[Bf-docboard] 3D Concepts and Fundamentals Chapter

[Matt Ebb]

I have a minor critique - since this is a beginners/fundamentals chapter, I
think it would probably be best to keep things simple and concise, and
tackle the left-hand/right-hand co-ordinate system disparities somewhere
else. I worry about overloading the new user with so much information and
idiosyncracies right at the start when they're trying to get their heads
around 3D in general.

Or another thing you could do is describe everything in the diagrams with
Blender's co-ordinate system, then put in a little 'aside' box a paragraph
mentioning that other programs do things differently with Y axis upwards
etc.to keep it a bit less confusing.

Anyway, overall it's great!

Matt

----- Original Message ----- 
From: "Jason Oppel" <pato@myrealbox.com>
To: <bf-docboard@blender.org>
Sent: Thursday, June 05, 2003 12:48 AM
Subject: [Bf-docboard] 3D Concepts and Fundamentals Chapter


> It has been a long time since I promised to tackle the 3D Concepts and
> Fundamentals Chapter so I thought I'd show everyone what I have so far and
> hopefully get some feedback.
>
> I managed to finish the first section and most of the second (one more
> section on rendering remains unwritten).  The second section obviously
> needs some more content but I thought I'd see what everyone has to say
> about what I've written so far. :-)   Comments and criticism are welcome!
>
> Thanks,
> -Jason <Pato>
>
> Introduction
> ============
> 3D applications have never been more accessible or indeed more powerful
> than they are today.  Despite this fact most 3D modeling packages still
> cost thousands of dollars and are still well above means of most hobbyists
> and beginners to purchase.  Blender has eliminated this barrier of entry
so
> that anyone can now use a powerful professional level 3D modeling package
> as Blender is available for free.  We the authors of this book and the
> Blender Foundation are thrilled to present you this Official Blender
Manual
> which will undoubtably help you release the 3D artist lurking within you.
> By the end of reading this book you should have a firm understanding of 3D
> concepts and how to apply them using Blender.  Along the way you're also
> bound to create a some images and 3D scenes you can be proud of!
>
> While Blender's interface is quite different from other 3D applications
> you'll find that as you use Blender more frequently (called "blending" by
> Blender users) that its interface will actually make you extremely
> productive and efficient.  While at times Blender may seem daunting to
> learn (as are all 3d modeling applications) remember that it was designed
> with a professional workflow in mind and there is a pot of gold at the end
> of the rainbow.  The reward from learning Blender is that you'll be able
to
> fly around your 3D creations with astounding speed and produce impressive
> artwork at an astounding pace.
>
> As you're reading through this book try not to forget that despite all the
> magical technology behind it Blender is really just a medium through which
> to create art.  Through the hands of a skilled artist whether they're
> painting a picture, sculpting clay or modeling a complex scene in Blender
> the same artistic skills and talents of composition, proportion, color and
> light are being used and it's only the medium changes.  We encourage any
> aspiring serious 3D artists to learn and practice traditional artforms
such
> as sketching, modeling or painting.  The skills you learn in other art
> forms will make you a far better artist and give you a larger base of
> creative experience from which to use as a launching pad for your 3D
> creations.
>
> We hope that you find 3D modeling a fun (and sometimes an addictive)
> pursuit as we do.  Blender will help you develop the skills necesarry to
> develop your 3D artistry as far as your aspirations will carry you.  Blend
> On!
>
> Getting Oriented
> =================
> You may recall during your geometry and algebra classes at school seeing a
> graph similar to Figure 1 [show graph with x, y and z axis with a point
> mapped out at (1,1,0)].  The graphing system as seen in Figure 1 is called
> a Cartesian Coordinate System.  The Cartesian Coordinate System is the
> standard way that all 3D modeling applications use to define 3 dimensional
> objects (with a few minor variations).  Using this system we can describe
> any point in 3D space.  In this graph the horizontal axis (the x-axis) is
> used to describe the width of objects while the vertical axis (the y-axis)
> describes the height.  Of course we still a way to describe the depth of
> objects and that's the z-axis as seen in Figure 1.  Using the x, y and z-
> axis (commonly refered to as simply x, y and z respectively) we can use
our
> new found knowledge to define any point or shape in 3D space.  As we see
in
> Figure 1 the point mapped out is one unit to the right, one unit up and
> zero units deep.  To extend this concept to shapes we see that the cube in
> Fig. 2 [show cube with x, y and z mapped out on it] is one unit wide (x
> axis) one unit tall (y axis) and one unit deep (z axis).  Similarly you
can
> describe any object whether that object is a car, a plant or even a human
> in 3D space no matter how complex using x, y and z coordinates.
>
> Now that we have a way to plot locations and describe objects in all three
> dimensions let's take a look at how Blender handles 3D space.  Start
> Blender and press NUM1 to change our view so we're looking at our scene
> head on as seen in Fig. 3 [show standard blender startup scene in NUM1
view
> with the axis indicator highlighted in yellow].  If you look at the lower
> left hand corner of the 3D viewport you'll notice that there is x and z
> axis indicator (highlighted yellow in Fig. 3) to keep you oriented.  Now I
> hear you screaming from here that y and not z is supposed to denote
height.
>  Well, this is one of the "slight variations" I spoke of earlier.  Blender
> (and many other 3D applications) uses what's called "left handed 3D
> coordinates."  In left handed coordinates two of the axis (the y and z in
> this case) are flipped with one another. In Blender (and other "left
> handed" 3D applications) the z-axis defines height while the y-axis
defines
> depth.  Let's see if that's right.  Press the NUM7 pad to change our view
> so that we're look overhead on our 3D scene.  Sure enough the y-axis
> defines the depth of our default plane and the x-axis still defines width.
>
> Modeling Approaches
> ====================
> Just as a painter can use different kinds of paint to create a painting
> similarly as a 3D modeler you have lots of different methods you can use
to
> create your 3D masterpiece.  Experience will guide you on when to use
which
> method but we can start you on this road by describing the two most
popular
> ways of creating objects.
>
> Polygonal Modeling
> ===================
> To understand polygonal modeling you first need to know that a polygon is
> any three or four points linked together to form a triangle, square or a
> rectangle (even irregular shaped ones) as shown in Figure 4 [picture of a
> few different looking polygons in edit mode].  Each of these individual
> points (seen as yellow dots in Figure 4) is called a "vertex."  The lines
> linking each vertex together is aptly named an "edge." The art of
polygonal
> modeling at it's heart is stringing polygons together and manipulating
them
> to create more complex objects as seen in Figure 5 [picture of some
> wireframe mesh (perhaps a human body)].  As you see in figure 4 the object
> is comprised of only triangles linked with one another.  It's worth noting
> that whenever you see a model rendered in this fashion it is often refered
> to as a "wireframe mesh" or simply a "mesh" as it looks like it's made of
a
> wire mesh.  Polygonal modeling has a number of advantages as listed below:
>
> 1. Today's video cards efficiently handle polygons
> 2. blah
> 3. blah
>
> blah blah blah.
>
>
> Curve and NURBS Based Modeling
> ===============================
> blah blah blah.
>
> 1. Well suited for creating organic forms such as humans.
> 2. User defineable resolution (the degree to which curves are rendered
> accurately)
> 3. blah
>
> blah blah blah.
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