Crane Geo TurnTable

Finished turntable of the Crane Geometry, apologies for the quality - must adjust my export settings and speed it up a little. Note to self - current TurnTable set at 800 frames, probably best off nearer 500-600 mark.

I've modeled the tail stretched out, its rest position will squashed together but i'll create a set driven key within the rig that will allow the animator to spread & bunch the tail.

Identifying Problem Areas

Whilst modeling for animation, it's vital to identify key areas that are going to take most of the stick (by which I mean which areas will require the most deformation) when animated, and ensure that there's enough geometry to support it. Failure to do so will cause headaches when it comes to weight painting the verts.

Wings

Wings are very important! I think i've covered the surface areas of the wings by virtue of the very nature of their creation, so that should suffice. Where the wings and body meet is a different story however. The picture left identifies areas that are worrying me at the moment - there's too much of a gap between verts for this area. Fortunately shouldn't be too much of a biggie to rectify. I could just stick an edgeloop in and wire it into where four edges meet, to bring five edges together.

But I don't want to do this. As I discovered with the Toxic Boy geometry, this just creates massive issues when it comes to weight painting it, its best to have four verts coming together are better than five.  So what i'll do is move these verts down and add an extra edgeloop above that will go around the wing. More Geometry where it matters, four sided geo gives better more predictable deformation.

Better Wings

I've gone into that area, added the geometry and given the whole thing a lick with the relax brush. It's beggining to look like something thats going to behave when animated. What is paramount when modeling geometry intended for animation is to make sure the interior angles where verst meet are as broad as possible. I shall further elaborate below.

Further Elaboration

Imagine this were a perfect square and all its edges were perpendicular to each other, that would make each angle 90° to each other. This will equate to a nice even deformation, by which I mean each angle will reduce or expand proportionately and not crease unless moved through extremity.

Trapezoid

Now imagine this is an isolated section in a piece of geometry in a model. In order to follow the contours, the geometry has to be pushed around, angles have to compromised. In this instance two of the angles are 80° and two are 100°. This is ok but not as sturdy as foolhardy as a nice and solid 90° square.

Triangle

Ever since I first switched Maya on the computer, I have always been told "make sure your geometry is is at least four sided" and this quickly became my mantra. But I never fully understood why, but abided by it. A triangle consists of 180°, so the biggest interior angle a triangle point can have is 60° (if it were equalateral). In this instance (imagine it being the corner of an eye) it goes down to a meagre 20°. Not much of an issue when the deformation moves 90° and 70° together, but anything else and you will begin to see sharp edges in the geometry - not so good in an animation (unless its one about Picasso's cubist period).

Pentagon

Inevitably, you are going to get instances where five vertices converge (usually where limbs meet torso's, or where two pieces of geo meet), this is unavoidable, not ideal but tolerable. As the illustration demonstrates an equalateral pentagon consists of five converging edges, separated by 72°.  This amount is probably the smallest angle you'd wish to stretch to avoid those nasty tell-tale lines appearing in your geometry when your character bends over (imagine watching "Finding Nemo" and seeing loads of sharp edges appearing when the fishes start swimming. i don't think so!).

Hexagons's

In a tutorail I saw for Nurbs modeling It said pentagons were ok (by which I mean five converging verts) but not hexagon's. So what's so bad about hexagons? Well if you break it down in terms of angles, an equalateral hexagon will have interior angles of 60°. Going back to the equalateral triangle, it too has interior angles of 60°. So from a Mayan modelers perspective, a hexagon is just as bad as a triangle. Infact it's just six triangles placed side by side - six times worse.

The Golden Rule of Modeling

I think the general rule of thum is keep interior angles between 90° and 72°. Obviously this will be pretty difficult to do by eye (possible scripting opportunity perhaps??), but the experienced modeler would surely be able to develop an eye for it? When it comes to the crunch and you have 5 verts converging, keep the angles as near to 72° as possible, and keep the  joining verts close as possible so it's not spanning too greater distance - if necessary add an extra edge loop in to keep things local. These are the areas that will get the stick when it comes to moving and animating it around and those nasty non-planar edges will begin to appear, like a crack in the very fabric of your workflow!

If you have to use a triangle or angle thats less than 72°, make sure its in an area where its only going to collapse down on itself, and won't be visible when deformed, imagine the geometry performing the animation's its required to do. Still uncertain? Skin it, move it, and try weght paint out the nasty edges and angles; you'll soon discover its impossible! 

Nobody has ever explained why it is imporatant to keep things four sided. It's a very simple principle, if you stick to it, you can't go far wrong!

Crane Model

I've started to create a poly model of the Crane. My initial thought was to make it out of separate geometry, but having thought about it, I think i'll get a more realistic result if it was a skinned piece.

These images were rendered out using Maya Vector, with the edge options switched on to show the edgeflow. Some of the edges have not shown up but they do exist.

I've used the origami and Crane images as reference material. The wing will be setup using set driven keys so i'll be able to use the fk joint chain to make them fold properly.

I've gathered some reference material from the Internet, the brief is to create an origami Crane character that will be in-keeping with the rest of the animations oriental theme.

To achieve this look it will have to look like it's been made out of folded paper. I've created a few test renders to achieve this look by generating a uv map for a simple polycube. I've then scanned some patterned origami paper from Ed and some creased paper for an underlying texture. This will require a bit of playing around in photoshop to simulate a folded look. My initial thoughts having evaluated other origami images is to have separate segments of patterned colour juxtaposed against paper to create the illusion it's made from two different surfaces (front and back). Eddies kindly offered to scan in some origami paper samples to try out. The UV map needs to be easily transferable - one scene in the animatic features a number of cranes. I can easily duplicate the model I've made and make minor changes to the geometry, but it would be nice for them to have a variety of textures. I've thought about this issue and concluded that the UV map will have to be chopped up into different segments so the patterns can be over layed in photoshop with ease.

Another thing to consider is how the geometry is going to be layed out. Most origami images are shot from the side because they have little aesthetic interest from a front angle because they are flat and have no volume. TBoth Ed and I agree this model should have volume, so the body and neck section will be more bloated out than the images to make it look more interesting.
Also would be difficult to maintain control over deformations, so a bit of volume in these areas will help when it comes to skinning the character.

Left Giant Crane with lighting effects. Because the crane is made out of paper it will have to have an element of translucency. I've had a quick play with the transparency settings in Maya which gives a uniform transparency. Because paper achieves its translucency through perforation this will be incorporated into the texture.  

Origami Crane modeling reference

Great example of an origami crane, I've shown this to Ed and he agrees it is the sort of look we're after.

Nice pose it is pulling, I have gathered other pieces of reference material which show how the crane will be animated. This will affect how the models topology will be layed out.