Porcupine Plots

[jehardiman]

Originally Posted by yacht picasso

So why does this image show frequent lines initially..... and less lines (on the some curvature) less frequently further on? what does it mean??

That looks like a joined line; correct?

[yacht picasso]

no... it was one straight line. then i cornered it with a radious; then i curved it again.
it was basically on straight line modelled into that (what seems like) "funky" shape.

[petlily]

The curve looks like two curves being placed together to me, otherwise the porcupine quill should be spaced evenly along a single curve. You may try to increase/decrease the quill's spacing by increasing/decreasing the resolution of the curve since the length of each porcupine quill is proportional to the curvature at that point on the curve. My humble opinion is that use porcupine only to check the fairness of curve and Mean Curvature and Gaussian Curvature renderings for surface's fairness.

[jehardiman]

Originally Posted by yacht picasso

no... it was one straight line. then i cornered it with a radious; then i curved it again.
it was basically on straight line modelled into that (what seems like) "funky" shape.

Welcome to the problem with the way AutoCAD/AutoShip handles lines, arcs, splines, and polylines.

AutoCad, and by extension AutoShip (which uses the same descriptor base), uses descrete arc segments to generate lines of multiple curvature that weren't formed directly from NURBS (non-uniform B-Splines). Depending on what type of original line entity you used before joining determines how it divides the line up into segments. The rate of curvature is then calculated for each segment.

You could de-curve it then recurve it then use the node tangents to get the shape you want.

[Aramas]

Originally Posted by yacht picasso

So why does this image show frequent lines initially..... and less lines (on the some curvature) less frequently further on? what does it mean??

Firstly, you should never use those square control points to edit a line. Click on the button that says 'edit point/control point mode' and use the one where the edit points are round and not on the curve. If you use the ones on the line it will come out unfair every time.

Secondly, the radius function works by putting in two hard corners like on a chine, then a third point to radius it. So putting a radius on one line effectively breaks it into three discontinuous curves.

Also, the default resolution for lines and surfaces is very low so as to not choke crappy old cpus, and it needs to be turned up to at least 100 (I think default is 20). Complex lines might need to be set at up to 200. When a line has several curves in it the segments are used up in the tighter curves and the less curvy bits will look like they're made up of a few short, straight bits. Turn up the resolution (CRes in the properties) and it will smooth out.

You should be working your way through the tutorials in the manual. Thinking you can just jump in and design a boat off the bat is a bit like trying to paint a masterpiece before you know how to draw. If your fifth attempt at a design is a good one then you're ahead of the curve.

Frankly, I find the idea of designing a boat with generic modelling tools like Rhino and Solidworks a bit odd. A specialised tool is always better than a generic one, but you have to put in the time to learn the peculiarities of your tools. It takes hundreds of hours of practice to be even marginally competent, and thousands to be good at it. Unless you're committed to Autoship then you might want to check out Maxsurf as well. They're both highly regarded, and do things quite differently.

[yacht picasso]

Originally Posted by Aramas

Firstly, you should never use those square control points to edit a line. Click on the button that says 'edit point/control point mode' and use the one where the edit points are round and not on the curve. If you use the ones on the line it will come out unfair every time.

Secondly, the radius function works by putting in two hard corners like on a chine, then a third point to radius it. So putting a radius on one line effectively breaks it into three discontinuous curves.

Also, the default resolution for lines and surfaces is very low so as to not choke crappy old cpus, and it needs to be turned up to at least 100 (I think default is 20). Complex lines might need to be set at up to 200. When a line has several curves in it the segments are used up in the tighter curves and the less curvy bits will look like they're made up of a few short, straight bits. Turn up the resolution (CRes in the properties) and it will smooth out.

You should be working your way through the tutorials in the manual. Thinking you can just jump in and design a boat off the bat is a bit like trying to paint a masterpiece before you know how to draw. If your fifth attempt at a design is a good one then you're ahead of the curve.

Firstly i thank you for your helpful response... it was great help

Originally Posted by Aramas

Frankly, I find the idea of designing a boat with generic modelling tools like Rhino and Solidworks a bit odd. A specialised tool is always better than a generic one, but you have to put in the time to learn the peculiarities of your tools. It takes hundreds of hours of practice to be even marginally competent, and thousands to be good at it. Unless you're committed to Autoship then you might want to check out Maxsurf as well. They're both highly regarded, and do things quite differently.

Secondly i thank you for this priceless advise... You are right Aramas... WHAT WAS I THINKING... I wasn't born with the innate ability, as you were, in designing!! So i guess i'll have to learn from scratch as most people like me. When i get to University i'll start taking the courses...but i'll have to wait! In the meantime... I'll try and get as ahead as possible... If you don't mind.
If you wanna help me when you see my questions... Please do, i really value everyones information and i appreciate the time taken to help me.

Plus my sign name says it all.... PICASSO COULDN'T DRAW... YET he created master pieces! ... go figure

ps: i did all the tutorials... but real expertise comes with practice.

[Aramas]

lol - I seem to insult people without meaning to

The point that I was trying to make is that a lot of people think that design is easy and they can just bash out a boat design and save on design fees. Like any other creative activity, design is hard and takes a serious commitment to get anywhere with it. Not only that, but we have to produce a lot of crap before we do anything good. Of course there's always the mythical genius that turns out a masterwork at the age of twelve on their first attempt, but most of us aren't that lucky.

Good luck with it

[yacht picasso]

thank you Aramas... that is very kind.
Although... mine is just a hobby for now, that a really enjoy doing... it's like playing a video game, but much more satisfying!

i hope to receive your help in more of my questions to come!