cavities under studs - Willy Tschager - 2018-03-25
(2018-03-25, 6:47)Oskar Flordal Wrote: I can either redfine studs.dat or some other way I can easily get those onto all the pieces in the parts database?
No and no. Beside the way that it would be an overkill in detailing to gain what: detail in areas which in 99% are hidden in a model? Please wast your time on patterns or raw LDD data http://www.digital-bricks.de/en/index.php?site=nil.
w.
RE: Cavities under studs - Oskar Flordal - 2018-03-25
(2018-03-25, 7:57)Willy Tschager Wrote:(2018-03-25, 6:47)Oskar Flordal Wrote: I can either redfine studs.dat or some other way I can easily get those onto all the pieces in the parts database?
No and no. Beside the way that it would be an overkill in detailing to gain what: detail in areas which in 99% are hidden in a model? Please wast your time on patterns or raw LDD data http://www.digital-bricks.de/en/index.php?site=nil.
w.
Thanks for the reply. I can see why this is the case for typical usage of ldraw. I am trying to train neural nets based on rendered bricks to sort bricks from photos, this works well enough for the top of the pieces but likely fails due to the lack of detail on the underside. I suppose I will have to think of some other solution.
RE: Cavities under studs - Travis Cobbs - 2018-03-26
(2018-03-25, 16:05)Oskar Flordal Wrote:(2018-03-25, 7:57)Willy Tschager Wrote: No and no. Beside the way that it would be an overkill in detailing to gain what: detail in areas which in 99% are hidden in a model? Please wast your time on patterns or raw LDD data http://www.digital-bricks.de/en/index.php?site=nil.
w.
Thanks for the reply. I can see why this is the case for typical usage of ldraw. I am trying to train neural nets based on rendered bricks to sort bricks from photos, this works well enough for the top of the pieces but likely fails due to the lack of detail on the underside. I suppose I will have to think of some other solution.
The only way to get these holes would be to create custom parts, with the holes included in the underside. The studs on top can be swapped out for lower-resolution versions, or lines, or none at all, but that is because they are placed on top of a single 4-sided polygon (quad) that models the top surface.
Poking a round hole in a surface is much more difficult, since you have to first poke a square hole in the surface (which all by itself turns 1 quad into 4 quads), and then fill in the corners with not-discs, which adds yet more triangles to make the hole circular (16 more triangles). Then you would put an inverted stud-like feature into the hole (16 more triangles and 16 more quads). Inverted, because the back side is invisible in BFC-certified parts. And you would have to create a separate surface for each size of part that the surface goes into (2x2, 2x3, 2x4, 2x6, etc.). The 2x2 one would go from 1 quad for the bottom to 20 quads and 32 triangles. If you did it in a modular way, you would make that your unit cell, and then repeat it for the other sizes.
You could make such custom parts for yourself, and after familiarizing yourself with the LDraw file format, it wouldn't really be that big of an undertaking, unless you want your computer vision to be able to recognize a whole bunch of different parts, and not just a small sub-set. But you would essentially be creating custom modified LDraw parts specifically for your computer vision project, and it's unlikely that very many people would have an interest in these parts.