Making of: the process of modelling and rigging a Mechanical model

[3dpoder]

making of: the process of modelling and rigging a Mechanical model
By Robert burke.



Introduction i have ben working on this model for some time now and rather than repeating the usual step by step tutoriales, y have decided instead todo write a brief article. The article Will detail the process and a few of the techniques used todo get from the first idea todo construction of a complex Mechanical model that could be animated, todo the finished excavator.

As with any Project the first stage is planning, and as this was a learning exercise todo get todo grips with Blender animation tools, y had todo choose a machine that had a lot of moving parts. The excavator fit the Bill perfectly.

Now knowing what i was going todo model, it was time todo go of and find reference materiales. A set of plans would be useful, but unfortunately none were available on the usual plan repositories. However, the manufacturer did have some reasonable side, front and rear views in their pdf literature. They didnt exactly scale th rouge from one view todo the next, but a Little adjustment in Gimp got them near enough todo be used.



Besides the plans, Google was useful for finding photographs, and whilst passing a near by construction site, an excavator was parked alongside the fence allowing me todo have a close up look at the machinery. Setting up plans in Blender is quite a simple process, y usually work from thre 3d views and toggle the active view todo full screen with Control-down arrow. As i only had a front, bak and side view of the excavator, these were set up.





To set up the views, in the 3d view Header click view>background image and from the background image window load the front view. To help align the other views drag a plane so the Edges touch the extremities of the excavator front view. In the next 3d window load the bak image and then use the x offset, y offset and the size controls in the background image window todo scale and align the image todo the Edges of the plane. For the front view you Will ned todo rotate the plane 90 Degrees on the z axis and align the image only todo the top and bottom Edges.

Before i set about modelling the excavator, y thought it would be useful todo make sure i could get it todo anímate. To do this, y Simply traced the arms and buckets using Bézier curves and used these as simple 2d Cut-outs todo help position the armatures. The piestons and cilindros used simple track todo constraints with their ends parented todo the respective component, in this case the cylinder todo the arm and the pistón todo the fulcrum. The process is described really well in the Blender 2.3 guide and is still relevant todo the current versións of Blender.

It should be stressed that pivot and rotation points must be accurately set and aligned using Blender Snap tools. The bucket movement was a Little more complicated than a straight armature chain, requiring both ends of 3 Bones todo be set todo fixed locations. This was achieved by adding an armature object at the pivot point of the fulcrum and parenting it todo the arm and snapping the other end of the bone todo the pivot point of the connecting rod. Another bone was extruded from this point and snapped todo the interconnection between the connecting rod and bucket. Then a third bone was extruded and snapped todo the pivot point of the bucket. An Empty was a los added todo the pivot point of the bucket and parented todo the arm, so the Empty would move in relation todo the arm movement.



The fulcrum was parented todo bone 1, the connecting rod parented todo bone 2 and the bucket todo bone 3. The trik todo getting this type of mechanism todo work was adding an IK constraint todo bone 3 with the target set todo the Empty i had placed on the bucket pivot point, with use tail selected in the IK constraint.



The two unused axes of the Bones were disabled in the armature Bones panel, allowing the Bones todo only rotate on the one axis. To animate the bucket movement now only required bone 1 todo be rotated in pose mode and all the other components would follow.

The front mechanism used a similar setup on both the front bucket rotation and the top cylinder fulcrum. Satisfied that the process of animating this machine could be accomplished, it wastime todo start modelling.

Precision modelling tutoriales, you should be familiar with all the tools and techniques neded todo create any Mechanical models. In fact its Even simpler todo create a model for animation, as it only neds todo be a representation of the real thing and not a CAD perfecto 3d reproduction.



The process is therefore Simply a matter of tracing áreas of the model from the background image in one view and then pulling the vértices todo align with the corresponding point in the perpendicular view. The job is made Even easier because the tractor unit and front mechanism is symmetric between the left and right sides, so only one side neds todo be modelled with the other being created using a mirror modifier.



On complex models, working component by component can be a lot less daunting than trying todo build the whole model as one Mesh.

Once comfortable with the process described in the precisión modeling tutoriales, it should become quite straightforward todo build large complex models from numerous components. However being able todo animate those models means you ned todo be Fairly strict in the bien you name each component and in the structure of how they are parented todo each other. The mirror modifier was a useful short Cut for modeling, but can cause some problems further down the line on this Project, so i applied the modifier once the modeling was finished.



With the basic model completed and all the parts parented todo either the armature systems or the main body, it was time todo start adding details.



Moving hydraulic components ned hydraulic fluid todo be pumped th rouge them, so this necessitated pipes and hoses. Pipes arent a problem because they are static Items in relation todo the components they are attached to, but hoses ned todo Flex and move with the animation.

I experimented with a number of methods todo achieve this, but found you could obtain a very realistic movement using just curves, hooks and empties. What more, you can set the end tangency of the hose so it doesnt rotate at the end point. I Will write the method up as a mini tutorial sometime in the future.
With a few more details added, it was time todo se how this model loked in a render. Basic materiales were added for the paintworque and a highly reflective material added todo the hydraulic pistón todo simulate the Ground Chrome material. The model was then positioned on a plane which was curved at the bak todo simulate a Studio bak drop. Two área lights were added together with a light behind and above the model reelative todo the Camera.



In order for a reflective material todo look god it must have something todo reflect.

A basic reflection map was created by placing a UV sphere inside a box together with a few props todo simulate a Studio flash brolly. The UV sphere was set todo the máximum reflection and an image renderer of the sphere. This was then used as an angle map in Blender world settings.



The end result was a Fairly convincing image of an excavator, though, given time, the image could be improved considerably. This isnt the end of the excavator Project, i now ned todo UV Unwrap the model and add some realistic textures, then set the model in a construction scene. All that, however, is for a future date and i Will mensaje further información here when it is completed. I hope you have found this run-th rouge of the Project useful.



By Robert burke.
www.blenderart.org.