Review

From CAD User Mechanical Magazine  Vol 18 No 02 - FEBRUARY/MARCH 2005

Serious amateurs and CAD professionals can learn a lot about 3D character modelling and animation from Eovia’s Carrara 4 complete 3D Solution.

From the sublime to the ridiculous! Having thoroughly enjoyed romping through the text free delights of Cosmic Blobs, the 3D modelling and animation package for kids, which we reviewed in the last issue of CAD User – I now find myself at the other end of the scale, reviewing a 3D modelling and animation product that comes with a hefty 600 page manual – and enjoying it just as much!

Eovia’s Carrara 4 has its own selection of Blobs, part of its Metaball free form modelling tools, that invites users to insert and play around with blob primitives in much the same way that Cosmic Blobs does. And, apart from one or two other minor functions, that’s about as far as the similarities go. Cosmic Blobs makes it easy for kids. All of the mechanics and tools are hidden behind its macros – even the skeletons inside the primitives, and the limited number of preset animations that they allow kids to use. Carrara 4 hides nothing! It is a professional package that allows users to create 3D models - constrained only by their imagination - to render them using a wide variety of patterns and textures, to insert complex skeletal structures and then to animate them using forces, constraints and mechanical formulae to simulate real life action.

Developed originally for the Mac market, the screen is a refreshing change from the standard Windows displays, and contains a wealth of information, supported by a comprehensive Help index which is, basically, the aforementioned manual in PDF format (actually, a bit more, as the PDF document runs to 800 plus pages!). I am not a fan of software manuals. I like to think that most software, adhering to basic principles, should allow a user with a modicum of knowledge to bludgeon his, or her, way through the software, intuitively, allowing them to backtrack on errors, and to explore the vagaries of the software unhindered. Although Carrara 4 is very good in this regard, the very nature of the tasks that are being attempted, and the dissimilarity of some of the functions to standard 3D modelling, force one to seek help from the Help function, or from the manual itself. Which is where I have to eat my words, as they are both very good indeed – clear, precise and well laid out – and contain easy to follow examples of each function.

Scene 1
We are not talking 3D modelling here. We are creating scenes for 3D illustrations, animations, and web output. Hence the appearance of terminology that will be unfamiliar to most CAD users. Carrara documents are called scenes – a collection of objects, light sources and cameras, saved together in a file. Each scene has different windows – called rooms – where users can create the various elements that they want to use.

The Model room is used to create objects, giving the user access to spline, vertex, metaball and text modellers. The spline modeller is similar to Free Form modeller in Studio, and the vertex modeller equates to Studio’s Mesh Form modeller.

Objects are brought together in the Assemble room (naturally), where users can add lighting and cameras, and add other effects to the scene. Positioning objects in this –and in other rooms – is aided immensely by the x.y.x grids, the simplest method I have used of placing objects in conjunction with each other in 3D space.

Animations consist of series of single frames, each differing slightly from the preceding frame, and which, run in sequence, produce the animated effect. Carrara’s Storyboard room displays multiple frames of the scene, allowing users to create and view changes over time. Although users can switch from room to room effortlessly, most of the Assemble room tools are available in the Storyboard room.

Two other rooms allow users to create, edit and apply shaders to an object – the Texture Room, and to specify render settings for images or animations –the Render Room.

How does it work? Very simple. A simple scene is created in the Assemble room by dropping in object primitives. These can then be turned into finished objects by accessing the appropriate modeller – a double-click away – and, if the scene is to be used for animation, you can switch to the Storyboard room, creating the animation at the same time as you create the scene. Shaders are then added in the Texture room, and the scene switched back to the Assemble room to add modifiers and lights, or to add and position cameras, then out to the render room for the final rendering.

To add further realism, individual objects can be animated, using the Sequencer, or apply modifiers or physical properties to objects that allow them to exhibit natural actions when animated. Two of the examples provided with the software show these effects very well – a frog like creature that can jump, showing the skeletal structure that has been applied, the constraints on the movement of the legs, and the sequence of steps in the animation. The second shows an animated sequence where mechanical forces have been applied – a weight dropping onto a see-saw, which projects another object into the air.

Modelling Objects
Each of the modellers available – vertex, spline and metaball – works in a different way to each other, and has, consequently, a unique window with its own tools and menu commands. Whilst they are being used, the entire scene is on view in a separate Scene preview window, so that any work done on the model can be kept in context. To the right of the display are a series of icons that allow the user to switch instantly from a single window to multiple windows – top, front side and isometric.

Vertex modelling is a very flexible tool that allows users to sculpt objects from primitive objects, such as cubes, spheres, cylinders etc., by editing edges, vertices and polygons on the object, applying spline modelling tools to perform extrudes, lofts and sweeps. More complex models can be created by increasing the number of edges, vertices and polygons in the model. Users can even start with 2D objects and open and closed polylines, extruding or seeping them to create 3D objects. Polylines can also be used to create complex 3D extrusion and sweep paths, including bends and spirals. Lathing and lofting, two other useful tools, allow define 3D lathe profiles with circular cross-sections, or to stretch a surface (lofting or skinning) over several cross-sections to create a complex object – performing a straight extrusion form one cross section to the next. More advanced lofting requires the spline modeller.

Spline modelling allows users to extrude 2D shapes into 3D objects which can then be refined using an extrusion envelope. Extrusion can either be straight, scaled – increasing or decreasing the size of the extrusion as it unfolds, or lathed (think of symmetrical objects that could have been produced on a lathe). Any extrusion besides the straight extrusion is carried out within an extrusion envelope. Skinning with the spline modeller allows users to choose shape to shape, or point to point skinning, making the surface sharp-edged or smooth.

Spline modelling is displayed in the spline modelling window, providing the grids (working boxes) that can be used to draw sweep paths, cross-sections and extrusion envelopes. Icons underneath the single/multiple window toggler allow different grid planers in the working box to come into focus –essential for use as a drawing plane, or for creating extrusion or sweep paths in 3D. The lines created are shown as ‘shadows’ on the grid in all orientations – creating horizontal and vertical projections of each line. Cross-section planes allow users to create 2D cross-sections, which are, in effect, the skeleton of the object, and are shown as separate grid planes in the working box.

The extrusion envelope, located in the geometry menu, allows users to control the curvature of a 3D object around its sweep path, by scaling the objects cross-sections. It consists of four Bezier curves, two on each sweep path plane, which guide the sweep along the path, which can be edited to scale the cross-sections.

All modellers come with various windows to set preferences –working box sizes and grid spacings for grid settings, edge propagation angles and rotation constraint angles – even maximum numbers of selections to be saved to modify the behaviour of the vertex modeller. Spline modelling preferences allow users to set options for resizing shapes and groups, snapping to grid lines, toggling the grid display and setting up display box colour schemes, etc.

Metaball modelling is the one I liked using most, as it allows organic shapes to be created by blending primitives called blob elements. Blobs are not solid 3D primitives. They are 3D influence fields, and can be set up to have positive or negative attraction, so that when approached by another blob primitive, they can attract each other and blend together, or repel one another, causing negative distortions in the shape of the blob. In this way, you can graft on appendages to amorphous blobs, elongating them to become legs, heads and so on.

Ghost Menus
Each modelling window uses ‘ghost’ or cursor menus to simplify and speed up the
modelling process. Right clicking on the model causes these to appear – enabling common modelling commands, such as scale, move, rotate, zoom and so on to be instantly available – ghost because they are only available whilst you hold down the mouse button. A bit disconcerting at first, but very practical.

Grouping and Linking
Grouping objects within a scene is basically the same as grouping in other software, holding the objects together in stasis to simplify structuring and navigation around the scene. Linking is somewhat different. It enables separate objects to be tied together, by defining a parent-child relationship between them, so that moving the senior part –the parent – affects the junior part. (There is an exception to this rule in Inverse Kinematics).

Linking is used to create articulated structures, such as an arm, with a hand linked to the forearm, the upper arm, and the shoulder. The child’s objects movements in the linked objects hierarchy can be constrained at each level to mimic the natural constraints on arm movement – i.e. you can’t bend the forearm behind the upper arm!
Constraints also allow users to simulate ball joints, lock child objects to parent objects and simulate shaft and sliding operations.

Character Animation
Bones and skeletons. A bone’s articulation, or joint, is shown as an octahedron around its centre of rotation. You can see it in the wireframe of an object, but not the rendered model. The hierarchy of bones in an object is, obviously, the skeleton. Skeletons are created in a scene by dragging in the Hierarchy section of the Sequencer to create associations.

Once a skeleton has been defined, it can be animated by creating an Inverse Kinematics Chain. This defines the relationship of each part of the skeleton, and how they work with each other, and is the basis for all animated motion. This is where some fancy software comes in. If the object that contains the skeleton has been skinned to create a smooth surface, changing the shape of the object (by bending an arm) will modify the skinning. The influence that the object can have on the skinning process can be edited using the Bones Influences Properties box.

Conclusion
Haven’t been able to do more than scratch the surface of Carrara 4 with this review, although I hope that it has provided an insight into how it works, and how comprehensive such a programme is –and needs to be. Having said that, the software doesn’t cost megabucks. It is priced in the lowish hundreds of pounds, and is aimed at
serious amateurs and professional CAD users who want to get to grips with 3D character modelling and animation. I enjoyed using it, and will continue to play around with it for entertainment, even though I have no desire to compete with Pixar Studios at the moment.

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