Explore
For Enterprise
Join for Free
Log In

Artes e Humanas
Negócios
Ciência da Computação
Ciência de Dados
Tecnologia da informação
da saúdesaúde
Matemática e Lógica
Desenvolvimento Pessoal
Ciência e Engenharia Física
Ciências Sociais
Línguas
Notas
Certificados

Explore todo o Coursera

Navegar
Pesquisar
For Enterprise
Entrar
Inscreva-se gratuitamente

3-4 Flower Modeling

Loading...

Computação Gráfica Interativa

Universidade de TóquioUniversidade de Tóquio

4.4 (168 classificações) | 39K alunos inscritos

Computer graphics can be a powerful tool for supporting visual problem solving, and interactivity plays a central role in harnessing the users' creativity. This course will introduce various interactive tools developed in computer graphics research field with their design rationales and algorithms. Examples include enhancements to graphical user interfaces, authoring tools for 2D drawings and 3D animations, and interactive computer-aided design systems. Rich live demonstrations and course assignments will give you insights and skills to design and implement such tools for your own problems.

Visualizar o programa do curso

Habilidades que você aprenderá

3d computer graphics, Algorithms, Robotics, Computer Graphics (CG)

Avaliações

4.4 (168 classificações)

5 stars
118 ratings
4 stars
24 ratings
3 stars
12 ratings
2 stars
5 ratings
1 star
9 ratings

JF

Nov 08, 2015

Estou gostando muito do tema, do professor e do método de avaliação. Nota 10 para esse curso

AI

May 17, 2019

It was useful to understand the basic for my research work

Na lição

3D Geometric Modeling

In this module, we rise up from 2D plane to 3D space, and discuss 3D geometric modeling methods. Topics introduced are; suggestive interface for architectural models, a sketch-based modeling system for freeform shapes, a curve-based shape control method, a flower modeling system, and volumetric texture. You will see how 3D objects can be easily and quickly modeled by specially-designed 2D user interfaces!

3-1 Suggestive Interface9:24

3-2 Sketch-based Modeling14:33

3-3 Shape Control by Curves9:51

3-4 Flower Modeling10:01

3-5 Volumetric Textures11:29

Ministrado por

Takeo Igarashi
Professor

Transcrição

Our next topic is flower modeling.

This is an example of very domain specific modeling operations.

And the work we introduce here is called floral diagrams and inflorescences.

The problem we present here, discuss here is

flower modeling, and flower modeling is very difficult.

It has very complicated geometry.

With you know, petals and sepals, and

also, at the same time, complicated structure.

So, again, each element has complicated shape, and also

we have a very complicated arrangement of interior elements.

So that's the problem we want to address.

And our approach is like this, for handling complicated geometry

we use very specialized tailored sketch interfaces for individual- for all our elements.

For handling complicated structure we

again, provide a very specialized structure editor.

By combing a very specialized system we can make it very

much easier for the user to design various kinds of flowers.

Let me show you a video.

So here's a problem we would try to address.

You know, this kind of flower diagram- flower

models consists of many small elements obligated together.

And then we have complete skeleton structure like this one, and like this one.

[BLANK_AUDIO]

And then what we do is use a traditional representation called

floral diagrams, and inflorescences as an interface

for designing our flowers in a computer.

[BLANK_AUDIO]

So floral diagram, defines arrangements of elements for individual flower.

[BLANK_AUDIO]

Inflorescences defines an arrangement of aggregation of flowers

into this model.

And as you see, user can interactively operates the diagram,

and then you continuously see the updated geometry

[BLANK_AUDIO]

And the modeling process start with the defining of a floral diagram.

So in the flower base you arrange individual elements,

and then you can see a 3-D measure preview here.

[BLANK_AUDIO]

So as you see, this is a

very specialized dedicated modeling system for flower arrangements.

[BLANK_AUDIO]

After our getting a diagram, now, the user defines a geometry.

As you see, we provide a very, very simple sketching interface for defining a shape.

But here, system automatically generates a surface of revolution

And for each floral element, our

system provides a very dedicated sketching interface.

So this one is generating I think is a- sepals

[BLANK_AUDIO]

And then this is a petal modeling, so you draw three lines.

And then you get- instantly get a 3-D model.

And from the side view a user draws a line, and you get a deformed shape.

So with just only four strokes, you will get a very huge form of flower element.

And you can continuously add more and more strokes, to get more detailed shape.

And then after having floral

diagram and 3D components, you establish correspondences,

associations, and then with that information

our system start to generate an aggregated composition.

And then you will get a beautiful shape this way

And now we assemble them together into a, structure using inflorescences.

So you get this template, and then you change the shape, and then you will get the shape.

And now we define axis, center axis by sketching.

This is an interesting part, so you draw two dimensional stroke to

define axis, and then system generates 3-Dimentional axis let me see.

So user draw a stroke, and then as

user draw, system would automatically generate a 3- dimensional axis.

As soon as you finish drawing you can rotate

and you will get the reasonable 3D shape.

[BLANK_AUDIO]

Yeah, so here's a little bit more

description about 2D input to 3D stalk part.

So without depth assignment if you project your input into

a flat surface it looks like very unnatural, a very flat shape.

However, with our algorithm.

User draws a stroke, two-dimensional stroke, and

the system automatically assigns a natural, naturally

looking depth variation, so if you look

from, look from a sideway, it looks natural.

So to do this, what we do is to assume

that three-dimensional curvature is always constant in 3-D space.

With this assumption we can efficiently compute the depths.

And then here’s a couple of results.

I think it is very tedious and time-consuming to generate

these kinds of models using traditional 3D general purpose 3D-modeling systems.

But with our system, it's very, much, much faster.

Of course, it takes certain time, but it's much faster than using traditional methods.

And you can easily modify them.

[BLANK_AUDIO]

Yup, that's it.

And then, here’s a couple of results.

So these are 3-Dimentional shapes and these are the structure editors.

And then here let me briefly describe the algorithm of 2D stroke to 3D shape.

And how to infer depths. Here’s a little bit of details. So as I said the basic assumption.

The main idea is to assume constant curvature in 3-D space.

Which means second derivatives, x-position and second derivative of

zed- z positions by y value, is constant.

Y is a growth direction.

See here again, this is two-dimensional input on X-Y plane.

Y is growth direction, and x is sideways vectors and

then we compute, we try to compute z values in this way.

So in order to do it, first we project strokes onto x-y plane and resample.

So we put the sample points here, and

then we suppose that 3D curvature is constant so.

Second derivative of X along Y and second derivative Z along Y equal constant.

And we know this value by this shape.

And we also assume this constant value

by maximum of this value, probably somewhere like here.

Maximum curvature.

And here.

The curvature in X-Y plane gets smaller here.

But instead we at, assign large value here,

which means large curvature in Z directions, like here.

So this is given value, and this is given value, and you get this value.

And after get these values second derivative of Z, then we just integrate twice,

and then you will get the values, so that is the algorithm.

So to learn more, the original paper can be

found in SIGGRAPH 2005 titled Floral Diagrams and Inflorescences.

Interactive flower modeling using botanical structural constraints.

And plant modeling has a long history of

research, and one famous book is called The

Algorithmic Beauty of Plants, and this one discusses

lots of interesting techniques to get 3D models by rule-based systems.

So here is a, one example, you draw this kind of synthesis rule, and you

will get this kind of very complicated

structure, and this is very beautiful mathematical system.

However, it is a little bit unintuitive for our artists to design model.

So recent-recently people use this kind of

graphical rule editor to generate a 3D shape like this.

And this, and this paper about the

paper titled, Modeling Methods and User Interface for Creating Plants, was

currently available as a 3D-modeling system called XFrog.

And this is a very popular tool.

So if you are interested in plant modeling I recommend you take a look at these systems. Thank you.

Explore nosso catálogo

Registre-se gratuitamente e obtenha recomendações, atualizações e ofertas personalizadas.

O Coursera proporciona acesso universal à melhor educação do mundo fazendo parcerias com as melhores universidades e organizações para oferecer cursos on-line.

© 2019 Coursera Inc. Todos os direitos reservados.

Baixar na App Store

Baixar no Google Play

Coursera
Sobre
Liderança
Carreiras
Lista de cursos
Certificados
Certificados MasterTrack™
Notas
For Enterprise
For Government

Comunidade
Learners
Partners
Developers
Beta Testers
Translators

Conectar
Blog
Facebook
LinkedIn
Twitter
Instagram
YouTube
Tech Blog

Mais
Termos
Privacidade
Ajuda
Acessibilidade
Imprensa
Contato
Diretório
Afiliados