Monday, March 7, 2011

Making a Dinosaur in Carrara (Spline Technique)

So after having requests from a few people asking how I make my 3D Dinosaurs, I've finally made the time to do a quick series of tutorials. To be honest overall these will probably be of only direct use to Carrara users, but for you general readers this will give you a bit of insight into how I roughly make my 3D graphics (I don't use a traditional format afterall).

I am using, again, Carrara. At moment I'm on the latest version, number 8 (which they have finally fixed the majority of bugs on... after a mere 9 months!), but my tips for today are good for any version of the program (and even its ancestor software Raydream).

Where I am a real rebel is I will be showing you how to make a Dinosaur today with a Spline editor. Most 3D people make organic creatures with Vertex or Metaball methods. So if you're looking for insight into those realms I am not the guy for you.


So what is a spline object?

A spline is an "object" created by drawing several cross sections along a linear path, and filling in the spaces between the cross sections with "mass". While this might sound complicated it is actually rather simple.

Using this simple cylinder above as an illustration, the cylinder is formed by a single circle cross section which the computer stretches along the line to create the remaining mass. If you were to insert additional cross sections and change them from simple circles you can make your arm (as an arm is basically a slightly distorted cylinder).

If this still doesn't make sense, hopefully it'll make more sense as I jump into how I make my Dinosaurs.

So Carrara people, you're going to have to create spline objects to follow my technique. The necessary icon is show above when starting in the overall modelling window of a new project.

TIP: Try to drag the spline tool towards the middle of the modelling grid so you're object isn't huge or way off the modelling plane.

Once you create a spline object you should pop into here, the spline editor. Welcome to my workshop of wonders...

If you want to model in here you'll have to learn and master the use of the extrusion path (those purple lines you hopefully can see on the grids above... sorry the picture was shrunk in the upload).

Taking a closer look at one of the extrusion paths (there are two out of the three possible planes. Here I'm looking at the Y path... you will also in the long run want to get to know the Z plane path as well), the key thing are the extrusion points. Those are the black dots you can see on the purple line.

Whenever you create a new Spline object you will start with a basic extrusion path. This has a cross section point (red arrow) and a extrusion point (blue arrow). You are not restricted too, nor will you typically use, just one of each. You can have as many of either as you want. Though the more points you add the more difficult it will be to manage certain attributes on your object (but too few will make your life difficult with the other attributes... there is always a cost to these things).


What is the difference between a cross section point and an extrusion point?

The main difference is that a cross section point will more define your objects make up and look, while an extrusion point is a means of subtly influencing and tweaking the object. Both are necessary, but cross section points in the end are the most important.

So let's start with cross section points, as 1. their the most important and 2. you can't start really creating an object without cross sections.

Again a new Spline object starts with a single cross section point at the back of the extrusion path.

Tip: Sadly there is no display difference between a cross section point and an extrusion point. They both are displayed as black dots. You'll just have to try and remember which are which. If you loss track (don't worry we all do) swap to the director's camera point of view which will let you easily and quickly see which are which.

Selecting one of the shape primitive options from the top icon bar, draw an initial shape on the cross section.

If you stick with the initial format of a new spline, you're object will be determined from its back end. While in some cases this might be handy for some types of models, in my experience it is not so good for organic parts.

We're going to want to customize your initial setup.

Grabbing the add point tool, shown above, you can click on either extrusion path (side or bottom) to add a point. Remember to press the ALT key if you want a cross section point. Just left clicking with the add point will give you a standard extrusion point, NOT a cross section!
For my technique you'll want to add a cross section roughly in the middle of the extrusion path. Than as close to the original cross sections end of the extrusion path you'll want to add a extrusion point.
That should give you an object like this. Note how I now have 2 cross sections (both circles, but this will not be the case for long) out of 4 points. Those other two points, while not defining my objects overall shape, will be important to close the object with a solid end point.

Next I personally like to get rid of the cross section at the end of the path. The reason being that cross section have a greater effect on the objects shape, and in the ends I like to have a more easy and subtle means of controlling my object.
So select the remove point tool from the top and click on the end cross section to remove it from the path.

This now leaves us with a perfect starting point for ANY body part of a Dinosaur you might want.
We have three points (for now). A single cross section in the middle (marked by the red arrow) and two extrusion paths (blue arrows).
Again so you understand what is happening the cross section (red) is defining the extrusion points (blue), and at moment as I haven't modified any attributes of the extrusion path or added any more cross sections I'm getting a perfect cylinder.
Let's start changing this into something more Dinosaur like.

First we're going to want to change our cross sections. I personal like to start with a single customized cross section (as opposed to a generic circle of square), and work off this on all new cross sections.
Tip: Remember that if you add a new cross section when there is another predefined cross section on the path, that your new cross section will be a copy of that original cross section's shape. You can use this to your advantage with some quick advance planning.

To customize a cross section shape I personally start off with a primitive shape (typically a circle). I will than ungroup the shape to allow me access to its controlling points. To do this select the shape by clicking on it, than either by going into EDIT and choosing Ungroup or simply hitting Control U.

You will suddenly have a number of points around your object and their vector handles. You can move the points and vector handles any way you'd like around the cross section plane. So any possible shape you can imagine is possible... With enough time and play.
The shape points represent connecting points of the perimeter of the shape. The vector handles control the curvature (or lack there of) of the lines that connect the points.

So to easier see how we're changing a cross section we'll want to switch viewpoints. Selecting our view point option pick either Front or Current Selection to get a clear view of a cross section.
TIP: Try to do key cross sections first, as the more you add the harder it is to see them from the front, as Carrara stacks them all in this view. Meaning that it will get more difficult to tell layers apart especially when you're making a very linear object like a Dinosaur's body part.

Okay so here is your cross section up close and personal. Again this is the best when to manipulate a cross section. At least at the start of modelling.

To more easily customize our circle we're going to want to add points. For this select the add point tool again, and add some points to your circle where ever you are going to want to pull, distort, or reshape the cross section's shape.

Pulling the points around the cross section plane, and modifying the curve with the vector points you can start to make Dinosaurian looking cross sections.
You will have to play a little bit with this part to get the hang of it. I could do a tutorial section on it, but in my experience the only way to really understand this is to do it yourself. So enjoy, and if you hit any real snags let me know in the comment section and I'll try to help you out.
TIP: When finished reworking a particular cross section go into Section and select Centre. This will centre your cross section shape on the cross section plane, and make it easier to find and line up other cross sections with. You can also regroup a Cross Section by hitting Control-G to easily drag the shape around the cross section plane (as opposed to have to select EVERY point while an object is ungrouped).
So once we have modified our cross sections the way we want, how do we modify the overall extrusion path?
To do this we need to pick an extrusion envelope which gives us a means of controlling the way cross sections and/or extrusion points connect to one another.
Click on Geometry and select Extrusion Envelope. You have several options. Most of the time you'll want the Free mode, but to initially start off with say a symmetrically body part like the top profile of a head you can pick symmetry in plane.

In any envelope your points will suddenly appear above and below your extrusion path alone both extrusion axis. The points will all be connected by blue lines. This is simply a visual means of seeing how your objects points are connecting to each other.

You can grab any of these points and move them along the extrusion plane. Depending on the type of point and the envelope you have selected different things will happen.

Moving a Cross Sections point here will cause every non Cross Section point connected to it up until the next Cross Section to move with it in proportion to how much you move that one Cross Section. If you are in a symmetrical envelope the other point(s) of that particular section will move accordingly.

Again testing out and playing with this part of splines will clear up any questions you have.

Lastly you can curve and smooth out the connections between points. To do this you'll need to select the vector tool as shown above.


With this you can give any point along the extrusion path vector handles that will allow you to curve the connection lines and thus curve your object.

Applying multiple cross sections along the path, modifying their shapes individually, and finally editing their connections along the extrusion path is exactly how I create and modify my Dinosaur parts.

This just requires multiple rounds of all the steps I just outlined for you in this lesson. If you found this useful or interesting let me know in the comment section below, and I will do more if people want more.

Till then happy 3Ding, and good luck with your own three dimensional prehistoric creatures!

3 comments:

davidmaas said...

ouch. Nurbs-modelling organic forms.
Once I get my system running again, If you think it'd be of interest here, I'll try to complement your tut with a polygonal method, detail up method. (I presume from the first post that Stu is going to demo the volume-down or box-modelling method).

Stu Pond said...

Great tutorial - I haven't used Carrara for years although I really liked the interface. I will be doing the box-modelling method (or sort of) but these tools vary so much between packages. I never thought of modelling with nurbs this way though. Good stuff.

Traumador said...

David- Nurbs?... I assume that is another name for Splines?

All I have to say is don't knock em till you try them. Mind you I'm at the point where I'm starting to look into vertex modelling to add details and smooth out a few things or add more realistic wrinkles.

At least for the time being I will be creating the base of all my critters this way and just switching to vertexs once I'm at the detail stage. My texturing methods and techniques are too reliant on the animal being in multiple pieces.

Totally feel free to fire up a post on your own method. I'd be quite interested.

Stu- Glad you liked it. I can understand leaving Carrara. If I had the time to learn a new program I might very well jump ship too. Especially after the nightmare that was Carrara version 8 ugh. The bloody thing crashed 2/3 renders... NOT even remotely acceptable for a 3D program!

However due to lack of time for learning a new program (and trying to teach myself Adobe Flash right now too), and having been with Carrara since the early Raydream days I've toughed it out. I'm hoping this loyality to a moderate program doesn't hold me back from doing some pro level palaeo-art someday.

Excited to see where you're box-modelling method goes.