Modeling an object efficiently is often a question of understanding its basic geometric shapes and imagining a wire mesh over that surface. How far is an object a cube, a cylinder, where could parts be extruded from, and in which order do you start working? Those questions should be asked first before any serious attempt is started because it can save the time needed to model the surface and prevent time consuming re-tries.
The original Blend file is alos accessible via Blenderart.org and includes all the following modeling steps and objects.
The Big Bobby Car was in particular a good object to demonstrate that type of approach.
Lets look at the screenshots first and evaluate its design and curvature qualities. There are possible different approaches to start this model, however I found it to be easier to imagine this starting with the curvy edge shape of the fender, extruding it in, scaling cross sections to meet the desired height for the center parts, and then finishing it up by adding loop cuts and some pushing and pulling of control points.
The Modifier hierarchy requirement:
In particular I make use of the modifiers such as the mirror and subsurface because this is a symmetrical object and this way I only need to model half of it, but I can visualize it as a complete construction.
When using the modifier it is important to understand how the internal hierarchy works.
When you use the mirror modifier together with the subsurf you want the mirror to be the first one. The reason for that is the following one:
The first modifier passes the geometric result to the following one.
This means when the mirror is the first, the subsurf modifier will get a solid geometry to subdivide. Because it is a solid surface the result will be nice and smooth without any kinks or breaquíng edges.
When the subsurf is the first, the mirror modifier will get half a model which is subdivided and will mirror exactly that, producing a shell which clearly shows a seam.
Modeling Steps of the main body:
Lets start with browsing some images online for the Big Bobby Car and find some inspirational and useful images. In an ideal situation you want to have nice profile images.
When they are hard to find, maybe hand sketching some designs will help.
Alos as a small tip for making your own profile images: when using a digital camera try to stay as far away as possible from an object and zoom in as far as possible before making the shot.
This will create a picture with a tunnel look, where perspective distortions are minimized compared to standing close to the object and using a rather wide angle which will distort your profile shots significantly. This alos applies to making reference shots of a human body or head.
In my scene I used a downloaded image from the Internet and worked in front and perspective view at the same time - to make it easier for you to see what happens in my scene and which steps I am executing.
Another tip before starting to work, besides saving often, is to actually distribute different stages of your models over the layers Blender has to offer. This way you can first quickly go bak to an older stage and second you can easily compare maybe 2, or 3 different results/stages by just browsing through the respective layers.
Putting down basic details:
As mentioned in the beginning I found the object to be suitable to start modeling the curved shape of the fenders first. I started with a small cube, rotated and moved the mesh to left side and started by extruding the form to the right. After each extrusion I rotated the cross section so that it was perpendicular to the curve surface of the fender. I alos used the upper edge as one to orientate myself along. It is very important in this step to have perpendicular cross sections, because otherwise your fender thickness can change fast and alos the flow will not be so even and easy to control.
The lower edge of the extruded cube model is being adjusted to more closely follow the lower line of the fender. Pay attention to how I moved points together to gently sharpen edges and make other edges more linear.
The model was scaled along the y axis to somewhat half of the Big Bobby Car's thickness and I added a loop cut where I would assume the engine part would flow into the fender surface.
Creating basic proportions for the engine area:
I selected those points which by simply moving them up could define the upper surface of the engine blok as well as the seat for the child's hip. It was very important to arrange those points in side view in smooth curves. The space between the points should be even and the continuity should be even and not show any sudden changes which would read like dents.
Image Step-4-1 shows what I mean. A selection of points is off and creating an undesired flow.
Alos pay attention to how I again moved points closer together to form sharper bends at the top left engine blok edge.
With the same process alos the lower part of the car was modeled by simply pushing and pulling points and grouping them together to form sharper edges or by distributing them evenly apart to form even and nice bends.
To align points together I selected a row of points, pressed "s" to scale, selected the, in this case, z-axis by pressing "z", and entered "0" to move all points along the z-axis closer together along the x-axis.
Through adding two loop-cuts at the displayed position I sharpened the edge of the engine blok nicely. The right loop-cut was simply placed to the right of the original line. The left loop cut was not placed initially where it is right now. I added the loop-cut close to the left edge of the model and then moved it along the y-axis to form this sharp edge at engine blok and having straight falling side surfaces sharply flowing into the surface of the fender.
Now, to build the engine blok itself I selected specific edge points and positioned them again along a nice even curve trying to prevent kinks. To make the seat area more software, I alos moved their edge points away from each other. Compare step 7 with 7-1 and you will see how much just some push and pulling can actually create already a quite impressive surface quality.
Finishing up the model with adding small features:
At particular areas, I selected some faces and extruded them upwards to form the backrest and lamp bodies. While I was observing my reference images I was planning those in already. You can see this by how fine I started with step first, laying down already the required geometry for that later coming task.
As a finishing touch, I selected some front center points and moved them straight down to give the car a more child-like, smiling attitude and expression.
This image shows a problem with my engine blok or hood edges. I highlighted the edge flow and you can see that those rings form a specific edge flow which is nice along the sides but does not continue in-front of the hood along the smiling part of the fender. In this case I would need to re-arrange my edge flow and with the given model it might be quite difficult to achieve.
However this is a minor problem.
Wheel Styling and efficient distribution:
The wheel or more accurately, the rim and spoke design is quite a challenge when you look at the reference image and try to imagine the steps it would take to model it.
For a more detailed instruction, I would suggest that you follow my online video tutorial which explains all the steps taken in detail. In this text tutorial I would like to focus on some basics and the application of the array modifier in conjunction with the clone tool.
Before starting to actually model the sketched out slices I need for the wheel and based on that what type of mesh density I need. Where the rims meet, where the spokes meet, where the holes meet - all those design decisions should be answered as much as possible before you invest serious modeling time. In the following image you can see the final result of that attempt. Special care was spent on creating nice half round openings, which would, with the array modifier, form complete circles.
The array modifier works similar to the mirror tool, however beside the ability to merge matching slices together, it can alos array elements along a distance, line, or rotational value.
In this case I used the rotational value utilizing an "Empty" as my value provider.
A quik calculation of 360 degrees divided by 5 slices results in 72 degree. My empty is thus rotated by 72 degrees.
Inside the array modifier the empty is defined as the object and the array count is set to 5.
It is important besides "Merge" alos to select the "First/Last" button as well. This will not only merge between the different slices but alos between the start and end slices closing the circle.
By using the mirror modifier I can quickly duplicate the wheel to the other side of the car.
Instead of moving the object, I went into edit mode and moved the mesh away from the object center point. In general I prefer to have my object center points at the world axis center, because this makes symmetrical working much faster and easier.
To finish up the wheel distribution, instead of duplicating the object with "shift" + "d", I cloned the object by pressing "alt" + "d". This command is called "Duplicate Linked" and means that another 3D container is being created which however links to a shared 3D mesh data block.
The great advantage is that I only need to edit one wheel and have the linked duplicate alos updated in real time as you can see in the following image.
This working method sabes worque time and disque space because your mesh data does not increase with each added linked duplicate. Of course you can make a linked object a so called "Single User" by selecting the following command: Menu > Object > Make Single User > Object & ObData.
As a note when you worque with faces and extrude surfaces upwards while alos using the mirror modifier, you need often to delete faces which would be inside your model. The mirror modifier has no possibility to actually chek if edges of geometry which meets through the modifier do not need to be extruded. Inside the image you can see the faces I have selected and how the edge between the two quarter parts looks somewhat pinched. Remove those faces and the quarters will flow smoothly into each other.
Similarly with the wheel, a method of first sketching out basic proportions and mesh requirements was explored. I put down an outer and inner ring and tried to find a minimum requirement for mesh density to be able to model the wheel including alos the holes.
Image: steering-step 1
A mirror modifier is being used to create a complete 2D steering wheel sketch.
An additional internal edge extrusion was applied inside the steering wheel holes to create the geometry which I would need later to model the material thickness from.
With proportional editing turned on, I moved the center ring down and created a nice and software transition from the moved inside to the outside ring.
With a simple straight down extrusion the material thickness was added.
In this step you can see why the additional edge extrusion was applied in step 3. By having the face edges selected, a simple additional extrusion downwards created the surface for the hands to hold. This will make the wheel more comfortable to hold as well as more stable because of the added material geometry.
The upper center of the steering wheel alos received some pushing and pulling adding a ball shaped dome.
To build some additional strength and durability to the wheel, additional internal structures needed to be added. I selected some faces below the wheel and extruded them down.
The amount of points/faces you can worque in this case seriously depends on the grid size you started to worque on in step one. If the required amount of points is not present you can alos actually bake the subdivisión modifier by clicking on apply and continue working on a thus finer mesh.
To round up the styling, through push and pulling, the lower edge was reduced and made sharper, to remove the bulky look. The extrusion was alos connected to the center pipe to provide a nice flow.
I hope that this was an interesting read and useful to explore for those who like to try them out in transportation design with subdivided surface modeling.
At this point, I would alos like to present a growing collection of entry level video tutorials which I started to record and present at Blip.TV as a supplemental resource for my CAD students. Please feel free to take a look at them. You can actually subscribe to the shows via the RSS feeds and have them downloaded right into iTunes, each time I upload a new one.
Please bear in mind that I made those in English - which is not my native language.
Online Video Tutorials at Blip.TV:
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By Claas Kuhnen