Displacement modifier, surface control?

Displacement modifier, surface control?

I have a disc model, lightly spherified and with a displacement image applied, to represent the top of a clothing button (or medallion). To create the balance of the button base and to assure the right thickness for 3D printing, I modeled a capsule, dissected it leaving the top and part of the side to reach the appropriate depth, reversed the normals and sized it to fit inside the disc.

I covered the outer ring of the disc (which has a displacement modifier) a tiny bit, sucked the capsule construction into the disc group as an adopted child and bridged the gap between the two groups to create the entire button base (without the attachment shank in the bottom middle).

As soon as I activate the displacement modifier, it applies to the entire model and the smooth sides and bottom of the model become distorted/ragged. How do I retain the smooth surfaces of the adopted capsule group and have the displacement apply only to the original disc (button/medallion) top?

Looking for the lower side toward the edge of the disc, the side and the bottom of the model, we now have this appearance:

At least when it comes to export the mesh for 3d printing you will need to make it editable - the front only - select the outer edge loop - cover and drag back for thickness - fill hole - inner extrude - collapse. For example.
Be aware of a giant file about ca 60MB uncompressed geometry.

Cheers
Frank

Frank
I had returned to your original instructions and tried that approach, but as soon as a 'covered(extruded)' the edge ring the side was immediately distorted by the displacement. As I continued to build the rest of the model shell, the displacement continued to exhibit. That's why I thought if I constructed the balance of the model from a separate mesh, the displacement would not alter the surface, but as soon as I joined the two models to be able to bridge and create one, the displacement grew.

Can I limit the displacement to the disc top only? Modo has a weight tool that can serve as a mask, and the UV mapping also controls the displacement, but, as we both know, they don't model the mesh until you 'freeze' it, which creates humongous meshes that have open edges, holes and more. NOT nearly as good as C3D.

I did one early model and added some black to the edges of the image, but that also moved the rope-styled trim inward from the edge of the top. Perhaps I need a 3D rope trim in circles and use the displacement map only for the names, stars and reindeer? Is there a prebuilt braid or rope design I could incorporate? That would take the edge distortion away.

Whew
OK, it appears my solution, which I don't know is the only solution, was to revise the displacement image and leave a very small, plain space at the very edge, allowing me to cover the edge loop and remain flat. I then continued to cover, adding a couple of ring cuts for shaping and layer thickness and made the fill hole as tiny as possible since it required the collapse to flatten it.

I have added the shank, simply by piercing the model. I hope that works.
The file is humongous on output, some 173mb as an STL, but netFabb immediately pronounced it a valid mesh, with no flaws. WOW. Saved as STL within NetFabb and file dropped to 49mb.

Here's the result. I'd still like to learn if there was a way to smooth the sides without the image manipulation and whether simply punching the shank into the mesh was an acceptable solution for creating the model.
Thanks....Santa Stephen

What works for the shank might work then for the rim?
Here´s a simple Metaball/Chain-Creator setup which you might find useful.
BTW: as you already noticed the Displacement-modifier just works per object.

Cheers
Frank

Thanks Frank, I'll try the chain to see if I like the actual chain versus a displacement distortion of a rope-like image.

So, it's OK to punch a hole into a mesh to 'add' another object to a model?
No need to weld points or merge?

I don't think I could use the same technique for the bottom and sides as the roughness of the displaced edge makes for waviness that leaves gaps and I can't thicken the surface like the Modo thicken command (a neat device, BTW).

I'm loving C3D, especially with your expert guidance. Thanks for participating in the forum and sharing your expertise. What an asset for Martin.

SantaStephen said:

T
So, it's OK to punch a hole into a mesh to 'add' another object to a model?
No need to weld points or merge?

Click to expand...

Modeling wise there´s no limit - but for 3d-printiing I´m not sure. From what I read here and there it has to be "watertight" - but when Boolean operations come into play you will instantly loose control over your mesh - especially with highres meshes and you might need other tools to check the surface for errors.

Cheers
Frank

Thanks again, Frank
I used both Meshlab and netFabb to check the model and both said - good to go. I resaved the STL with netFabb and it shrank considerably. I just uploaded it to Shapeways and first pass is a "Success, your model passed out first series of tests." I'm ordering a print for delivery by 2/16 to see if it meets the foundry needs.
Santa Stephen

Sounds great.

Have a nice weekend.

Cheers
Frank

Hi All,

It would be quite interesting how the printer manages to print that thing. I mean in terms of support geometry and such. It seems to be a quite a challenge to get it done, given the tiny base with hole, concave underside, etc.

Perhaps you can post a photo documenting the state it arrives.

BTW excellent model ... Very well done.

Regards.

Caustics said:

It would be quite interesting how the printer manages to print that thing. I mean in terms of support geometry and such. It seems to be a quite a challenge to get it done, given the tiny base with hole, concave underside, etc.

Click to expand...

Hi,

That's not a problem at all with Shapeways as they use SLA where support geometries are not needed.