Car Body - General Shaping
Now we get to the more interesting parts. Up until now, we've spent a lot of time just making a box with a ragged polygon structure. Boring as that was, it was the foundation for everything else... and our success at that will determine our success at the outcome of the model.
You may have had trouble following my reasoning (I'm not sure I follow it myself sometimes!), or you may have missed a cut or two in the confusion... I'd like everyone to be able to follow along with the tutorial, whether they missed a step or not. So, in the spirit of sportsmanship, if you had trouble with the dull parts, you can download a scene file with the precut cube here!


Download cutcube.c4d here in zip format or sit format.


Shaping the Side View
First of all, we can delete some polygons that won't be necessary. Select these polygons from underneath the front end, and also near the back end and delete these. You can see which ones have been selected in the following three views.
Note: Once you delete polygons, you can switch to point mode, select all, then run the optimize command with the unused points checkbox checked. This gets rid of all the points that were left floating around aimlessly after polygon deletion.



Before we get started on the shaping, setup the car object with a symmetry object parent, and then throw the symmetry group underneath a HyperNURBS object. Here's a look at the hierarchy structure, along with the settings for the symmetry object.










So with any luck, we've managed to get to this point. Looks like a car already, huh? No? Okay then...
Interestingly enough, the HyperNURBS is smoothing polygons in such a way that the loosely defined wheel wells are almost close enough to our reference picture to need very little modification later on.
That won’t always be the case, but we’re certainly appreciative when it is!




For now, we can be content with the approximation of the car's body shape. When we add detail in the upcoming steps, we'll be making the slope of the hood more accurate, and adding the swells and tail fins according to the reference image... The wheel wells are close, but a starting point only. For now, it is best for us to leave them a little bit off, but still maintain the straightness of the grid. If we find we need any knifecuts we didn't anticipate, It will be a lot easier making cuts that go straight through the grid without worrying about crossing polygon edges and triangulating the mesh.
To continue on with the shaping of the side of the car, let's look next at the top view.




Shaping the Top View
From the top, we can see we don't have to do much in this case to get close to the body shape, which is fairly rectangular to begin with. All we have to do for now is move a couple points to define a slight change in the curvature of the front quarter panel, where it swells to accommodate the shape/styling of the headlights. Also added is some curvature to the hood and trunk.




These points take relatively minimal movement. I should point out that when using the point tool to select these points, make sure you consider whether you want the "Only Select Visible Elements" option checked in the active tool menu. In the above cases you will want to select more than just the topmost point, so make sure the option is not checked.





Shaping the Front View
The front view at this point is looking just like we want it to (I hope!!!) However, we can take the time to select the points on the lower part of the body and slide them over, so that we will have a nice gently curved look to the side of our car.
Later, when we add detail to the headlight area, you will see we want to extrude a round shape from a square polygon formation. For that reason, we won't want too irregular of a shape in the upper corner there... best to leave it square until we have our full attention on it.






Shaping the Door
Back to the side view! Here we are going to shape the front edge of the door to the curvature indicated by our reference picture. It's merely a matter of selecting the appropriate points and repositioning them. Make sure you select all points in their "clusters". Remember how the door edge is defined with multiple knife cuts? To make the point manipulation quicker, you should select each little group of points and move all edges at the same time.






Don't worry about getting 100% accurate on the placement of either the door or cab edges. Since we are working from hand drawn reference pictures, we can always blame the artist who drew them if we find our model too inaccurate! ;-)

Shaping the Cab Edge
This is another exercise in grabbing point and pulling. I hope you get to like that because we're in for a whole lot more!!! Again, 100% accuracy is not mandatory... whoever drew these reference pictures is clearly a lunatic! :-)






Deleting Polygons from the Cab Opening
Now to 'cut' the cab opening from the top of the car, we can select the polygons that are currently skinned over where we want our cab to be open, and delete them. It is important to note here which polygons are being selected, as we made those double knife cuts along the edges for a reason. We want to retain the tight polygons in areas where we are still requiring a hard edge!
Have a look at which ones should be selected and the result in deleting them..








Well now! As basic shaping goes, that's certainly a basic result... It's on the way to looking like a car, though!
Next, we'll get into some intermediate detail...

Car Body - Adding Detail
Page 1 - Headlight Swells

Even though the planning stage was still the most important, now we get into the meat and potatoes of the model. Without adding detail, it was just a well planned model of a box. Now we have to bring the actual car model to fruition. Herein lies a lot of manipulation of the model at the point and polygon levels. I hope you're seated comfortably, this may take a while!



There's a reason why we kept that frontal headlight are as square as possible.... ummm, you did didn't you?
First we want to define the headlight housing. (Forgive my lack of knowledge of car anatomy!!!)







Select the four polygons up front where the headlights will go and extrude inner three times. The first extrude inner sets up the surrounding swell, the second sets up a 'transitional area', and the third defines the shape of the headlight.
Because of the interpolation of HyperNURBS, the more square this area is, the less we have to adjust to make round lights.



Select the inner ring that we will turn into our actual headlight housing. A series of simple extrudes will bring this area bulging out like we want. One small extrude to create a tight fillet, one lengthier extrude for the main shape.







Notice the very thin extrude creating the tight fillet between the protruding surface and the main body.
It's not as round as we'd like, but that's due to the unavoidable polygon density in this area right now. We'll MAKE it round via point manipulation.





Select the points at the top, bottom and sides of this extruded segment. Make sure you select all the points on the extruded piece, right back to the car surface.
If you just select the outermost, you'll end up only affecting part of the shape.





Activate the scaling tool, and constrain it to only affect the X and Y axes.
Using the scale tool, drag until the points drift out enough that the protrusion resembles a roughly circular shape. It likely still won't be satisfactorily round (unless you are doing better than me!)




Now we do the final tweaking to the roundness by selecting the points on the corners of the protrusion and adjusting them as necessary to achieve an overall circular shape. Again, depending on the level of accuracy you're aiming for will determine how much time you want to put into point pushing!


At a passing glance, that's round enough for most purposes, so we can move on.
We've only just begun...

Car Body - Adding Detail
Page 2 - Headlight Swells

It's always nice adding the detail to a basic model shape... There isn't much gratifying about building a model until it starts to look like you intended! Therefore, continuing on right where we left off...



The outer square created by the first in a succession of three extrude inners in our previous step is for defining the lip of the swell. That forward sweeping stylish element common to a lot of 50's era cars.
Select the polygons in the top half of that extrusion







Using the move tool, simply move them along the Z axis, straight out from the surface of the car.
















It's a start, but it's still really square. So how do we fix? Point manipulation!!!
(Did I just hear a groan?)
Select the points on the upper corners as shown.



Using the scale tool constrained to the X-axis, you can move (scale) these points inwards towards the center of the swell to eliminate at least some of the squareness.




Now, using the same method, select the points on the side of the lip of the swell.
Also note that some points are selected a certain distance back into the body on the outside above the wheel well. When these are included the result is to add a bit more of an even curvature from body to swell.



You can see the result of adding that extra curvature to the side of the body.
This swell is getting a lot rounder, but it still needs some work up top.



Select the points at the top of the swell. And similar to the previous step where we included the side of the car body in the points we manipulated, this time we'll tweak more of the top.
Include about two or three points back along the top of the swell.



Enabling our reference picture once again, we can move these points in such a manner as to match up to the curvature indicated in our side view.
Don't worry about including all points along the swell all the way back yet. Just take enough to distinguish the area we are working on.







We can see from the perspective view that although that helped the top of the swell curvature, more work must be done to achieve the right shape on the lip above the headlight.
Select the topmost polygons on the front surface of the lip.





From the side view, move those polygons forward in the Z axis direction to fill in the shape of our reference image more closely.





It's coming along nicely, but that's still an awfully fat lip!
Select the bottom point on the top of the lip edge, and we'll move it in such a manner as to tighten that ugly bulge up.




Like so.
That's a fairly decent lip now. I don't think the headlight rim there is in the most accurate spot however.
The best thing about HyperNURBS however is the adjustability! In the next step, we'll rework the rim to finish the headlight region - for now!

Car Body - Adding Detail
Page 3 - Headlight Swells

This segment of adding detail to the headlight swells is a little bit of reworking to enhance the accuracy of an earlier step. Nothing major, but it is a good example of how versatile a tool HyperNURBS is. If an element is not exactly where you determine it should have been, rather than deleting and remodeling, there is always the chance that some simple modification will be sufficient. That should be the case here, as I move the headlight protrusion into a more accurate position under the lip of the headlight swell.



That headlight protrusion/rim ...( I resist calling it the headlight as it defines the shape of the rim only and will be replaced by advanced detail later on)...is seated awfully far back and well below where I believe it should be.

To make it look more natural, we'll bring it out and up a bit.

If we'd saved the rim polygons as a selection set, we'd be laughing here... we could just restore the selection. That's something you may want to get in the habit of doing... saving selection sets of key elements you suspect need further manipulation... I didn't do that here though, so I took the extra time to re-select all pertinent polygons that make up the rim.




Move the polygon selection along the Z axis with the move tool, so is just short of being flush with the edge off the upper lip.






Now we can finalize the positioning by moving the selection up on the Y axis so that it rests just below the lip above it.












The area surrounding and below our headlight shape is still very flat, and needs to be improved.
Here we select the points responsible for adding a little bit of curvature out of the flatness...






...and move it outwards along the Z-axis to create the roundness.





The points indicated are somewhat misplaced as well in the new look. To avoid pulling down on the shape of the headlight in this "frowning" manner, we'll select them and move them into a more natural position.











Just moved enough so that it keeps with the the general shape of the surface and doesn't visibly disrupt the contours like it it did before.









Moving beyond the bounds of the headlight swells, we can modify the curvature of the rest of the front end of the car.
Select the bottom point in the middle of our front fender, and move it outwards along the Z axis.




Additionally, select the point defining the edge of that fender curvature (as shown), and move them along the Z axis towards the body.




This increased the curvature considerably, and also should have the added effect of blending the bulge into the lower front/grill area a lot more evenly.



That concludes the light detail for now. We've still got plenty to do to achieve a final result, but luckily it gets WAY easier from here on in...
Haha!!! Just kidding! It doesn't get easier, but it does get more complete... so let's continue.










While we're down in this area, we may as well add a little bit of a lip where the front of the car body will slope down in behind the bumper.
Simply select all the polygons along the lower front edge.


Next, make two knife cuts fairly close together a small distance up from the very bottom of the front edge of the car.
These cuts serve as the anchor point for the transition from the vertical face of the car front to the slope we will make.


If we had only one knifecut in this situation, the transition would be more gradual and far less angular.
However, since we aren't looking for a completely amorphous shape, we need a bit of sharpness...


Simply select all points along the bottom of this edge now (leaving the bottom point by the wheel well unselected).
Then move the points away from the car body along the Z axis until it looks right.

Car Body - Adding Detail
Tail Fins - Page 1

In our previous step, we adjusted the curvature of the top of the side panels of the car. As the panels progressed to the rear of the car, we just left off finishing the back end so we could devote our attention to the tail fins separately. Now has come the time to tackle those fins.








Initially, before the fin gets underway, it's as good a time as any to advance the shaping of the rear end of the car. In our reference picture, we notice there is an upward slope beginning just behind the wheel well and rising up to where the bumper will be.
The easiest way to do this is to just select all points that make up the bottom edge of the back of the car and move them up (constrained) on the Y axis until the slope matches the reference picture in the side view.
To the left you can see the before/after in perspective view.







Judging by our reference picture, the base of our tail light is supported by a protrusion that almost resembles an hourglass in profile.
(Actually, the reference picture isn't that clear, but I have other info, so you'll just have to trust me!!!) :-)
The two polygons that make up this portion of the back of the tail fin aren't much to work with, but with some creative poly modeling, we'll do okay...





Select the aforementioned polygons (shown at left) and extrude them a small amount away from the back of the car body.
Don't worry about the softness of the extrusion... it's of little consequence right now.





Keep the polygons selected.
Select the scale tool, and with scaling constrained to the Y axis, scale down the polygons to approximately half their size.
The scaling operation seems to occur around the midpoint of a selection (as do other operations such as rotate, etc.).
That is okay, it just means we'll have to worry about placement after the scale operation.





Keeping the polygons selected, now select the move tool and move the polygons upwards on the Y axis.
Try to line them up with the top of the polygon on the side of the car so that a "shelf" is made.
The shelf is still very loose and organic, but gives a good basis for improvement.





Select the rotate tool and rotate the polygons on the X axis so that they 'tip' away from the car in a downwards facing manner. Ideally, you will check the angle you want to match on the reference picture (side view) and rotate the polygons accordingly.
Because the rotation occurs around the selection centerpoint, adjusting the placement of the polygons may be required. Just use the quick move handles to reposition then quickly.





Now select the bottom pair of polgons (right below the two previously selected).
Use the extrude tool to extrude and move these polygons a distance away from the back of the car.



Keep the same two polygons selected.
Select the rotate tool again and rotate the polygons on the X axis so they tip the opposite direction in an upward facing manner.







It will be necessary to adjust the positioning of these polygons to match the shape of the reference image in the side view.
Use the move tool to draw these polygons in closer to original formation.



That gives us the geometry we want on the back of the car, but does little to define it sharply enough. We will have to flatten the 'shelf' and tighten up the surface to make it appropriately accurate.
And we will! Next page!

Car Body - Adding Detail
Tail Fins - Page 2

In our previous step, we managed to get some rudimentary geometry set up for the addition of our tail fins. Now we'd like to refine those humble beginnings into some recognizable auto body stylistic elements...



There is a slight 'separation' occurring between the hourglass shaped 'shelf' for the tail light and the tail fin. This is due to the fact that two separate extrusions were made from two different sets of polygons. To get the edge between them sharply defined, we are going to resort to point manipulation on the most basic level in the next step.
I can hardly wait!!! :-)






The first order of business is to remove a little bit of the width from the protrusion we modeled previously.
To taper it, we can select the polygons that make up the face of it, and using the scale tool constrained to the X axis, scaling it down to about two thirds the original width.



The bottom curvature is still a little on the extreme side.
Switching to point mode, we can further reduce the width of this portion by selecting the bottom three points and further scaling down (using the scale tool again with X axis constraint).






















Here the points are simply brought upwards on the Y axis to improve the shape to personal taste.
The shape matches the side view reference fairly closely now.




The 'shelf' on which our tail light will eventually sit is still very loose due to the amorphous nature of HyperNURBS.
To sharpen it up appropriately, all we need to do is select the two polygons that will form this shelf...



... and then perform a VERY tight extrude inner.
Just move the mouse very minutely with the extrude inner tool active. The result will be a sliver thin row of polygons surrounding the two selected polygons.
Sliver thin polygons can make for some really tight HyperNURBS edges... just make sure to remember those slivers are there in the future!



Moving up to the actual fin, we have to increase the influence the control cage has on the underlying HyperNURBS model, that way the fin will be able to 'fill in' the shape we need it to (in order to match our reference).
Select the polygons that will make up the back of this fin.



Perform an extrude on these polygons. How far you extrude doesn't much matter, since the final positioning of the polygons will have to be done after the polygon rotation in the next step. (Remember how polygons will rotate around the selection centerpoint... this makes rotating something into exact positioning unlikely, and almost guarantees a certain amount of repositioning.)



Rotate the selected polygons on the X axis so they tip back in a downwards facing manner.
Reposition the polygons (with the move tool, or move handles) so that the bottom edge of the slanted polygons more or less occupies the same edge as the shelf edge.




A fairly tight extrude inner further influences a sharp edge out of the back of the tail fin.
There is a slight 'separation' occurring between the hourglass shaped 'shelf' for the tail light and the tail fin.



Except for the fact that I just found the tail fin shape too wide and rounded at the top.
In an effort to add some 'pointiness' to the tail fin, The points that influence this curvature can be selected and scaled inwards on the X axis.
This brings the point closer together, and makes for sharper curvature on the top of the fin.

Car Body - Adding Detail
Tail Fins - Page 3

By now, our tail fins are looking pretty nice, but are just a little bit light on believability. The 'separation' occurring between the tail fin and the shelf for the tail light might be okay under some circumstances, but for the car we are modeling, it is not as accurate as I'd like. There should be a better blend occurring between the two elements. Now we will go about adding this blend.
Note: I have hidden the polygons that will make up the trunk, for viewing clarity in this step only. You have not missed anything!!! (Just in case you were worried!) ;-)








The first thing we will need to do is to get rid of some of our problem polygons.


Since we are manually 'mending' this tail fin area in this step, we will be welding vertices together to make a more efficient cage. However when we streamline the number of vertices, we will end up with extra polygons. To avoid confusion, it's best to just determine which ones are unnecessary and get rid of those.


Now we have a clearer idea of what needs to be done when we look at what's left.





The general idea now is to move all of the points from the tail fin to match exactly the positions of their corresponding points on the shelf area. As you can see, the shelf points are highlighted green in the picture, while the tail fin points are highlighted red. What you want to do is use numeric entry via the structure manager (in point mode) to match coordinates of red points (A, B, C, D, & E) to the positions of the green points (a, b, c, d, & e).
Just so there's no confusion, 'A' should match to 'a', etc.!!! (Like instructions on shampoo... sigh...) :-)








To the left I've shown a couple glimpses of the technique in action as the last couple of points are matched up. In the bottom picture, all are matched except the final z coordinate which is highlighted blue (about to be entered). Luckily my points were close enough on the structure menu I didn't have to go scrolling too far to see my target coordinates. Sometimes it's good to have a piece of paper and pen handy for this though...
Note: I suppose you COULD have matched up points from the shelf to the points on the fin (opposite to what I described), but then you'd have to adjust the flatness of the shelf again by moving all the points back down into position...




So now we can see that we've got a very sharp edge between the two elements, which might be acceptable...
...other than the fact that it creates an unsightly 'kink' right below the edge along the side of the shelf.
...And the fact that the points are occupying the same place, but not joined. They very easily could split apart if we were not careful...








The left picture shows the result right after the optimization. Because now there are suddenly less points & polygons defining the same shape, the shape becomes immediately looser and more amorphous again. Don't look at that as a step backwards! It's not... Merely select the inner polygons of both the shelf faces and the fin back face (leaving the edge polygons untouched), and use the smooth shift tool to create an inset. Just smooth shift a small amount to get a sharp lip... or smooth shift minutely twice in succession to get a really sharp edge.
Notice also that because the edge polygons were left out of the smooth shift operation that there is a slight curving blend between the fin and shelf elements... That was very fortunate, as it brings together the elements naturally and completely reverses that separation effect we were looking to eliminate!





In that case, what we'll do is select all the points (make sure that both points of each 'pair' of points occupying the same coordinates are selected).
Then use the optimize command to make the selected points 'weld'.
Two points within the specified tolerance become one point...


One caveat with this step, is that the optimization of points the way I have described has led to a triangle polygon right on the side of the fin. Earlier, I mentioned that triangulation was bad and should be avoided.

Now I must admit, that sooner or later, I inevitably end up with at least some triangles. I try to keep them off to a relatively harmless location though. If you look at the wireframe, you can see what sort of affect this triangle has on the distribution of the detailed mesh. It is somewhat irregular, but with only one tri, it is fairly minimal, so I'm not overly worried.

I think the main problem involved with triangles is that they can lead to irregular shading properties, and of course the mesh distribution. But also I imagine that this can have a negative impact on the UV of the mesh, making it difficult to texture under some circumstances.






However, the fact that this is a car body and shouldn't require complex UV mapping (most likely it will end up with a basic paint shader covering the entire body) I really don't see this triangle being anything to worry about. Depending on how adamant you are against triangulation in your HyperNURBS mesh, you may decide to rework the point or polygon structure to remove this and stick to quads only... (However, then you are on your own!) :-)
The rest of us will be enjoying the next step!

Car Body - Adding Detail
Hood

We're getting close to the end of the body shaping. One of the major parts that we do have left however is the refinement of the hood and trunk. Turning our attention to the hood now, we are going to add some slope to it, and then separate it from the main car body. (We will discuss adding the appearance of thickness to the car panels later... this enhances the realism of the car, but will also enable you to "open" doors and hoods and trunks later, should the need arise.)









When we raised the center line of the top of the side panels to create the curvature our reference pics demanded, we created the need to modify the height of the cab edge.

The cab edge sits almost flush with the top of the side panel. Also the trunk and hood slope down and away from the elevated cab edge to the back and front ends of the car respectively.

We will correct the height of the cab edge and add the starting point for the slope of the hood by selecting all the points that make up the edge of the cab (around the front, sides and rear of the cab).

Make sure to select point pairs in places where our cab edge was defined with a double knife cut.
Then using the move tool, move them upwards on the Y axis until they are in place (top curvature of the door softens).