Hi Jan,

> I just wan't to point out that I do not expect any of my ideas to
> be implemented - even though I like to defend them ;)

They may not get implemented as a _default_ setup, but I can certainly see them being implemented as a plug-in that you could set up on your particular installation of MoI to help you get some of your particular needed tasks to get done.

Hopefully the Golden rectangle snap that you've already just set up has been a step towards that already?

Would a golden-ratio snap on a line still be useful as a separate thing from the golden rectangle, or does that new golden rectangle snap handle what you need already?


> I bring this up because I use to work with some of those 'creative people'
> and at least those would have stopped digging into any more detail if there
> wasn't a simple colored button to push... ;)

Ok, but it's not like MoI is a program where you just push a big button and it reads your mind and pops out a finished model automatically - just doing the core function of the program of constructing 3D models is difficult enough as it (I mean I've tried to make things simplified when possible, but still there's definitely learning involved) is that if setting up a keyboard shortcut is going to be totally beyond someone's ability to learn how is it that they're going to stick with things long enough to do the stuff that's more complicated than that?

However having said all that I do definitely want to overhaul the plug-in and shortcuts system to make them more streamlined. They just have not got a whole lot of attention so far because they tend to be things you set up just once or very infrequently and not really things you need to mess with on a daily basis, so they just have not been a big target quite yet.

- Michael

Hi Jan,

> Another idea for MoI, by stressing nature again, could be based on
> 'minimal surfaces' as an optional style for the 'loft' tool.

This is another interesting idea, but it's unfortunately quite difficult to implement well with the structure of NURBS surfaces - that type of surface tends to be easier to calculate on a set of triangular meshed nodes and the method of solving it I think typically uses an iteration approach that slightly repositions the triangle vertices during the calculation process.

The way NURBS surfaces work is fairly different to that particular kind of process and so it would be quite difficult to make a NURBS type version of a minimal surface construction I think.

There is no built in support for minimal surface creation in the geometry kernel that MoI uses for a lot of NURBS calculations, so it would require a considerable amount of specialized development to even try it.

In the future I do want to work on a type of surfacing method called an "n-sided patch" which is a surface fitting technique that has a few similar elements to it though.

- Michael

Hi Michael,

the golden rectangle snap is working like a charm and does
serve my needs for it just fine It reduces the time I spend
before to construct or calculate that point manually, so
thanks again for the script and the lesson for its implementation.

I do still consider a seperate golden snap function as beeing very
interesting and a plug-in for that would be just as fine as it was inbuild.
But if it is just me and maybe just a view others it may not be worth
enough the effort of programming it.

Maybe time and a view more comments on this topic from other
users and what they may think about this will help to verify this idea.

If there is no chorus demanding there is no reason to bother.

Jan

Minimal surfaces

Somehow I knew this was going to be difficult, because whatever nature does incidentally becomes quite tricky
to get it mimicked ... ;)

Without beeing a NURBS expert at all and just for the reason of interest, if such calculations for minimal surfaces
are realized in triangular meshed nodes, wouldn't it be possible to use such nodes as an intermediate result and
acting as a control mesh by which a final NURBS surface could approximate itself to a minimal surface?

... wow, by chance I just stumbled into this plug-in for sketchup called 'Soap Skin & Bubble' which seems to be
based on the triangular meshed nodes you mentioned. The plug-in and it's functionality is shown in this video:

http://www.youtube.com/watch?v=mcOrlX5wgLE

Actually this plugin does what I was thinking of and a review of it can be found here:

http://sketchuppluginreviews.com/2010/02/02/soap-skin-bubble-tool-google-sketchup-review/

So, if I am not mistaken, the math behind this minimal surface model is done, the plug-in is free of charge,
what could mean, that the author may happily give an inside view to his work to others...

And if a NURBS surfaces could be controlled by a polygon mesh ... - Voilà! ...

> ... so it would require a considerable amount of specialized development to even try it.

... this quote may get reduced to a fraction of its meaning... ;)

By the way, the author of that plug-in is German so let me know if you need any assistance in that language... ;)

Jan

Hi Jan, re: Minimal surface - unfortunately no it's not easy for a NURBS surface to be adapted to any general polygon mesh because a polygon mesh has arbitrary topology, while a NURBS surface requires a regular rectangular control point layout, meaning it has to have a grid of control points forming rows and columns and not just a big mass of arbitrarily connected points like a bunch of triangles can be.

- Michael

Hi Jan,

> I do still consider a seperate golden snap function as beeing very
> interesting and a plug-in for that would be just as fine as it was inbuild.
> But if it is just me and maybe just a view others it may not be worth
> enough the effort of programming it.

Tomorrow I'll take a look and see if I can cook up something to help with the line-proportion type method.

- Michael

Hi Michael,

ok, here it comes:

I installed Sketchup, the Soap Skin & Bubble plug-in, killed myself while trying to draw some simple curves in Sketchup, and did a sweep in MoI instead,


MoI: Set of curves

exported formats in between several programs to finally end up with a frame for the plug-in to do it's magic ... and it did!


Sketchup + Soap Skin & Bubble plug-in : The mesh and its formation towards a minimal surface was done automatically by the plugin

The resulting surface was then again exported several times to get a final render of it:


KeyShot: Quick render

The plug-in itself seems to work with quadrangles, at least visually. The triangulation seen in the render happened - also visually - after exporting the file.

But as I said I have no clue at all about the secrets of NURBS programming and therefore belief blind in what you say.

Maybe I can find a way to somehow re-model the surface back to MoI to go further from there.

Jan

From a commercial point of view, the "golden" formulas are used in garden design as they help naturalise views and create a more peaceful and pleasing result to the eye.

Martin

About Soap Skin and Bubble and Sketchup there is a better script!
Ferrari (free) http://forums.sketchucation.com/viewtopic.php?f=323&t=32380&p=286311 (scroll the page 6th post )

Hi Pilou,

looks promising as Ferrari seems to work even in between two closed profile curves to which
I could not manage to talk 'Soap Skin & Bubble' into so far...

Here is a direct link to download this plug-in in V 1.1 without the need of registration:
http://modelisation.nancy.archi.fr/rld/download.php?file=FerrariSketchV1.1.zip

Unfortunately it runs on Windows only, so for the Mac users among us it looks like another
installation on 'Parallels' to get a try out.

Thanks for this information!

Jan

@Pilou

Unfortunately the Ferrari plugin as well as sketchup did not work stable for me
on more complex shapes on a parallels windows emulation on MacOS Lion.

Simple shapes and reduced calculation precision and grid resolution works fine
and is really nice to play arround with.

I wonder if there are more stable solutions of such bubble skin tools available,
maybe as a stand alond program with good export options...

Jan

Hi Jan - re: minimal surface,

> The plug-in itself seems to work with quadrangles, at least visually. The triangulation seen
> in the render happened - also visually - after exporting the file.

From what you showed there it does seem to use some amount of quads but not 100% only quads - look near the boundaries of the surface and you can see a lot of them are sliced off, those ones are not quads but instead n-gons.

So you don't have a totally restricted "all quad" topology there - because of that there isn't really an automatic way to transfer from a generalized polygon mesh like that to the totally uniform MxN grid of points that a NURBS surface requires for its control polygon net.


> Maybe I can find a way to somehow re-model the surface back to MoI
> to go further from there.

If you can convert it to OBJ format, you could then use the OBJ to 3DM wireframe converter here:
http://moi3d.com/resources#Obj23dmWireframe_converter

That will convert the edges of that polygon mesh data into lines in a 3DM file, and then that 3DM file can be loaded into MoI, and you'll then have the wireframe of that model which you could use to as a snapping guide when drawing some new curves.

But just in general polygon mesh geometry like you have generated there is a pretty different form of data than NURBS geometry.

Polygon mesh data is made up of a lot of little facet pieces. NURBS geometry is made up of larger smooth spline surfaces.

It is possible to convert a broad smooth NURBS surface into polygons by dicing the surface up into little flat pieces - MoI will do that for you if you export to a polygon mesh format like OBJ, LWO, STL, SKP, ... Think of this step as similar to how you can take apples and smash them up into little bits to make applesauce.

But if you are starting with already diced up data (the faceted polygon mesh type data) and want to convert it back into big NURBS surfaces, that's basically the equivalent of wanting to start with applesauce and trying to reconstruct full apples back from the smashed up applesauce - a difficult task...

- Michael

Back to the golden ratio, why the golden rectangle cant be a default snap? I dont think it would be confusing. The cline golden snap would be very useful too!

Hi ed,

> Back to the golden ratio, why the golden rectangle cant be a default snap?

Check out here for an answer:
http://moi3d.com/forum/index.php?webtag=MOI&msg=3628.285

It could become one if it gets asked about frequently enough. So far it's only been requested or mentioned quite rarely, and things that are only needed rarely by a small number of people are not great to have as defaults.

- Michael

Hi Michael,

your visualized example now got me hungry for hash browns... ;)

I understand your point in those irreversible restrictions in between the NURBS and polygon worlds,
even though I would go to freeze back the sauce in its original apple shape in this world... ;)

By searching the internet on this topic so far I could only find the NURBS -> Polygon direction and not
the other way around.

Thank you for the link to the converter which I will try out on those bubble skin surfaces from sketchup
for remodelling in MoI.

Jan

Hi Jan,

> even though I would go to freeze back the sauce in its original
> apple shape in this world... ;)

I'm not sure it would really be quite the same as a regular apple anymore, especially when you tried to bite into it! :)


> By searching the internet on this topic so far I could only find the
> NURBS -> Polygon direction and not the other way around.

There are actually some pretty complex tools to do it used for reverse engineering, but they're usually very specialized and expensive.

- Michael

Hi Lejan,
You can look at this website here:

http://www.resurf3d.com/

They have a couple standalone applications that do what you are describing.. The mesh to single nurbs one will fit to an "open mesh" (A sheet if you will) not a closed volume. it works off of stl's.

The obj mesh to solid, will work on closed volumes, but is only approxamating what it works on...

The expensive ones michael mentions will do much better jobs, but again, EXPENSIVE.

Also, you can try these demos for a few days... What you will find, is a nurbs surface fit to some organic shape, at any type of tolerance, will be an Extremly heavy surface created... And then, "What do you want to do with it in MoI?" A very heavy, organically shaped NURBS surface may become "unusable" in any type of situation...

You can check those out to see results, but the higher end ones may really be needed to presnt anything that suits what you want.. Maybe the heavy stuff will be good for what your looking for though...
Burr

Minimal Surface - by maximal effort ... ;)

A small guidline for a sailing trip on minmal surfaces in MoI...



A basic outline of half of a boat hull sketched freely in MoI



Exported from MoI via *.skp and imported into SketchUp



Within Sketchup a plug-in called 'Soap Skin & Bubble' was set to 50x50 resolution to generate a first auto-mesh



By default the plug-in then calculates a minimal surface connected to the intitial outline of the boat profile as if this skin was a
soap bubble



To get a bit more space within the final boat the plug-in was run again with an imaginative inner pressure set to a value of '30'

From there the was a bit tricky to get the final mesh of this minimal surface back into MoI and may vary on your own software.
In this example Sketchup exportes in Collada *.dae into Cinema 4D which exported in Wavefront *.obj into Obj23dmWireframe
wich finally converted the mesh back into MoI's *.3dm format.



Back in MoI the mesh was manually 'cleaned' to get a better view and less snap option for the 'Through points' curve tool



Any other vertical contour curve was then manually re-modeled as well as the overall contour curves based on all end points



Finally all new curves were selected and the 'Network' function then re-created the minimal surface. Mirrowed, merged and 'Full steam ahead!',
which for a sailing boat is probably the most difficult part to accomplish... ;)

Who ever knows a more elegant way to get minimal surfaces to work within MoI is very welcome to give me a note on that!

Jan

Hi Michael,

one notice the order in which you shared your knowledge!

First you let me blunt my teeth on my own re-modeled and frozen apple
and then you name those goodies ...

The bill of my dentist would have perfectly covered those tools!

;)

Jan

Hi Jan, well those tools are not really everyday use kind of tools for general surfacing, they're kind of finicky and advanced tools that can get the job done if you don't mind spending a lot of money and also time involved in learning all the ins and outs of operating them.

That's because the "create apples from applesauce" direction is just not a very natural path to work with things...

So they probably are not a practical solution for you unless you are focused on reverse engineering surface models from laser scanned objects as your primary focus for your work.

-Michael