Martin Davis wants to animate some realistic creepy-crawlies; Glen Southern comes riding to the rescue
Find the supporting files for this Cinema 4D Q&A here.
The latest version of Cinema 4D has a powerful set of rigging tools. You can find lots of examples of characters rigged and animated using Advanced Biped, but how do you cope if you need to rig a non-humanoid model – an insect or spider, for example? Well, there are more rigs available to you than you may think, right out of the box. Along with Advanced Biped, you can find a basic biped, bird, fish, quadruped, reptile, and the one I’m focusing on here: the insect rig.
In this example I’ll create a robotic ‘spider’. I used basic box modelling to create the creature. It’s not accurate to spider anatomy because I only used six legs, but it gives the desired look for the project. I used cubes for the head, thorax and abdomen, shaping them into a rough approximation of spider anatomy, then added spheres for eyes and a few gun parts for the underside of the head. I only made one leg, which again started from a cube. I used reference photos to get the anatomy of the leg correct and then extruded the cube and shaped the joints by adding loop cuts. Once I’d made one leg I copied it twice and then aligned all three to the left side of the body. I then mirrored the three legs over to the other side. I decided to make a single mesh for the spider, so I selected all the parts and used connect and delete.
With the spider model selected, I added the character object from the top menu. You start with the Build button selected. This gives you all the options you need to start rigging your creature. Change the drop-down menu in the character object to Insect and you’ll see the first option to add a thorax. With the thorax in place you can see the next set of items to add. Add an abdomen and a head for now, then click back onto the thorax and add some legs. To do this symmetrically, hold down [Ctrl] and you get a leg on both sides of the spiderbot. Do this twice more to give it six legs.
Once you have all the correct parts for your spiderbot, click the next tab after Build, which is Adjust. You can now see a representation of where your joints are placed. Using the Move tool, simply move all the coloured circles to match your creature. Wherever possible move them inside the mesh. If you don’t, you can end up with all sorts of binding issues later on. Try to look at your creature from all angles to get this adjustment correct. The legs will work symmetrically so you only have to adjust one side, which is a big help. Once everything is lined up, move to Binding. Select the spiderbot mesh and all the rigging under the character object and hit the Bind button in the Character menu.
This should bind all the joints to the mesh and automatically weight the rig for you. If you’ve matched your joints to your model well you should be good to go, but you may need to go into the Weight Painting tool and adjust them a little.
Once the spiderbot is rigged you can try it out with a little walk cycle. Move to the Animate tab and choose Add Walk. If you’ve done all the steps above correctly, then when you select Play, your spider will do a little walk cycle on the spot. To get it moving draw a spline in the top view. You’ll see a CMotion object in your hierarchy. Click Object and then change the drop-down menu from Static to Path. Drag and drop the spline into the dialog and the spiderbot will follow this spline when you click Play. There are many more options to choose in CMotion, so you can spend time configuring your creature to walk just how you want.
Weighting the model
Sometimes the auto rigging doesn’t bind the joints to the model correctly because the weighting isn’t right. Select the model, then go to Character > Weight Tool.
Paint the weight
Painting weight adjusts how much influence a joint has on a part of the mesh. Using the painting tools you can increase or decrease the effect.
Adjust each area
If a leg has too much influence over a part of the body, simply select it and paint out the offending area – or add more if needed. Hold down [Ctrl] to remove painting.
Glen Southern is a freelance 3D artist with over 15 years of industry experience in film, TV and games. He’s also the owner of SouthernGFX
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Posted on Monday, September 10th, 2012 at 3:15 pm under Guides, Technique, Tutorials. You can subscribe to comments. You can leave a comment, or trackback from your own site.
Tags: Cinema 4D R13, rigging
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