Car Modeling Using Nurbs Part 2


(Please read): During this part of the car tutorial we will focus on the front bumper and adding all the details.  To do this we will go over 5 tools: Offset Surface, Loft, Trim, Untrimmed, Round Tool, and Circular Fillet. The LFT (Loft, Fillet, Trim) process will be very repetitive and as the tutorial progresses you will become more efficient with the process.

1: Using Picture Reference

Start by going to the front view so we can start drawing our curve

2a: Front Curve

Draw a CV curve creating the desired shape.  Make sure to finish the curve right where it starts.  Once the first curve is finished, close the curve by going to Edit Curves - Open/Close Curve .  Once the curve is done, rebuild it to have a better distribution of the Spans (For the small curve duplicate the original curve and scale it to fid).

2b: Front Curve (Modification)

Take the smaller curve and move it back just as it is show in the picture, once you have reach this position - parent the small curve to the bigger curve.  Second step to do here is that you have to move the Pivot point to the left.  This is easily done by selecting your curve and pressing the Insert key on the keyboard now you can move the pivot where needed

2c. Front Curve (Modification)

Now rotate the curve so the two ends of the curve are touching your surface as you are working with the pivots, it is very important to know at what pivot mode you are on, make sure you are the Object mode. The best way to know is by pressing the keys W (Translation) and E (Rotate) on the keyboard.  As you are holding it down, left click and you will see a Hotbox menu pop out.  Here is where you will be able to see what mode you are on and at the same you can switch to a different one if it is desire

2d. Front Curve (Modification)

On pivot Object mode, move your curve away front the surface making sure none of the curve is penetrating with the surface.

2e. Front Curve (Modification)

Go to your profile just to make sure you have a nice clean profile and there is nothing that you are missing.

3. Loft

Now you want to loft your two surfaces go to Surfaces - Loft - loft options once inside the option menu go to Edit - Reset settings and then on Section Spans change the 1 to a 2 this will just give a better resolution, now select the two curves and press loft. This will become one of the most important tools since it is part of the LFT.  The tutorial will take some extra time at this point to go over some of features this tool offers, just to get a better understanding of the Loft tool.

4. Circular Fillet Options

Three things you know want to know when working with Circular Fillets.

1. When creating a circular fillet for trim purposes always use the Create Curve On Surface option ON, this option will make sure that a curve will be created on both surfaces used to create the fillet. The other two very important options are Reverse Primary Surface Normal and Reverse Secondary Surface Normal the mix of these two options are going to give 4 different results (See step 5c for more details), and finally Radius this options just gives the magnitude of the Radius, Self-explanatory.

2. A very import thing to have in mind is that this tool works based on Surface Normal so depending on where your normals are facing you will get a different result.

3. Every time you use this tool the best thing to do is to work with the Circular Fillet Options open that way if you don't like the results you can just undo and try a new combination of settings.

5. Circular Fillet

With the two surfaces selected g o to Edit Nurbs - Surface Fillet - Circular Fillet - Circular Fillet Options and having in mind what you learned in step 4 press Apply. The result you are looking for is a nice smooth transition from your bumper to the lofted surface

5b. Circular Fillet Options (Channel Box)

If for some reason you did not get it the first time, don't worry just select the bumper and on the channel box open the rbfSrf options here you will be able to make changes till you get what is needed.

2c. Circular Fillet Options (Options)

Here is an example of 4 different results that can be obtain by mixing these two options, please take a second to go over this image and see how images A, B, C, and D are all different just by changing the Primary Radius and the Secondary Radius numbers.  Don't forget this works under positive and negative numbers.

6. Trim

Select the bumper and G o to Edit s - Trim Tool the first thing you will see is that your mouse cursor has changed to an arrow and the second thing is that your surface changed to a white surface this means that it is legal for you to do the trim. Now select the part of the bumper you want to keep and a little yellow diamond will appear and press Enter on you keyboard.

7. Trim

Repeat the process on step six but this time uses the loft surface to trim.

8. Trim Results

With both surfaces trimmed, a nice circular fillet is our result. That is the complete process to create a trim surface. These steps will become very repetitive; if you can understand the process from step 3 to 7 the rest is going to be smooth sailing.

9. Bumper Curve

Let's draw the curve for your lower part of the front bumper

10. Loft

Duplicate curve and loft

11. Circular Fillet

Select the bumper, the loft surface and Circular fillet.

12. Move CV's

Sometimes the curve that is created from our circular fillet does not reach the end of our surface making it impossible to trim, but this can be fixed by selecting the curve left by the circular fillet and moving the CV's to the end of the surface till the CV's snap this will guarantee we have a legal surface to trim. Make sure to turn off surfaces so it will be easier to select the curves.

13. Trim

Now proceed to trim the bumper

14. Trim

Trim the lofted surface

15. Trim Results

That second part was so much faster than the first trim.  What we did at this point is more about how to layout the curve so we can get results we want.

16. Fog Light Curves

Create two circle scales and reposition them as shown.

17. Fog Light Loft

Loft the two curves.

18. Fog Light Circular Fillet

Use the bumper and the loft surfaces to create the circular fillet.

19. Fog Light Trim

Now trim the bumper and the loft surface.

20. Fog Light Results

Now we have the three basic trims

21. Duplicate Surface

Let's take our bumper surface and duplicate it.

22. Untrim Surface

With the surface go to Edit Nurbs - Untrim Surfaces. At this point we can delete the surface history just to make sure there are no extra nodes attached to our surface.

23. Offset Surface

Select the surface g o to Edit Nurbs - Offset surfaces. What we are doing here is making a uniform offset over the whole surface with the new surface selected go to the channel box and open Offset Surface and change the Distance to a lower number till you get something similar to the picture.

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24. Low Bumper Curve

Draw a curve to follow the lower bumper contour.

25. Low Bumper Loft/Circular fillet

Loft the curve and circular fillet, move the CV's if it is needed.

26. Low Bumper Trim

Trim and Bumper

27. Low Bumper Trim

Trim the loft surface.

28. Low Bumper Result

We created the second part of our bumper.

29. Bumper Results

Here is how it should look with the two parts.

30. Make surface Live

For this next part we are going to approach the making of the headlights.  To start the surface is not just going in one direction, it is going around the surface, making it a little trickier to do the trim. On this case we take our surface and we make it live (see next step for details).

30a. Make Live

Select the surface and go to the top, looking for a red horseshoe shape - click on it and automatically your surface becomes live, we know it is live because it will turn green. Now that our surface is live it will work as a magnet to the curve what we want to draw on it. Once you are done just click on it again to go back to normal mode.

31. Draw Curve on Surface

Following the shape of the headlight draw on the surface using your front and side view feel free to move the CV's around as well rebuilding the curve till you get the needed shape. Don't delete the history on the curve because we are not done with the curve yet.

32. Headlight Duplicate Curve on surface

With the curve selected g o to Edit Curves - Duplicate Surface Curve. Now it has made a duplicate of the curve but the different is that the curve is not constraint to the surface.This tool can also be used on isoparms

33. Headlight Move CV's on Curve

Offset the curve to find the profile, Take your time doing this, move back and forth between the two curves to create a clean loft. Once you are done with this part you can delete the history on the curves, Duplicate Surface Curve on the constraint curve and undo the live action.

34. Headlight Curve Result

Now we have two Curves one flowing on the surface and another offset to the surface but with the same number of spans.

35. Headlight Curve Loft

Loft the curves together, make sure you have a clean intersection between the two surfaces if it is needed move just a little the CV's of the surface curve away from the surface.

36. Headlight Circular Fillet

Proceed with the circular fillet.

37. Headlight Trim

Trim the bumper. Remember if for some reason you are not getting the trim it could be because you fillet curves are not reaching the end of the surface. Take a second to make sure the curves are at the end of both surfaces

38. Headlight Trim

Trim the headlights

39. Headlight Results

Wow that was a little tricky but we did it and here are the results. Not bad.

40. Front Details

For this part, start with a nurbs sphere with an end sweep of 90 and scale and rotate to find the shape. After that do the fillet and trim.

41. Front Detail results

Here are the results after playing with this part for few seconds

42. Extrude Curve Options

For this next part we are going to use the extrude a little differently. G o to Surfaces - Extrude - Extrude Options.   We are going to use the Distance settings, as soon you activate this Style a few things are going to change. Now we have a Extrude Length option, as well as, a Direction and a Direction Vector. Change your Direction from Profile Normal to Specify now Direction Vector is activated, Change the X Axis to Free this will turn on the input box, change it to -1 so it will go in a negative direction on the X Axis. Every time you see a vector remember that they are always laid out as X Y and Z in that order from left to right.

43. Extrude Curve

Select the last isoparm and extrude based on example 42

44. Round Tool

With the surfaces selected Right click and select isoparm two times.  This way both surfaces isoparms are active, after this just drag your mouse over the merging curves go to Edit Nurbs - Round Tool. A yellow handle will show

45. Round Tool Modifications

If you look at the end of the handle there are two little spheres grab one of them and drag it throws the center this will make the round toll to create a smaller tighter turn between the two surfaces .

46. Round Tool Channel Box

If you think the transition from one surface to the next one is too big or small, just go to the channel box - open the round tool and change the number till you are happy with the results.

47. Results

Here is a nice transition between two surfaces without having to trim.

48. Planar

Now just select the end isoparms for our two first trim and g o to surfaces - planar. This is going to create a trim surface to cover your holes for the lower part of the bumper just select the two curves and loft them together.

49. Front Bumper Results

Now that we know how to use Fillets, Trims and Round tools it should be pretty easy after this.

49. Front Bumper Results

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