Building a biped character copyright Giulio Porta 2002. All rights reserved.



Our goal here is to construct a character figure using the least number of points. The idea is to put it together as quickly as possible, reserving details for much later. I urge you to use the same number of control points as I have used here in this illustration to your right.

Hit the # 5 key on your keyboard to work in a top view (Z and X plane), you will build your character cross contour at the waste line or there about.



Group all the 10 points and Extrude them, the extrusion may not occur in the desired direction, because the software does not know what you are doing,  just grab the bounding box by clicking inside of it and drag it up, do this in a side view. 

Repeat the operation 8 times, that will give enough cross sections for the torso, from the bottom of the pelvis, to the top of the neck.

These extrusions do not have to be done sequentially. You can stop regroup cross sections, move them up and down and go back to the top or bottom row and sweep again.

At this point what you may have will not look like a torso, feel free to use a rotoscope image.

You could start editing the cross section before the torso is complete:
  • drag the points at the bottom of the pelvis downward
  • group and narrow the waist.
  • move the point above the navel up some, that will be the bottom of the rib cage, the end of the sternum.
Continue to extrude three more cross sections all the way up to the neck, and scale down the neck some, don't make too thin or too thick, if you are really uncomfortable with all this, you must use a rotoscope image, some from an anatomy book will do.
Look at your torso from the side, key # 4 on you keyboard, you'll notice that your torso has the personality of a bowling pin, because no adjustments have been made to the side view.

You'll need to define the anatomy a little bit better.

  • Get rid of the hump below the neck
  • Group the points at the top and the bottom of the neck and rotate them forward.
  • Get rid of the hump in the back by the shoulder blades.
  • Arch the back
  • Flatten the belly
  • Push out the buttock
  • Use a rotoscope image from an anatomy book, if everything else fails, or you can simply use what I am doing here as a guide line.
Look at your work in the round to spot potential defects.
The next step is that of adding legs. You'll need to bridge the bottom of the pelvis first, so to create two openings, one for each leg.

You can get the leg started but don't be in a hurry to attach it, until the bottom of the pelvis is complete.

If you are working in Shaded/Wireframe mode, your patches will turn into polygons, this is only because the Shaded mode drivers do not support patches.

Group all the points that make up the pelvis area and make everything else invisible. The grouping should be done in a front view for a clean a precise selection.

Ad a total of four new points and bridge them with three splines. 

First select the segment to which you want to attach the new point and press the Y key on your key board to ad a new point, do that 4 times, adding two points in the front and two in the back. After you have bridged the bottom of the pelvis you should have a shape that looks like an underwear.

The very front and rear patches will be now 5 points, you'll have to group them and click on the 5 point patch icon to maker those patches solid.

Next, group the splines that make up the two holes where the legs will be attached, switch to the top view and edit the control points to make them as round as possible.

Start a new circular spline with the SAME NUMBER OF POINTS for the cross contour of the leg.

Extrude the leg cross contour a few times, group all the control points at the top of the leg and with the Rotate tool (R) rotate that group of points to angle it like the hole at the bottom of the pelvis.
Keep extruding the leg, which should be as long as the upper half of the body including the head.

The knee area should be place about at half way the leg's length.

From the side view, # 4 or 6 on key numeric key pad, group the lower half of the leg and move it back to simulate the arch that the lower leg may acquire when weight is placed on it.
Go on to sweep the foot, obviously from the side view.
From a top view widen the foot. and point edit it, so it will look close to a normal foot, one with a sock on. Close the front of the foot with one vertical spline.
Select one segment from the top of the leg and press the comma (,) key on your key board, the entire top row of splines will be selected.

Press the Delete key to delete the top row of splines so to leave just dangling splines, to be attached to the pelvis.

Copy and paste the leg before you attach the one you just made.

Pick the best possible view and zoom in to perform this operation, but first let's copy the leg.
Use Ctrl + C copy and Ctrl + V to paste the leg, next flip it with the Flip command along the X axis, Right + click on the screen and select Flip > X Axis.
Group both legs and rescale them to the right proportions to the body
For the arm, draw out a 6 point spine and close it, you can do this in the front view and rotate it to the side view or directly in the side view.

The arm can be scaled to the body's proportion later.

Sweep the arm as many times as you see here, and rescale the cross sections to conform to the arm's anatomy.

Human/humanoid biped models are constructed with their arm out horizontally because they are easier to construct, the Bones can be inserted in them more effectively, and the the Bone's handles can be adjusted without having the torso in their way.

The arm is made out of 6 points but the hole that it is going to be inserted into is only 4. You will need to make two 5 points patches to dead end 2 of the six splines, one into the torso the other on the opposite side into the back.

It is a good idea to break the neck spline, which currently runs down to the torso, and make it continue toward the arm instead.


Copy, paste, and flip the arm.
Break and repatch the shoulder/ neck spline so it will continue toward the arm and not down to the torso. Create the 5 points patches as necessary to close the holes in the shoulder.
To close these holes with a 5 point patch, you should group the front part of the torso and make everything else invisible, do this for the back as well, that will make the 5 points patching easier.
You are just about finished with the model, with the exception of tweaking (point editing) the model to perfect its form.