Jump to content
Product Design Forums

Treasurebox
Sign in to follow this  
Guest retrospec

What Is Your Favorite 3d Modeling Method?

Recommended Posts

Guest retrospec

opps my poll didn't show up...

 

1) parametric solids and surfaces (Solidworks, Pro-E, Inventor, CATIA)

 

2) Polygon (3ds Max, Maya, Lightwave...)

 

3) Nurbs (Rhino, AliasStudio, Maya)

 

4) Sculpting (Zbrush, Mudbox)

Share this post


Link to post
Share on other sites
Guest retrospec
You missed one......get somebody else to do it and go home earlier :P

 

yea I should try that one, seems pretty effective

Share this post


Link to post
Share on other sites
Guest IvanRD

Depends on what end result is required. You are comparing apples and oranges. Might as well throw in clay modeling in there as well then.

 

If you are only using the 3D models for visualisation purposes, then it really comes down to personal preference (ie. which programs you are most comfortable with and the tool set and shape required. eg. organic model ) For taking your concepts through to manufacturing though, you mostly have to stick with number 1 and perhaps combination of 1 and 3.

 

Ciao,

Ivan

Share this post


Link to post
Share on other sites
Guest Grant Howarth

2 for visualisations + presentation purposes (to develop and sell the idea).

 

1 for final model

Share this post


Link to post
Share on other sites

Even though I ain't that good at it, and it takes a lot of skill, I have to go for polygon. Nothing compares to actually manipulating vertices, edges and faces directly - right there - on your 3D model.

 

Sculpting is a little to freeflowing, I'd love to take a real clay modeling class though and then maybe get into "digital clay" software like mudbox and sensable's freeform modeling, for like implants and fake dentures and stuff - that stuff is slick!

Share this post


Link to post
Share on other sites
Even though I ain't that good at it, and it takes a lot of skill, I have to go for polygon. Nothing compares to actually manipulating vertices, edges and faces directly - right there - on your 3D model.

 

Editing Nurbs Surfaces is basically the same process. Pulling CV's, Isoparms, etc.

 

The difference is polygons are only useful for visualization. Once you learn to master pulling CV's you can use those skills to bring your designs all the way to production quality surfaces.

 

Either way my workflow is 3 (Modelling)->1 (Production and assembly)->2 Rendering.

Share this post


Link to post
Share on other sites
Guest retrospec
Even though I ain't that good at it, and it takes a lot of skill, I have to go for polygon. Nothing compares to actually manipulating vertices, edges and faces directly - right there - on your 3D model.

 

Editing Nurbs Surfaces is basically the same process. Pulling CV's, Isoparms, etc.

 

The difference is polygons are only useful for visualization. Once you learn to master pulling CV's you can use those skills to bring your designs all the way to production quality surfaces.

 

Either way my workflow is 3 (Modelling)->1 (Production and assembly)->2 Rendering.

 

you perfer nurbs over parametric solids? Which program do you use? I'm assuming it's either Alias or Rhino, don't you find it difficult without a history tree?

Share this post


Link to post
Share on other sites
don't you find it difficult without a history tree?

 

A history tree isn't always an additive value, it can often be a burden.

Rhino can record history if you want it to for a certain operation, and solidThinking has full history capabilities.

 

Cyber, as for your statement - I didn't really quite think of it that way before, but to get the best smoothness isn't it always working OFF your model and tweaking its curves that you then trimmed or something? Basically making the whole process quite off the model unlike polygons (excluding subdivision surfaces)

Share this post


Link to post
Share on other sites
Guest under-dog
don't you find it difficult without a history tree?

 

A history tree isn't always an additive value, it can often be a burden.

Rhino can record history if you want it to for a certain operation, and solidThinking has full history capabilities.

 

Cyber, as for your statement - I didn't really quite think of it that way before, but to get the best smoothness isn't it always working OFF your model and tweaking its curves that you then trimmed or something? Basically making the whole process quite off the model unlike polygons (excluding subdivision surfaces)

 

IMHO

 

I find the history tree can be a burdon for doing quick iterations of quick initial comcepts. However once this initial concept is layed out parametrics is the way to go. We get files in from vendors and design firms all the time that are made in rhino or something similar and have obviosly(by studying the geometry), been patched and knitted together as well as free form manipulated. This is a fast way to rough out form but has severe downsides for true engineered files. We usually use them as a "go by" at best. They may in some instances have been madeon SW or something similar but he person obviosly did not know what they were doing. You can have a tool that is specifically designed for a job and if the person using it has no idea what they are doing the job will still be a total mess.

 

Freeform nurbs for initial concept

Parametrics for advanced modelling and Engineering files

 

Here is why:

 

Freeform Nurbs-

 

Pros-

-fast

-easy

-no feature overhead to trip over or unravel as you make changes(geometry is basically WYSIWYG)

 

Cons-

 

-Accuaracy

-pureness of form and geometry

-lack of ability to make calculatable and quantifiable manipulations. Steretching, pulling and other forms of free form nurbs manipulations ,while may give you something that "look" like you want at first glance can become absolute crap geometry at second glance. Often times when we get these files they are just twisty doughy surface that have little or no value for making a mold, defining datums,etc.. In most situations they can create far more problems than the benefits of a "quick build"....if you attempt to bring them to the next level and use them for engineering and mold builds.

 

**good for quick initial iterations of 3D concepts**

 

Parametrics-

 

Pros-

-Explicit control over every aspect of the build and the ability to make changes at the level thae features were origionally crated at. "You make a 3mm diameter cylinder and decide much later you wanted it 4mm you dont have to scale or do something that is unpredictable to make the change"...or possibly undoable and calls for a total rebuild of features.

-Accuracy

-More control over establishing quantefiable stable geometry.

 

Cons-

Takes a bit more work to establish more complex geometry especially in a way that is stable.

Can be finicky and instable when making changes especially major changes. This is linked to a few variables though:

 

1) how good the user is and the strategy they use to develope the files

2) how complex the geometry is

3)how severe the changes are

 

**Better for controlled accurate and quality engineering files**

Share this post


Link to post
Share on other sites
you perfer nurbs over parametric solids? Which program do you use? I'm assuming it's either Alias or Rhino, don't you find it difficult without a history tree?

 

I use Alias and Pro E. Concept design is all done in Alias, and then those surfaces are brought into Pro E for transferring to engineering, creating solids and other features for prototyping, etc. I get by with my construction history, and I don't know how I would live without the surface evaluation tools that Alias offers at a flick of my mouse (marking menus).

 

don't you find it difficult without a history tree?

 

A history tree isn't always an additive value, it can often be a burden.

Rhino can record history if you want it to for a certain operation, and solidThinking has full history capabilities.

 

Cyber, as for your statement - I didn't really quite think of it that way before, but to get the best smoothness isn't it always working OFF your model and tweaking its curves that you then trimmed or something? Basically making the whole process quite off the model unlike polygons (excluding subdivision surfaces)

 

Polys are great for getting the shape, but not the surface. If you're designing something that is just going to be shown on screen, this doesn't realy matter. You can get the outline to look like what you want, then fill in the inside with something pretty close. But once you actually bring that into the real world - especially for anything that fits in the hand, on the body, or is highly reflective (a car) suddenly that surface quality becomes much more important.

 

The "Tweaking curves" process of working with NURBS is very crude. You realy want to use curves just to generate your base surfaces, then modify those by hand as necessary. The curves give you the structure, but the ability to modify that by pulling CV's is how you evolve the form precisely and accurately. Solid modelling is generally done by defining curves of all of your important cross sections, then letting the computer fill in the patches. When you control the patches directly you have a lot more power.

Share this post


Link to post
Share on other sites
This is a fast way to rough out form but has severe downsides for true engineered files. We usually use them as a "go by" at best. They may in some instances have been madeon SW or something similar but he person obviosly did not know what they were doing. You can have a tool that is specifically designed for a job and if the person using it has no idea what they are doing the job will still be a total mess.

 

Freeform nurbs for initial concept

Parametrics for advanced modelling and Engineering files

 

Here is why:

 

Freeform Nurbs-

 

Pros-

-fast

-easy

-no feature overhead to trip over or unravel as you make changes(geometry is basically WYSIWYG)

 

Cons-

 

-Accuaracy

-pureness of form and geometry

-lack of ability to make calculatable and quantifiable manipulations. Steretching, pulling and other forms of free form nurbs manipulations ,while may give you something that "look" like you want at first glance can become absolute crap geometry at second glance. Often times when we get these files they are just twisty doughy surface that have little or no value for making a mold, defining datums,etc.. In most situations they can create far more problems than the benefits of a "quick build"....if you attempt to bring them to the next level and use them for engineering and mold builds.

 

This is a flaw of an inexperienced designer, not a flaw of the tools or technology. From Alias I can deliver 100% accurate, Class-A quality surfaces that are used directly in production without ANY modification from engineering or tooling. The engineers can go in, offset my surfaces, build all of the internal product structure, and with the use of Pro-E can quickly replace patches in areas that have been modified downstream. If done correctly - the entire model will be able to regenerate itself based on the new surfaces that have been merged in. It's painfully complex, but when it works it's pretty fantastic.

 

Sloppy surfaces come from sloppy designers, not from the tool. Many times our engineers will have us build the geometry used to cut reveals, cores, etc - because we can do it faster and cleaner in Alias than they could in ProE.

Share this post


Link to post
Share on other sites
Guest under-dog
This is a fast way to rough out form but has severe downsides for true engineered files. We usually use them as a "go by" at best. They may in some instances have been madeon SW or something similar but he person obviosly did not know what they were doing. You can have a tool that is specifically designed for a job and if the person using it has no idea what they are doing the job will still be a total mess.

 

Freeform nurbs for initial concept

Parametrics for advanced modelling and Engineering files

 

Here is why:

 

Freeform Nurbs-

 

Pros-

-fast

-easy

-no feature overhead to trip over or unravel as you make changes(geometry is basically WYSIWYG)

 

Cons-

 

-Accuaracy

-pureness of form and geometry

-lack of ability to make calculatable and quantifiable manipulations. Steretching, pulling and other forms of free form nurbs manipulations ,while may give you something that "look" like you want at first glance can become absolute crap geometry at second glance. Often times when we get these files they are just twisty doughy surface that have little or no value for making a mold, defining datums,etc.. In most situations they can create far more problems than the benefits of a "quick build"....if you attempt to bring them to the next level and use them for engineering and mold builds.

 

This is a flaw of an inexperienced designer, not a flaw of the tools or technology. From Alias I can deliver 100% accurate, Class-A quality surfaces that are used directly in production without ANY modification from engineering or tooling. The engineers can go in, offset my surfaces, build all of the internal product structure, and with the use of Pro-E can quickly replace patches in areas that have been modified downstream. If done correctly - the entire model will be able to regenerate itself based on the new surfaces that have been merged in. It's painfully complex, but when it works it's pretty fantastic.

 

Sloppy surfaces come from sloppy designers, not from the tool. Many times our engineers will have us build the geometry used to cut reveals, cores, etc - because we can do it faster and cleaner in Alias than they could in ProE.

 

 

 

 

Freeform opens the window for these inexperianced deigners though to really do some damage. It is not an issue if you understand what you are looking at and undestand the actual value of a "concept file" as well as its limitations. The issue arises when someone who doesnt know makes a rash judgement and says "all we need to do is tweak it a little right?"

 

The untrained eye or brain just sees something that appears to be correct. They dont get it. They dont and in most cases cant analyse or distinguish good from bad.

 

 

As far as the method you described: Basically you are talking about generating the outside shell and then the engineers can core things out and add the internal features they need. I guess I see this as dependant on a few things for success:

 

1) The type and complexity of product/geometry

2) Will there need to be any major changes to that outside shell? If so you may find yourself painted into a corner and completely rebuilding if major change arrive. I am talking beyond just patching in or repairing a few surfaces or addind a new piece of geometry. What if the outer shell needs to be enlarged overall to fit components, etc.

 

 

It can be far easier to set up certain relationships(especially stable ones) at a more fundimental level of the models developement than trying to extract surfaces off of a fully fleshed out form and then untrim, extend and trim, etc etc.

 

 

More often than not it is easier to start from the ground up using the concept as a go by than to try an beat and orphaned solid to death to get what you need.

 

 

But then again I guess it depends on the type of product, the geometry involved, the manufacturing process, where the tooling will be done and where it will be manufactured.

 

An offshore tool they dont care if the surfaces, parting lines, and tooling in general ar a bit screwed up. They dont care if they have to fudge the mold or have someone hand stripping a part and then scraping parting lines and maybe bead blasting the part. If its bad enough they paint it. They dont care if the tool has hand inserts and has to be in constanct maintenance.

 

I know here when we make tooling to run here in the US the tool must and will run 24-7 without a hitch. The parts must drop out or be picked off the press ready for assembly. No hand stripping or finishing of any kind. Aside from tampo printing, coating etc. But even that is automated. And very little but predictable maintenance.

 

And trust me when I say that bad files can absolutely have an impact on this.

 

I am not saying that you cannot get good files out of freeform programs. But freeform methods while fast and flexible can and I am saying can create issues whether subtle and hard to initially percieve or blatent. Not a given but can. It definately opens up the possibilities for someone who doesnt know what they are doing to create issues if the intent is an engineering file.

 

 

 

knit and patch surfacing is not by any means the most simple and stable meand to an end.

 

 

We have gotten a bit off track here. Each form of modelling has its place and its purpose was my origional point.

Share this post


Link to post
Share on other sites
Guest retrospec

so nurbs program like alias and rhino can actually be accurate enough to provide parts for milling and other operations and do not need a CAD program like solidworks to convert and add details if the user is good enough, is that correct?

Share this post


Link to post
Share on other sites

Please sign in to comment

You will be able to leave a comment after signing in



Sign In Now
Sign in to follow this  

×

Important Information

By using this site, you agree to our Terms of Use.