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3d Modeling - K9
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Culvan
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PostPosted: Tue Feb 16, 2010 5:21 pm    Post subject: 3d Modeling - K9 Reply with quote

About 4 years ago I built a K9 robot. I rushed to get him completed by a convention and didn't get all the details perfect. I'd like to make some improvements. Specifically the head is a bit oversized and not quite to my liking. I've got detailed plans thanks to lespacepile's plans

I'd like to make a 3d model of the head mostly to get experience modeling. I'm pretty sure I could re-do this the way I started, by folding cardboard into the shape and coating it with fiberglass. After I've got a 3D model I'm going to CNC it out, hopefully I can make bucks and vacuum form a new, very light, head.

To give you an idea where I'm starting here's a picture of my K9.


To build him in the first place I extrapolated the lengths of all the pieces and made an "unfolded" version. This is sorta like pepakura, but done by hand.




The combination of heavy duty cardboard and multiple layers of fiberglass have made it a very strong model.


You may also notice that there are open areas on the front and back. That's because I've been trying to use this as a platform for more robotics. I've got an ultrasonic sensor and a differential IR sensor I designed. My hope was that I could make him follow a light around, but it never quite worked. I'll probably seal up the access ports and cut the proper one in the side later.

So from Lespacepile's plans, I've got scaled images for all directions. The squares are 1/2 inch:









I then created planes of the same size in Gmax and mapped the images onto them:



I've tried a few methods from this point, but they've never turned out the way I want. I was hoping to get some help from this point.

Andy
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coffeehedake
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PostPosted: Tue Feb 16, 2010 5:51 pm    Post subject: K-9 Reply with quote

Culvan wrote:
I've tried a few methods from this point, but they've never turned out the way I want. I was hoping to get some help from this point.


You got it Andy.

I *think* I'm using the same plans, however I imported the CAD files directly into Studio MAX as splines. Either way, the end results are the same: 1:1 sized guides. Typically I don't have the option of using CAD files as guides, but I prefer them when modeling.

So far I have the main part of the head meshed out. (low-poly) I'm adding details and sub-dividing to keep it as true as possible.

I'm guessing that keeping the original model as low-polygon as I can will make things easier to translate into G-Code for the CNC software, so that's the plan for now.
I'll post some pictures later tonight.
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coffeehedake
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PostPosted: Tue Feb 16, 2010 9:08 pm    Post subject: Reply with quote



Just to be sure I have my scale and grid settings appropriately modified:
(approximate)

L=15"
W=6"
H=11 1/2"

I scaled the CAD drawing down so that the each grid square matched my 3DSMAX grids (minor gridline every 1/4", major gridline every 1") assuming that the grid in the CAD drawing was 1/2" (2x2 of my MAX grids).

I then measured the Length, Width, and Height of the CAD drawing versus real world grid units.

MAX reported the real-world measurements as I have them. Am I close?
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Culvan
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PostPosted: Tue Feb 16, 2010 11:19 pm    Post subject: Reply with quote

coffeehedake wrote:
Just to be sure I have my scale and grid settings appropriately modified:
(approximate)

L=15"
W=6"
H=11 1/2"

MAX reported the real-world measurements as I have them. Am I close?


Yes, that is about a half inch smaller than my "oversized" version. I considering the cardboard thickness and fiberglass over that I think your measurements sound spot on. However getting the exact same measurements is very difficult since the orientation of the picture is somewhat arbitrary compared to the real object.

Andy
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coffeehedake
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PostPosted: Wed Feb 17, 2010 1:45 am    Post subject: PM's Reply with quote

Having some issues sending you PMs. *shrug*

I sent you a reply, and I'm guessing it just didn't go through, as it's sitting in my outbox...


Anyway... got a little done on the snout:



If you *do* happen to get my PM, disregard the bits about K-9, I wrote that before you posted this thread. Smile

Also, I had gotten about 1/2 way through modeling K-9's head, and scrapped the model, to start over, with a different method. At first I took a shot at spline modeling, but I didn't like how the surface modifier was mucking around with things. I'm just going to mesh the whole thing out from scratch which should give more control.

Let me know if you already see anything that needs tweaking. The only mesh in the above picture is the contiguous pink blob. The rest are just the CAD files, which I recolored just so it was easier to tell them apart.
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jegner
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PostPosted: Wed Feb 17, 2010 9:37 am    Post subject: Reply with quote

Very cool! Thanks for sharing.
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Culvan
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PostPosted: Fri Feb 19, 2010 9:24 pm    Post subject: Re: PM's Reply with quote

coffeehedake wrote:

Anyway... got a little done on the snout:


Looking good. However what you have looks like there is a hole in the middle of the piece where teh nose laser housing comes to the flat section. That should smoothly blend into the flat surface.

What do you call this modeling technique. It looks like you are working with squares (quads?) I can't tell for sure, but it looks like they get a lot denser on the curved section of the laser housing. Did you make this as two parts then merge them somehow or did you make one and modify it.

Thanks for running through this.

Andy
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coffeehedake
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PostPosted: Sat Feb 20, 2010 8:59 pm    Post subject: Reply with quote

Culvan wrote:
However what you have looks like there is a hole in the middle of the piece


Yep, I didn't seal the plane, trying to figure out exactly how it should round it self off.

Culvan wrote:
What do you call this modeling technique. It looks like you are working with squares (quads?)


There's a few techniques being used here.
I started the whole piece you see with a single square plane primitive in MAX.

Usually starting this way is considered 'box modeling.' You can also use a cube or cylinder, depending on what more closely resembles the object you are modeling.

I wrote up a PDF of the instructions here.

Culvan wrote:
It looks like you are working with squares (quads?)

Exactly right. Usually, the best practice is to make quads with as few isolated triangles as possible. MAX and game engines typically handle quads better than quads with triangles. For our purposes, I don't know if this matters, but the habit stuck. Wink



Culvan wrote:
I can't tell for sure, but it looks like they get a lot denser on the curved section of the laser housing.


Also spot on again. They get denser on the curved sections, because we need more vertices to work with to keep the curve accurate.

Culvan wrote:
Did you make this as two parts then merge them somehow or did you make one and modify it.


I actually sliced the whole model in half, since it's functionally identical on one half of the head to the other. You can do this with humanoid faces too, but you need to go back and change tiny details to make things accurate. No human face is actually the same on both sides. Machined parts are (robots, helmets, etc) as long as they are made correctly.

Stormie buckets are not symmetrical (at least not the stunt helmets) neither are Boba's helmets. But anyway... I think that works for this particular model. (Up to you though)

This is kind of just a primer guide, if you have any questions, or if something is not clear, I can add it in to the PDF and update it. It ends sort of abruptly but at least it gets you started on the concept. (It's my weekend with my boys, and they are both sick, one with an ear infection, so I was writing this in between watching them)

Let me know what you think! Thanks man.
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coffeehedake
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PostPosted: Sun Feb 21, 2010 11:14 pm    Post subject: Progress Report Reply with quote

Made some headway...

"ba-dum-tish"



Got most of the top of the head done, sealed the hole in the nose, just have to do some more sub-dividing on the top, and add in the sockets for the ears. I've left room exactly where the sockets go, so that I can extrude them later. I just hope this method doesn't come back to bite me.
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coffeehedake
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PostPosted: Tue Mar 09, 2010 7:22 pm    Post subject: Reply with quote

Just a small update, and a quick question...

I didn't want you to think I forgot about you, and I am still working on the model in between buying parts for the CNC machine, watching the kids, doing research, etc...



These round parts, look to me to be screws or rivets, but I didn't see them on the source photos of the screen-used prop. (I may have overlooked it, and my good source pictures are on my other computer somewhere)

Are they part of the head, something that I should model in, or is that something you'd rather add onto the finished surface after primer and paint?

I can go either way there, but I need to plan accordingly for subdividing the adjacent quads so that the 'round' edges will blend properly.

I've started on the side of the head, and it's coming along slowly, but cleanly.



I've also decided to throw a mesh-smooth modifier over the whole joined surface when it's done, to add additional subdivision, detail, and smoothness. Considering I'm used to dealing with low-polygon triangle budgets (when I started modeling in the Quake I days, 3000 triangles was a hefty model) this will still be a low-polygon model even with the iterations cranked way up, by today's standards, but will offer quite a bit of detail for the end product.
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coffeehedake
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PostPosted: Tue Mar 09, 2010 10:37 pm    Post subject: Reply with quote

Here's another update, I don't want to get annoying (too late!)

I added some mesh to the sides.... but it's badly in need of additional subdivision, as you can see at the back of the head. No problem, just haven't gotten there yet. To keep things tightly designed, I've been working each part (Top of snout, top of head, side of head, side of snout, etc) individually, and stealing pieces from other parts (mostly edges) that wrap around the model so that the seams line up.
This will make it easier to weld the vertices together later. I'd rather keep the welding to a minimum; as the model gets more complex, it gets easier and easier to lose track of what vertices needs to be welded.



Let me know what you think.

The smoothing is off on that part I have pointed out because the two pieces aren't welded (and actually are two separate meshes for right now) but I've already corrected that in the version I'm working on right now... no updated screenshot to show that, but not that big of a deal.
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Culvan
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PostPosted: Thu Mar 11, 2010 5:54 am    Post subject: Reply with quote

That's looking great! The round things are screws/rivets. I can add them as actual screws or rivets later.

I'm not sure what's going on with the shading, but something looks odd about the area on the side of the nose. The front is very bright then it very quickly turns dark. That leads me to believe there is something of a corner there. It could be a trick of the rendering, but I had expected a more gradual shift. Is that whole line a separation of faces that need to be joined?

The sides are the reason I never was happy about my own models. I couldn't get the curve right. Your's looks perfect at the top.

If my eventual goal is to CNC this, then it would be useful for the interior to be solid. Is there a way of joining the sides up so that it is not hollow? If not it's no big deal, I'm pretty sure I've got some software that can handle it.

Andy
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coffeehedake
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PostPosted: Thu Mar 11, 2010 7:35 am    Post subject: Reply with quote

Here's a little update, hard to tell that I really did anything, except that the seams are all welded, and all of the parts are now one big piece of mesh.



Culvan wrote:
That leads me to believe there is something of a corner there. It could be a trick of the rendering, but I had expected a more gradual shift


Hmm... I may need to revisit that. Should the side of the nose have sort of a channel around it, or simply round off to a flat surface?

Here's a better, and updated shot of the nose, perhaps it will help to identify the issue...



Culvan wrote:
Is there a way of joining the sides up so that it is not hollow?


Sort of... when it's all done there will be no holes to the inside, but mesh is always hollow. I can also extrude the interior, or cap it off.

We'll work on that part after it's all done, but if you decide that the way you'd like to mill it is in halves, I can cap it off exactly in the middle, so that the software isn't confused about the other side.
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coffeehedake
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PostPosted: Sun Mar 14, 2010 8:05 pm    Post subject: Reply with quote

Ok, I've got an update, and some more questions.

Here's the source pic:


And here's the latest version of the model:


Questions...

1) I noticed that the top of the snout is rounded off where the seams meet. As well as the seam on the top of the head where it meets the sides. Is this right?
2) It would appear that the nose is capped at the end... the CAD drawings don't reflect this, they show a thin edge, with a hole. I'm guessing it should be capped, is that right?
3) Would it be easier if I finished the model together, and then separated the pieces, so that it could be assembled like the original, or do you want the whole head to be one piece? If I separate them, I can add thickness to the pieces so that each piece would have a top and bottom (as well as sides).
4) How do you want me to handle the eyes, the bars across them, and the laser in the nose?
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Culvan
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PostPosted: Mon Mar 15, 2010 8:58 am    Post subject: Reply with quote

coffeehedake wrote:

Questions...

1) I noticed that the top of the snout is rounded off where the seams meet. As well as the seam on the top of the head where it meets the sides. Is this right?

Yeah, I suppose that's true. However I've seen a number of home built models where the edges are sharp. They still look good. Your eye for detail is correct on the real prop they should be rounded.

Quote:
2) It would appear that the nose is capped at the end... the CAD drawings don't reflect this, they show a thin edge, with a hole. I'm guessing it should be capped, is that right?

I wasn't able to see what you had done in the "mouth" area before. Yes, it should be capped, there is a hole for the nose laser though. There is also a thin rectangular hole for a mouth, in the TV show a strip of paper like a printout would come out of there.

Quote:
3) Would it be easier if I finished the model together, and then separated the pieces, so that it could be assembled like the original, or do you want the whole head to be one piece? If I separate them, I can add thickness to the pieces so that each piece would have a top and bottom (as well as sides).

An interesting question. The goal is to get a finished object that looks like the assembled original. The ability to dissasemble it is unimportant, unless it makes the completed unit look better. So, I guess the answer is do what's easier. When I get around to cutting this thing, it could be useful to cut it in pieces because it is too big for a single shot on my machine. If it doesn't add too much complexity then separate pieces does have some advantages, but I haven't thought all the way through the manufacturing yet.

Quote:
4) How do you want me to handle the eyes, the bars across them, and the laser in the nose?

Both of those are separate parts. The nose laser is supposed to be actuated so it extends. The eye slats are a red tinted acrylic. The slats would be best as a separate (or detatchable) piece. The laser could be left off entirely or added as another removable part.

Andy
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