Resetting Scale

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 From:  Mark Brown (MABROWN)
2610.1 
Hi everyone,

I am currently using MoI to design a model of a ship which I intend to create in physical form using paper card. Things are going quite well. I've managed to work out how to unfold my MoI model to flat shapes via Google Sketchup using a free Ruby script and also how to create a pdf file with correctly scaled parts by using a freeware pdf driver.

The ship's hull in the attached image was 171m long in reality but is 219m long in MoI. I need some help to resize my MoI model to match its real world dimensions, or better, to make MoI recognise that my ship is 171m long by resetting its internal scale to match my model. The reason this is a problem is that I have several plan images which do not rescale with the rescale of my model. The images took me ages to arrange and I don't want to upset their relationship to my partially completed model.

Any ideas would be much appreciated.
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 From:  Paolo (PAOLOLOBBIA)
2610.2 In reply to 2610.1 
Hi Mark,

Draw a straight line from the origin 171 m long on
the x-axis(or y-axis),then draw a second one 219m long(the lines
will overlap).

Select the whole model and run the scale command.

Select endpoint on the origin as origin point,then select the
endpoint of the 219m long line as first reference point.

Move the cursor to the endpoint of the 171m line to select
the second reference point and release the mouse button.
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 From:  Michael Gibson
2610.3 In reply to 2610.1 
Hi Mark,

> or better, to make MoI recognise that my ship is 171m long
> by resetting its internal scale to match my model.

There isn't really anything like an internal scale in MoI, when you enter in numbers like x=50, y=150 - those are not modified by MoI, they get stored as the numbers 50 and 150 exactly as you entered...

I think your best bet is to scale your model by the method that Paolo wrote above, by drawing in 2 reference lines of those lengths and snapping on to them with the Scale command.

Then for your background images, there is a new "Align" function for background images in the v2 beta (download from here: http://moi3d.com/beta.htm) which allows you to transform a background image in a similar way, by picking 2 original points and then 2 target points, and then the image is scaled (and rotated if there is an angular difference) to map from the first 2 to the last 2. That works like this:



In your case here though you want to have each reference line pointing in the same direction and with a shared endpoint so that there will not be any rotation or lateral movement, only scaling.

Then go through your background images one by one, highlight one and hit "Align", pick the 2 source points, and the 2 target points, and when you finish that your images should be scaled to their proper new locations.

Also you probably want the 2 reference lines to be anchored with a common endpoint at the 0,0,0 origin point, so that everything scales in relation to that point.

Does that handle the rescaling that you need to do?

Also one other note - probably you should save off a backup copy of your model before doing this just in case, right now that Image align tool does not have an undo in it just so you know (it is on my list to tune this up though).

- Michael
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 From:  Frenchy Pilou (PILOU)
2610.4 

EDITED: 30 Apr 2009 by PILOU

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 From:  Jesse
2610.5 In reply to 2610.3 
Hi Michael,

I've been away from the forum for a while...I'm excited to see a new Beta is ready!
The Browser is a great addition.

This new align function for bitmaps makes me curious to know if you're getting closer
to adding "├Ârient from 2 points" to the transform toolset?

Regards,

Jesse
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 From:  Michael Gibson
2610.6 In reply to 2610.5 
Hi Jesse,

> This new align function for bitmaps makes me curious to
> know if you're getting closer to adding "├Ârient from 2 points"
> to the transform toolset?

It kind of doesn't look likely that this is going to happen for v2, the work on the browser has taken quite a lot of time...

One thing that may interest you that is kind of similar though is some new stuff for the edit frame that can help for orienting objects - when you click on the rotate grip to enter in "wheel mode", you can relocate the rotation origin, and instead of only being able to grab on to the wheel like it was set up previously, you can grab a point of an object as the start point for the rotation.

So that allows for things like this now:



The nice part about that method is you don't need to fire up a command to do it, it is available on the edit frame which shows up around your current selection.

- Michael
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 From:  Mark Brown (MABROWN)
2610.7 In reply to 2610.4 
Thanks so much everyone for the responses. This is exactly the detail I needed. This align feature and the new scene browser (even without groups) is going to be enough to have me upgrading (though I hope you keep adding goodies Michael!).

Actually, I really can't do without the scene browser now that I've got it. I like the implementation too as it reminds me of the Primitive Itch Scene Tool plugin for trueSpace which in that software was at the top of my essentials list.

Pilou, the French defense archive is a fantastic resource. The plans section is terrific. One highly accomplished card model designer/builder from the Papermodelers forum has built an amazing model of "Lavoisier", designed in Rhino using plans from the archive.

http://www.papermodelers.com/forum/ships-watercraft/1067-lavoisier-1-250-a-19.html

---
Mark
http://www.homepages.ihug.com.au/~mabrown/index.html

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 From:  Michael Gibson
2610.8 In reply to 2610.7 
Hi Mark I'm glad that the new scene browser in v2 is working well for you!

One thing I wanted to mention - there is a collection of all the release notes on new stuff that is in v2 so far here:
http://kyticka.webzdarma.cz/3d/moi/doc/V2releasenotes.html

- Michael
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 From:  Mark Brown (MABROWN)
2610.9 In reply to 2610.8 
Just a quick note to say thanks Paolo and Michael for the help. My model and images are now scaled just fine at 1:100 and set to millimeters.

---
Mark
http://www.homepages.ihug.com.au/~mabrown/index.html

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 From:  Paolo (PAOLOLOBBIA)
2610.10 In reply to 2610.9 
Hi Mark,

My compliments for your website,
you are a true artist.
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 From:  Frenchy Pilou (PILOU)
2610.11 
Cool images on the site indeed!
---
Pilou
Is beautiful that please without concept!
My Gallery
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 From:  Paolo (PAOLOLOBBIA)
2610.12 In reply to 2610.9 
Hi Mark,

I found another method to scale (silly me answering to fast)

Pick first reference point and type 171/219 as scale factor.
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 From:  Mark Brown (MABROWN)
2610.13 In reply to 2610.12 
Thanks guys for your kind words about my website :)

Thanks also Paolo for the alternative scaling method. I wouldn't have thought of that.

And thanks Michael for adding Sketchup export to MoI. Without the Sketchup export I wouldn't be able to unfold the 3D for paper modeling, so add that as another reason the V2 upgrade will be essential for me.

About the only other thing I would like to see in MoI is the plugin interface. How do you envision that working Michael?

---
Mark
http://www.homepages.ihug.com.au/~mabrown/index.html

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 From:  Michael Gibson
2610.14 In reply to 2610.13 
Hi Mark,

> About the only other thing I would like to see in MoI is the
> plugin interface. How do you envision that working Michael?

Well, there will probably be a few different layers - you'll able to write things that automate existing tools with a combination of HTML for the UI and Javascript for the logic. In fact several people have already done that to make some custom command plug-ins already, check them out here: http://kyticka.webzdarma.cz/3d/moi/

Then there needs to be another kind of component that can be created using C++ code for some more "back end" type heavy calculation stuff. At the moment the interfacing mechanism for this part is not exposed.

Unfortunately documenting and also supporting this stuff is a lot of work, so it may still take a while before that area really gets going. The current priority is still much more on making basic tools that work for "regular" end-users rather than developers.

- Michael
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 From:  Mark Brown (MABROWN)
2610.15 In reply to 2610.14 
Many thanks for the reply Michael.

I'm not a great programmer and not a java programmer at all but I'm always full of ideas!

I've been considering what the future options for unfolding of surfaces within MoI might be. I would be happy with something that works much like the Ruby script does in Skoogle where you click on a face then on an adjacent face and the second face is basically rotated to be in the same plane as the first. This of course works on polygonal objects only. What I would like from Skoogle's ruby script is a bit more automation. I'd also like it to allow overlaps as sometimes I want them.

MoI has first rate polygon mesh generation (I've been relying on it heavily throughout this paper model project) but it generates these polygon meshes only as output to some other format, like .skp. Would it be possible to generate these meshes as editable geometry (straight line "curves" and flat surfaces, basically nurbs "polygons") for re-use within MoI (similar to what your obj wireframe import script allows)? If so then I'm thinking that MoI's current tools such as "rotate" could be scripted to do much the same as Skoogles ruby script.

Chances are, none of that made any sense....

I've had a look at some of the Java from the site you pointed me to (already using some of those and they are excellent). I think I could manage some simple scripts.

---
Mark
http://www.homepages.ihug.com.au/~mabrown/index.html

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 From:  Michael Gibson
2610.16 In reply to 2610.15 
Hi Mark,

> Would it be possible to generate these meshes as editable geometry
> (straight line "curves" and flat surfaces, basically nurbs "polygons")
> for re-use within MoI (similar to what your obj wireframe import script
> allows)?

Usually it is not so good to make NURBS objects out of a tremendous number of tiny facets.

NURBS have a very general purpose trimming mechanism, with the concept of an "underlying surface", which also includes 2 chunks of stuff for every trim curve, a UV curve that lives in the parameter space of the surface, and then also a 3D curve. All this structural stuff tends to be why NURBS are good at booleans - when you boolean 2 NURBS solids, the underlying surfaces of each get to stay exactly the same and only new trim curves have to be calculated. This tends to avoid fragmentation into a bazillion little slivery pieces which is what happens with polygon-mesh booleans - that is one reason why polygon mesh booleans just do not tend to work very well...

However, this kind of advanced and generalized structure for trimming is also heavier than the edge structure of a polygon mesh object.

NURBS can be nice and lightweight in data size when you are using them as they were originally intended - which means for example having a sphere represented as one sphere surface.

But if you instead try to make a sphere made up of thousands of tiny facets, that is not really how NURBS are designed to be used, and in that case the NURBS structure becomes quite memory consuming, since you now have quite a large number of trim curves.

So to make a long story short - although it is technically possible to make a conversion like you are talking about, it can result in a structure that is not really suited well for NURBS and can consume too much memory.

That means it would need to be a kind of special purpose thing, not really a general tool to use in normal circumstances.... That's why I did not make it as a built-in type thing, not yet anyway.

- Michael
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 From:  Michael Gibson
2610.17 In reply to 2610.15 
Hi Mark, also I should probably mention that most likely the real solution to what you are talking about, like being able to rotate or manipulate polygon data in MoI, will be to have MoI support polygon data as a separate kind of object in addition to NURBS data.

But I haven't tried to do that yet though, since it kind of opens up potential for a lot of confusion for how those different kinds of data should interact with one another.

It has helped to keep MoI's interface nice and streamlined by having it focused on dealing only with NURBS data and not polygons yet.

Right now I kind of expect that if you need to work on polygon data that you would use a different program than MoI to do it, like for example Silo or Modo.

- Michael
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 From:  Jesse
2610.18 In reply to 2610.6 
Thanks Michael,

MoI keeps on getting better and better!

Jesse
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