We’re going to repeat many of the previous steps, except, this time, we’re going to reuse Curve1 and Curve2 where they are, and either modify Curves 3 or recreate it. We should still have the remaining portion of Curve4 to use for the back part of the tail. Since we’re reusing curves, we’ll need to delete tailFront’s history. Select it and go to Edit > Delete By type > History. Now, any changes made to the curves will not affect the tailFront surface.

Modify Curve 3 to flow along the contours of the backside of the tail. Make sure that the ends are curve snapped to the corners of Curve2 and the curve left over from detaching earlier (Fig 26).

Now, the only curve we really need to rebuild is the left over curve from earlier. In my example, it has 7 spans. Because the curve opposite of it (Curve2) has 10 spans, I’ll rebuild this curve to also be 10 spans. Again, create a boundary surface. You should get something similar to Fig 27. Rename the surface to tailBack.

Now that we have our surfaces and their geometry is suitably efficient, we can delete tailBack’s history (Edit > Delete By Type > History), and delete our curves. Select both tail surfaces and Rebuild with optimization settings:

• Parameter Range: 0 to #Spans
• Direction: U and V
• Keep: CVs

After rebuilding, we’re going to check the number of spans in each and ensure that their surface directions match. If you have followed along, you may come to a situation similar to what I have. Your numbers may vary. The spans for tailFront, in my example, are 10 in the U direction and 7 in the V direction, while the spans for tailBack are 7 in the U direction and 10 in the V direction. The directions are opposite of each other. This is a very easy thing to fix. Select the tailBack surface and go to Edit NURBS > Reverse Surface Direction > Options. In the options, Edit > Reset Settings. You’ll see a “Swap” option. Select it and push the Apply button. You should notice that the Spans UV of tailBack switch from 7U-10V to 10U-7V. Now both have 7 spans in the V direction, which is the direction we’re going to attach the two surfaces together.

With both surfaces matching in number of spans and in surface direction, RMB on each and select “Isoparm” from the menu items that appear, putting both surfaces in Component Mode. On tailFront, select an isoparm and drag it to where the two surfaces meet. Hold the Shift key and click and drag an isoparm on tailBack to the same location. This action selects two isoparms right on top of each other where we want to connect them. With the two isoparms still selected, go to Edit NURBS > Attach Surfaces > Options. In the Options, Edit > Reset Settings. Make the following Changes:

• Uncheck “Keep Originals”
• Make sure “Blend” is selected

Once attached, rebuild the surface with optimization settings and delete its history. You should end up with a result similar to Fig 28. Save your scene as sharkman4.mb.

We’ll attach the tail to the body the same way we attached the two halves of the tail together. Again, we need to check the number of spans and surface direction of the two objects. Your numbers and surface directions may vary. In my example, the body has 24 spans in the U direction and 17 spans in the V direction. My tail object’s spans are 20 spans in the U direction and 7 in the V direction. We need to make sure which directions need to attach. RMB on the body and select “Control Vertices” from the menu items that appear. Look for what’s in Fig 29. You’ll see that instead of the normal points, the surface direction is indicated with a small U and V. It may be easier to see in Wire Frame Mode (“4” key). Here are the directions for the tail: Fig 30.

Hopefully, you can see in these two images, the directions are opposite of each other. Select the tail surface and Edit NURBS > Reverse Surface Direction > Options. Make sure “Swap” is selected and reverse. [Note: Your surface directions may not need to be fixed.]

Now, my body surface’s directions are 24U-17V, while my tail is 7U-20V. We’re going to rebuild the tail to match the body in the V direction. So, select the tail surface and go to Edit NURBS > Rebuild Surfaces > Options. Instead of the Optimization settings, make the following changes:

• Parameter Range: 0 to #Spans
• Direction: your direction (V in my example)
• Number of Spans Direction: number of spans in the body (17 in the V direction in my example)

Now, RMB on each surface and select “Isoparm” from the menu items that appear. Both surfaces will be in component mode. LMB on an isoparm on the tail and drag it up to the edge where it would meet the body. Hold the Shift key and select and drag an isoparm from the body to the edge where it would meet the tail. With both isoparms selected, go to Edit NURBS > Attach Surfaces > Options. Make sure that “Keep Original” is un-checked and “Blend” is selected. Apply. Rebuild the new attached surface with optimization settings and delete its history. You should end up with a surface similar to Fig 31. Save your scene as sharkman5.mb.

Create a NURBS sphere (Create > NURBS Primitives > Sphere). Make the following changes:

• Translate X: 2.7
• Translate Y: -0.9
• Rotate X: -1
• Rotate Y: 4.5
• Rotate Z: 64.6
• Scale X: 0.5
• Scale Z: 0.2

You should result with something similar to Fig 32. RMB on the sphere and select “Isoparm” from the menu items that appear. Select the isoparm near the body and Edit NURBS > Detach Surfaces. Delete the small portion at the tip (Fig 33). RMB on the sphere and select “Hulls” from the menu items that appear. Translate, Rotate, and Scale the hulls; insert isoparms; push/pull CVs; and rebuild with optimization settings until you get a shape similar to Fig 34. My example ended up having 5 spans in the U direction and 8 spans in the V direction.

Here comes another long one! :)

In this step, we’ll begin the surface patching involved to merge appendages into NURBS creature’s body. You may need to insert some isoparm in the body in order to build up enough density to achieve sufficient patches. After inserting isoparms, make sure you Rebuild the surface using optimization settings.

Patch modeling is a very time consuming and tricky procedure, and I would highly recommend saving your project file before this step in case you find that you need to re-attempt it, so save your scene as sharkman6.mb. Also note that your numbers and surface directions may vary.

The first step in creating a stitch is to detach the body horizontally where the flipper will merge into (Fig 35). You may need to adjust the position of the flipper for an optimal angle.

In order to frame the stitching from the rest of the model, we’re also going to detach one isoparm above and one isoparm below our initial cuts (Fig 36).

Select two vertical isoparms to detach on the first surface. Delete the resulting square piece of geometry (Fig 37). Select and detach the vertical isoparms on the second set of cuts that frame the boundary of the hole (Fig 38).

Next, select four isoparms on the flipper that coincide with the four corners of the hole and detach them (Fig 39). Select all of the surfaces and Rebuild with optimization settings and delete their history.

Now, we’re going to make sure that the pieces that are going to connect together have matching spans and surface directions. Select the top flipper surface. In my example, it has 5U-2V. The small surface it is going to merge into (Fig 40) has 1U-3V. It is the V directions that are going to attach, so we will rebuild the top flipper surface to be 5U-3V. In the Rebuild Surfaces options, make the following changes:

• Parameter Range: 0 to #Spans
• Direction: your direction (V in my example)
• Number of Spans Direction: your number to match (3 in the V direction in my example)

For the next pair of surfaces (front flipper and front body), you may get the situation I have in my example. The front flipper surface has 5U-2V, while the front body surface has 2U-9V. As seen in Fig 41, the directions that match with 2 spans are the ones to connect, yet they are in opposite directions. As was the case with the tail fin, we will “Swap” the directions in the front body surface, making it 9U-2V. As the two surfaces match in number of spans already, no rebuilding is required. The same situation is for the back flipper and back body surfaces. You may need to “Swap” the directions of the back body piece. The bottom flipper piece and bottom body pieces are matching in direction, but not in number. So, rebuild the bottom flipper piece to match the number of spans as the bottom body piece (3 in my example). Once all the surfaces have been repaired to match in surface direction and number of spans, select all of the surfaces and Rebuild with optimization settings and delete history.

Now, we’re going to begin filling in the hole to merge the surfaces together. I find it easiest to enter wire frame mode (“4” key) and to lower your surface’s resolution (“1” key). The method we are going to use is the Fillet Blend. Go to Edit NURBS > Surface Fillet > Fillet Blend Tool. With the Fillet Blend Tool active, select the isoparm of the top body surface and press ENTER. Then, select the isoparm of the top flipper surface and press ENTER. You should see something similar to Fig 42. In my example, the surface twisted. This is fine, as it is easily fixed in the next step. Go ahead and select the isoparm on the front body piece and hit ENTER, then the isoparm on the front flipper surface and hit ENTER. Repeat for each pair of surfaces. You’ll find that two of the fillets twist (sometimes three), while the rest remain straight (Fig 43).

To fix the twisting, you simply select the body piece the fillet is attached to and go to Edit NURBS > Reverse Surface Direction > Options. In the options, try reversing the body surface’s direction in either the U or the V direction. If one does not work, simply undo (“Z” key) and try the other direction. Once the twists have been repaired, select all your surfaces and Rebuild with optimization settings and delete their history (Fig 44).

Next, we’ll attach the fillets to their respective flipper pieces. RMB on both the top fillet and the top flipper surface and select “Isoparm” from the menu items that appear. Both surfaces will be in Component Mode. LMB on an isoparm on the flipper and drag to the edge where the two surfaces meet. Hold the shift key, and click and drag an isoparm on the fillet to the edge where it meets the flipper. Edit NURBS > Attach Surfaces > Options. Make sure “Blend” is selected and “Keep Originals” is un-checked. Apply (Fig 45). Repeat for each pair of surfaces (Fig 46). Select all, Rebuild with Optimization settings, and delete their history.

Now, we’ll attach the four surfaces of the flipper together, using the same method. You’ll notice, as you attach them, they pull away from the body, leaving gaps in the corners (Fig 47). This is fine. After attaching three corners, you’ll find that you cannot attach the fourth corner using the same method (Fig 48). This is because you are no longer attaching anything. After attaching three corners, you result in one surface. In order to finish the blend, select the surface and go to Edit NURBS > Open/Close Surface > Options. In the options, Edit > Reset Settings. Make the following changes:

• Shape: Blend
• Surface Direction: Try one, if it doesn’t work, undo, and try the other.

Once complete, you should have something similar to Fig 49. Once again, select all, rebuild with optimization settings, and delete history. Before continuing, you will want to take notice as to where your flipper’s seam is (Fig 50). The surface’s seam is a darker, thicker isoparm than the rest. This is where the surface’s texture will begin and end and it can be difficult to hide the texture seam. Therefore, it is usually a good idea to put the seam in a little-seen location. To do so, simply select the isoparm that you’d like to make the seam, and go to Edit NURBS > Move Seam.

Now, the final step in stitching the flipper to the body: the Global Stitch. Select the surfaces involved (Fig 51). Go to Edit NURBS > Stitch > Global Stitch > Options. In the options, Edit > Reset Settings. Make the following changes:

• Stitch Corners: Closest Knot
• Stitch Edges: Equal Params
• Stitch Smoothness: Tangents
• Modification Resistance: 1.0

Hit “Global Stitch.” Now, once the stitch has taken effect, press Ctrl + A to open the Attribute Editor. The Editor will open for the Global Stitch. You’ll notice that, in my example, the stitch did not close all of the gaps (Fig 52). In the Attribute Editor, slowly raise the Max Separation slider. In my example, at a value of .158, the surface snapped together, blending into the body (Fig 53). Select all your surfaces, rebuild with optimization settings, and delete their history.

If for some reason the raising the Max Separation slider does not complete the merge as you’d like, try checking the “Stitch Partial Edges” box and trying the Max Separation slider again. If it still does not merge correctly, you can attempt to try some of the other settings, such as the Stitch Corners and Stitch Edges pull-down menus, but if you are not able to get it as you’d like, the only thing I can recommend doing is starting again at your previous save file before attempting the stitch. The reason why, is that the stitch depends a lot on which isoparms you initially select to detach. When you try again, try to use different isoparms that perhaps will give you better results.

With the flipper successfully stitched, and its surfaces rebuilt to their optimization settings, and history deleted, we can continue. Save your file as sharkman7.mb.