Patrick Finn shows you how to use hard-surface modelling techniques to create a stylised mechanical bird
This tutorial will take you through the basic workflow of modelling a hard-surface object in Maya. Some of the tools may vary from software to software but the principles will still be the same. One element of realistic hard-surface modelling is that the object has generally been made or constructed, whether it’s a building, a car or a mechanical bird. This means that there has to be an element of precision to the work. It also needs detail, both in thought and production. It’s easy to lose realism if there are impossible things working together.
Poly flow is just as important in hard-surface modelling as it is in organic. However, where the aim is smooth animation in organic modelling, here the aim is adding this necessary detail while maintaining a smooth mesh without bumps or divots. There’s also a need to keep many edges quite tight, so extra edge loops are added wherever there’s a tight corner or hard edge. I won’t always mention this during the tutorial, but it’s something to bear in mind.
Get the supporting files for this Maya tutorial here.
First, you’re going to write some code to create a quad cylinder. It has the benefit of not having any triangles like its regular polyCylinder brother, while keeping poly count low. Once you move your model off-axis, it’s difficult to maintain precision, so you’ll model the body with the mesh on the horizontal axis, even though the final pose is tilted. You’ll then group all of the separate meshes together and rotate the group, rather than trying to fight against the software during the modelling process.
04:54: Create a quad cylinder
To create a quad cylinder, first you create a cube and add it to an array that will hold it for you. This means you’re not relying on using the object’s default name and enables you to create multiple quad cylinders without renaming them. Note that they aren’t single quotes surrounding ls –sl: they’re back quotes.
polyCube; string $selection[] = `ls –sl`;
Next, you select two edge rings and insert new edge loops in the centre of these edges:
polySelect –edgeRing 6 $selection; polySplitRing –ch on –splitType 2 –divisions 1 –useEqualMultiplier 1 –smoothingAngle 30 –fixQuads 1; polySelect –edgeRing 1 $selection; polySplitRing –ch on –splitType 2 –divisions 1 –useEqualMultiplier 1 –smoothingAngle 30 –fixQuads 1;
Once the edge loops have been added you need to select the four corner edges:
select –r ($selection[0] + “.e[4]”); select –tgl ($selection[0] + “.e[5]”); select –tgl ($selection[0] + “.e[8]”); select –tgl ($selection[0] + “.e[9]”);
Then you scale them in the X and Z axis:
xform –scale 0.7 0 0.7;
When Maya creates primitives it keeps them selected after creation, so you’ll stick with this procedure:
select ($selection);
Then you want to clear your array for when you create a second quad cylinder and need to ensure it’s a separate entity from the first:
clear($selection);
06:53: The inner skeleton
Create a quad cylinder, name it baseShape and add a central edge loop with Edit Mesh > Insert Edge Loop Tool > option box set to multiple loops, one loop. Tweak the shape to approximate the body shape of the bird. The basis of the skeleton is three pipes (Create > Polygon Primitives > Pipe). Combine them by selecting them and choosing Mesh > Combine. Extrude four faces from one of the end pipes and then merge the corner points to the corner of the equivalent faces on the middle pipe. Repeat this to join the middle pipe to the one at the opposite end.
08:17: Build the engine
Create another quad cylinder and scale it to fit inside the end pipe at the back of the bird. Extrude the centre faces inwards to create a smaller circle on the surface and then out to create a cylinder. Now repeat this process but with a smaller cylinder. This will act as a joint between the engine and the skeleton. Position this cylinder at the top of the engine and move its pivot point to the centre of the engine. Duplicate it and rotate it around the engine to create more joints.
12:41: Create cogs
Create one more quad cylinder and lengthen it to run throughout the interior. Add edge loops where the pipe joins the engine and in the centre of the pipe, and extrude the resulting faces.
For the cog, use a normal poly cylinder. Extrude the top and bottom faces inwards and then delete them. Add two edge loops and delete every other pair of the resulting faces. Use Edit Mesh > Append To Polygon to join the top and bottom halves of the cylinder. Select all of the faces on the outer edge and untick Edit Mesh > Keep Faces Together. Extrude these faces and scale them to a point in the X axis. You can then add extra details to the cog by extruding loops outwards or individual faces in. Duplicate the cog along the centre pipe.
14:33: Give the internal structure more detail
Add a quad cylinder in the middle of the first and perpendicular to it. Duplicate the cog and also rotate it 90 degrees. Position it so that it would be driven by a cog on the main pipe. Create some more joints like the engine joints and position them so that they join extruded parts of the central pipe to the skeleton.
20:30: Make a mechanical heart
Create a four-by-four plane in the Y axis (Create > Polygon Primitives > Plane > option box). In the top view add extra loops and then manipulate its shape until it resembles a heart. Extrude the outer edge outwards. Next, manipulate some of the points to create circles on the surface. Extrude these faces inwards to create better edges and then delete the faces. Now extrude the entire plane upwards and then duplicate it a number of times. On the two outer duplicates select the outer loop and extrude this upwards. Use another quad cylinder to create bolts around this loop. To finish, duplicate a number of cogs and position them so that they’re visible in the circular holes in the heart.
The sides of the bird are the first point where more flowing organic shapes are used. It’s important to keep the surfaces smooth and deliberate. It’s also crucial not to delete the history on your geometry until it doesn’t need to be moved again because you’ll be using constraints and projections to attach detailed geometry to the main piece of geometry. This is editable until the history is deleted, after which that relationship is lost.
01:07: Create the side piece
Select the faces on the side of baseShape and go to Edit Mesh > Duplicate Faces. Add some edge loops and make the shape more curved. Add a loop either side of the centre line both horizontally and vertically. Extrude the square that this leaves in the centre of the shape inwards and shape the points to make a circle. Check that the surface is still smooth as you move the points.
Now you need to extrude this circle in to create an indentation on the side piece. You can press the blue circle that’s just offset from the Extrude tool in the perspective window to toggle between world and object space. Flatten the faces in the Z axis in world space – this makes it easier to add secondary objects and detail. Video 2 02:57 Add extra objects to the side piece Next, create a quad cylinder and scale it to fit the indentation you just created. Extrude the front face and scale it to leave a small circle in the centre, then extrude this inwards to create a hole. Select the rest of the faces on the top of the cylinder and extrude those inwards slightly. Add edge loops and extrude the resulting faces back outwards to add some depth and detail.
03:32: Make the borders
Select the loop of faces around the centre circle and go to Edit Mesh > Duplicate Faces. Add edge loops around the edge of the entire side piece and duplicate those faces too. You can then extrude these two new objects. You may have to add more edge loops to the border around the whole piece.
07:01: Add detail to the side geometry
Select the edges you used to make the edge border and use Edit Mesh > Slide Edge Tool to move them closer to the edge. Add more loops to make the edges around the centre tighter, then spread these new points out to preserve the circular shape of your indentation. Select the faces that make up one quarter of the side piece at a time, and extrude them outwards. Now add more loops and manipulate the points so that the centre hole is more of a circle.
09:16: Add screws to the border
Create another quad cylinder and add enough loops to create a cross in the centre. Extrude this inwards and in the top view manipulate the outer edge of the cylinder to ensure that it’s circular. Add one more loop just under the top of the cylinder in the side view and extrude the new faces outwards to create a screw head. Select the border object then the screw and in the Animation menu set choose Constraints > Geometry. This attaches the pivot point of the screw to the border geometry. To ensure the screw faces the right way select the border then the screw and go to Constraints > Normal > option box. Ensure the World Up Type is Object Up. Duplicate the screw and move the constrained screw along repeatedly until you’ve worked your way around the border.
11:55: Create the twirls
In the side view create an EP curve (Create > EP Curve) and draw out a decorative curve. Continue doing this with new curves until you’ve covered one quarter of the side geometry. Now you can group these curves together and centre the pivot for the group. Move and rotate the group until it’s relatively close to the rotation of the quarter that you want the twirls to rest on.
With the group still selected, [Shift]-select the side geometry and in the Polygon menu set choose Edit Mesh > Project Curve On Mesh. In the option box you can select which plane the curves are projected from. Create a plane with no subdivisions and scale it down. Move it to the end of a curve by selecting the Move tool, holding [C] and middle-clicking on the curve. This is a little temperamental, though, so be prepared to move the plane to the end of the curve by hand. Select the plane, [Shift]-select the curve and extrude. The number of divisions defaults to 1, so open the channel box and in the inputs list you’ll find the last polyExtrude. Scroll down to Divisions and increase it. If you have multiple curves that you want as one mesh, select the face nearest the start of the second curve. Repeat this process for each curve.
This section combines the techniques of the previous two. Some processes may not be explained in detail and you may need to refer back to the first sections to follow along. The base or front of the bird is where a lot of the detail will be, though, so it’s worth spending the time on it and getting it right.
01:49: Make the base
Select the bottom faces on baseShape and go to Edit Mesh > Duplicate Faces. Add some edge loops and make the object more curved. Extrude some of the central faces and scale them in. Extrude them in, making an indentation in the surface. Now create three more cogs from normal cylinders using the process from the first video.
06:52: Detail the front
Once there are three cogs, duplicate them and arrange them in the indentation. There has to be a central pole holding the cog in place so the centre of a cog can’t be placed over another cog. Create a cube and scale it so that it’s nearly flat. Add extra loops and move it so that it covers the cogs at one end of the indentation. Manipulate its points to create a curved front. Add three edge loops in both X and Z directions and create a circle in the top of the cube. Extrude this circle downwards and place another cog there. Create another thin cube and place it above this cog. For more detail add a cylinder that joins this to the centre of the cog.
08:56: Add joins for the cogs
In the top view go to Create > EP Curve and create curves from the edge of the indentation to the centre of each cog. Once you’ve created all of your curves create a plane and align it to the start of a curve. Select the plane then [Shift]-select the curve and extrude. Increase the number of divisions in the channel box or attribute editor if you need to.
15:18: Detail the joints
Once all the planes have been extruded, ensure that the end of each extrusion is over the centre of a cog. Add an edge loop lengthways and another that crosses the last face only. Manipulate the points of the last face into a circle. Extrude these faces inwards, then down and then back. Add an edge loop either side of the centre edge loop. These loops go through the circles you’ve created, so delete an edge from the loops on the top and bottom of the mesh, just before the circle. Delete the portion of the edge loop that runs into the circle. Now use Edit Mesh > Interactive Split Tool to join the loose ends of the edge loops back to the centre edge loop.
In order to maintain 100 per cent quads you can then select the edge on the centre edge loop that lies between the two edges you’ve just created and go to Edit Mesh > Delete Edge / Vertex. Then select the faces either side of the centre edge loop and extrude them. This process needs to be repeated for all of the curves that you created.
I’m only going to go through the work on one side of the head. With objects that are separate you can group them, duplicate them ([Ctrl]+[D]) and scale them to a value of -1 in Z to make sure the model is symmetrical. For the head itself, because it has a centre line you can select the faces on the unchanged side, delete them, select the mesh and go to Mesh > Mirror Geometry > option box, making sure you’re mirroring across the correct axis.
05:13: The head shape and the eyes
The modelling work on the body is finished, so move it to its final pose. Select all the objects and group them, then rotate the group to its final position. Create a quad cylinder and move it to the end of the body. Rotate the mesh around to fit with the angle of the body, then select the top faces and extrude them outwards, rotate them to a more vertical position and then extrude again. Repeat this a couple of times and on the last two extrusions also scale the faces in.
Choose some faces on the side of the head that will make up the eye, extrude them and scale them inwards. Move the verts to create the desired eye shape. Extrude the faces that make up the eye, scale them in and then extrude them into the head. Select the loop of faces just outside the eye and go to Edit Mesh > Duplicate Faces. Extrude this new object to make a border around the eye. Create a cog (using the techniques in the first video) and place it in the centre of the eye.
09:08: Model the beak
To create the beak, select the faces on the front end of the head and scale them in so that they’re thin and tall. Extrude them and scale them in, creating a hole for the mouth. Select the loop that you created, duplicate the faces and extrude this new object. Now select the faces in the back of the mouth and choose Duplicate Faces. Duplicate the object and delete the top half on one and the bottom half on the other. Extrude these objects outwards and shape the upper and lower beak.
19:48: Create the armour
Select the faces between the lower eye loop and the horizontal centre line of the head and duplicate faces. Extrude the object and place one end into the border around the mouth and the other into the border around the eye. Create a cube and scale it so that it’s thin in the Z axis, shape it like a triangle and add enough vertical loops so that it can curve around with the head. Starting in the corner between the mouth and the mouth and eye join, duplicate this cube and move it further towards the eye. Make it touch the head at the top and looser at the bottom, and repeat around the eye. Create a plane and shape it around the bottom half of the beak. Mirror to make the plane curved underneath the beak. Add an edge loop at the bottom, select the new faces and extrude.
Once you’ve got to the other side of the eye select an entire loop of faces around the neck and duplicate faces. Again add a loop at the bottom and extrude. Line up this neck plating with the pieces going around the eye.
The tail and feet are a little more mechanical. They’re two parts of the bird that would have to move if this were a real mechanical creature. A mechanical bird wouldn’t necessarily have to fly, so the wings can be a little more decorative.
02:54: The basic tail mechanism
Create a pipe the same size as the rear pipe on the internal skeleton. Make a cube, add edge loops and extrude faces to make an elongated C when looking from the front. Duplicate this cube and use the two to join the internal skeleton and the new pipe. Now create a quad cylinder and scale it to act as a bolt between the two.
07:41: Add the feathers
Create a quad cylinder and make a smaller replica of the engine in the first video. Centre it in the pipe for the tail. Duplicate the joints between the engine and the skeleton. Create a quad cylinder, scale it down and rotate it so that it’s coming out of the old engine and facing down towards the new one. Duplicate the cylinder so that you have a core of four or five cylinders. Now create a cube and scale it so that it resembles a thin triangle. Extrude the top face in and then down, creating a ridge around the edge. Create another quad cylinder, elongate it and move it so that it’s joined with the thin end of the poly triangle you just made. Duplicate a number of these mechanical feathers and move them to finish off the tail.
12:47: Build the feet
Create a quad cylinder and position it at the base of the bird, as a hip joint. Select the bottom faces and extrude them firstly in and then downwards. Create a second quad cylinder and rotate it 90 degrees in the Z axis so that it’s across the first. Extrude both ends to create the button effect used before. Create a cube and add a number of edge loops to make circular holes. Manipulate the points to make the circles and then delete the faces. Fill in the holes with the Append To Polygon tool. Duplicate the object and create another bolt to join the two together.
For the feet, create a cube and add some loops. Scale the middle loops in on the Z axis. Ensure there are enough edge loops down the Z axis to create two claws at the front and one at the back. Select the faces for the claw and extrude out a few times, scaling down as you do. Group the leg objects and mirror or duplicate them across to the other side.
17:42: Create the frame for the wings
First, create a quad cylinder, scale it down and position it so that it emerges from the hole in the side of the bird. Create another quad cylinder and extrude the top faces in. Move the points so that they’re in a more rectangular shape and extrude in.
Next, create a cube and scale it to make a plank shape. Place it so one end is in the rectangular hole you’ve just made and the other end emerges upwards. Move the cube’s pivot to the end nearest the bird’s body, and duplicate and rotate it to face downwards. Add another curved cube between the two. Add two more planks that join the ends of the two straight planks you created to the far end of the wing. Tidy the places where all of these objects come together. Create a quad cylinder and make a small bolt, then duplicate the bolt wherever two or more planks join.
23:54: Finish the wings
Go into the front view and create curves for wherever you want some detail. After completing the curve swirls, create a plane, align it to the base of the curves and extrude. For the lower half of the wings create a cube and shape it so that it’s similar to the tail feathers. Create one long version for the back of the wing and one shorter version for the front. Finally, duplicate these along the length of the wing, adjusting the rotation as you do.
Patrick Finn is a freelance Maya generalist. A background in scripting and maths led to him working with MEL, Maya’s dynamics system and its modelling toolset
Posted on Thursday, August 30th, 2012 at 2:12 pm under Guides, Technique, Tutorials. You can subscribe to comments. You can leave a comment, or trackback from your own site.
Tags: Maya
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