Amapi 7 Pro Tutorial:

Building the Santa Maria with NURBS

Carl E. Schou

June 30, 2004



Santa Maria in Red

For this month's visit to the digital domain, we are going to build a model of Christopher Columbus' ship the Santa Maria, using the NURBS tools available in Amapi 7 Pro.  The image above shows the untextured model of the Santa Maria as seen in Amapi's modeling window.  We will start with a brief history of the ship and mention some sources for modeling reference materials, then present a strategy for building the ship with Amapi Pro's NURBS tools, before beginning the actual modeling process.

Some of the images used in this tutorial act as links to larger versions of those images.  If this larger image doesn't appear at full size, then let your mouse hover over the image and click on the magnification button that appears.



Brief History of the Santa Maria

The three ship fleet of Christopher Columbus set out from the port of Palos on the coast of southern Spain on August 2nd, 1492.  Columbus' flag ship the Santa Maria was accompanied by the Nina and the Pinta, and the total crew complement was 88 men.  After a brief stopover for repairs in the Canary Islands, the fleet traveled 2400 miles and arrived in the Bahama Islands on October 12th.  On December 24th, the Santa Maria ran aground on a reef along the coast of Cuba while being piloted in calm waters by an inexperienced ship's boy, and had to be abandoned. The timber from the ship was used to build a fort named Navidad and a garrison of thirty nine crew members were left behind to man it, since there wasn't room to carry all of the crew members back to Spain on the remaining two ships. When Columbus returned to the New World less than a year later, he found that the fort had been destroyed and there were no survivors from the original garrison.

No one is absolutely sure just what the Santa Maria looked like since there are no surviving building plans.  The Santa Maria is thought to have been approximately 80 feet long, 25 feet wide, and 200 tons.  Using written accounts of the day, together with illustrations from the time, the kind of ship has been narrowed down to one of two similar types, the Caravel, or the Nao.  The model covered in this tutorial is based on the Nao design.



Reference Material for Modeling

Probably the best source images of the Santa Maria are in a book that is now out of print, but available through online used bookstores such as Alibris.  The book is called "The Ships of Christopher Columbus", written by Xavier Pastor, ISBN 1-55750-755-4.  Information on Alibris, and sources for blueprints, are available in the Related Links section at the end of this tutorial.



Strategy for Building an Old Sailing Ship

(1) Research the ship you intend to build, get detailed images from several different views if possible.

(2) Build the hull from NURBS, taking advantage of symmetry and cloning.  In this case, the Manifold tool in Amapi 7 Pro is used.  NURBS surfaces of the deck, stern, and sides are created and arranged to completely enclose a volume shaped like the ship's hull.  The Manifold tool generates a 3D NURBS surface from this enclosed volume.

(3) Set the decks down slightly into the hull.

(4) Add the keel, rudder, railings, masts, and Crow's Nest.

(5) Build the sails from NURBS surfaces.

(6) Create the rigging for the masts and sails.

(7) Build the external structural support ribs for the hull.  These are cut from a duplicate of the hull to ensure that they follow the hull shape.



Build the Deck

To build the deck, select the pen tool and draw the NURBS line as shown below.  For sharp corners, use closely spaced control points.  For smooth, slowly changing curves keep the controls far apart.  To create the NURBS surface for the deck, make sure the top level of the Dynamic Geometry is active, select the Extrude tool, then click the curve and drag the mouse to extrude the surface out from the working plane.  You will probably have to press the space bar a couple of times to get the correct extrusion mode which keeps the extrusion size constant.





Build the Stern

The stern is built the same way as the deck, by creating a NURBS curve, then extruding it out as a surface as is shown below.





Create the Curves for the Hull

Using the Pen tool, create a line with 4 points as shown below left.  Switch to a top view and make sure the top level of Dynamic Geometry is active, then make six additional copies of the line spaced as shown below center and right.  Click on the image below to see the full sized version.





Apply Surface to Curves, Then Clone

Click the Ruled Surface tool, then click the top tip of each curve going from front to back.  Press Enter to validate and create the surface as shown below left.  Click the Symmetry tool with the option set to Clone to produce the other side as shown below right.  Note that the top level of Dynamic Geometry must be active to mirror the entire surface.  The bottom level was active for the illustrations so that the control points would be visible.





Move Control Points to Shape the Hull

Move the control points as shown in the next three images to approximate the shape of the hull.  The front end is completely closed, while the stern end is left partially open.













Combine Pieces and Apply Manifold Tool

Next, put together the Deck, Stern, and Hull pieces as shown below left in side, top, and profile views.  Make sure that the top level of Dynamic Geometry is active and that the surface normals of each piece are directed outwards.  This may be done by double clicking a piece to bring up its Information window, then clicking on Orient Normals.  The orientation may be changed by clicking the cube at the base of the Normal arrow on the piece in question.  It is also necessary to make sure that the enclosed volume is "watertight", meaning that there are no openings to the space that will be used to create the model.  If these things look correct, then click on the Manifold tool, click on each piece, and validate.  You should have a model similar to that shown below right.  Click on the image below to see the full sized version. 





Set Decks Down Into Hull

There are many different methods that may be used to recess the deck areas into the hull.  Since the model was going to be eventually converted to polygons, it was decided to tessellate the hull now, then recess the deck by manipulating vertices.

Select the hull, and convert it from NURBS to polygons by completely collapsing the Dynamic Geometry.  The resulting polygons are triangles instead of quads since the Crack Free NURBS option was chosen in the preferences.  Pull the deck vertices to outline the deck edges, then select and extrude the deck facets through the bottom of the hull using the Sweep by Block option.  Separately flatten the two sections of the deck by decreasing their vertical size.  Finally, move the deck sections back up into the hull as shown below.





Add the Keel and Rudder

Use the Pen tool to draw a closed outline for the keel as shown below.  Select the curve, extrude it out a short distance perpendicular to the working plane, then close the ends to produce the keel.  Use the same process to build the rudder.





Cut Slab for Rear Railing Base Object

Follow the process shown below to create a slab which will be used to create the rear rails.  Using the slab cut from a copy of the hull allows you to work with something identical in shape to the hull without having to worry bout damaging the original hull object.  Click the image to see the full sized version.




  Select the top edge of the rear deck slab and extrude it out a short distance with the Sweep by Block option active, then add thickness to the extrusion as shown below.  Trim off the downward curving tips, and you'll have a set of handrails that match the shape of the rear deck.




  Back at the rear deck area of the actual hull, add the vertical posts to support the railings as shown below. 




  Add copies of the railings to the posts.  In the image below, the position of some of the posts still needs to be adjusted.





Add the Masts and the Crow's Nest

Simple tapered cylinders were used for the masts.  The Crow's Nest was made by drawing a NURBS circle with the Pen tool and extruding it into the proper shape.





Making the Sails

The first sail was made by drawing a NURBS line with the Pen tool with four control points.  This line was copied three times.  A Ruled Surface was then applied between the lines.  In the Dynamic Geometry, the Ruled Surface level was collapsed to produce a NURBS shape.  The control points were pulled out to produce the sail shape in the images below.





Add the Sails to the Ship

Five sails were made by copying the original sail shape from the previous step.  These were individually shaped and added to the masts as shown below.  The triangular lateen sail on the mizzen mast at the rear of the ship required the most extra shaping.





Add the Main Mast Rigging

The rigging was made from long thin cylinders running from the side of the hull to the Crow's Nest as shown below.  A cube was added to the hull to act as an attachment point for the rigging.  The rigging for the right side of the ship was modeled first.





Mirroring the Rigging

The rigging on the right side of the ship was selected, then mirrored using the Symmetry tool with the Cloning option turned off.





Adding Rib Details to the Hull

Next we will create the support ribs visible on the outside of the hulls of many old sailing ships.  A copy will be made of the hull, and slabs corresponding to the ribs will be Boolean cut from the hull copy.  The ribs, which already follow the shape of the hull, will be thickened a bit, then added to the original hull. 

To make the horizontal ribs, a set of five curved NURBS lines were drawn with the Pen tool following the general curve of the hull copy when seen from the side.  These curves were extruded out from the working plane to create NURBS surfaces the same way that the deck and stern pieces were created at the start of the tutorial.  The same process was used to create the seven vertical ribs

The screenshots below show the horizontal and vertical rib slabs prior to being Boolean subtracted from the hull copy.




  After a little bit of thickness was added, the rib surfaces were Boolean intersected with the hull copy to produce ribs that fit the hull perfectly.  Extra thickness was added to the ribs to make them stand out from the hull a bit.  The ribs were then added to the original hull as shown below.





Add the Support Rigging for the Masts and Sails

Very thin cylinders were added to create the support rigging between the masts and sails.  In the image below, the main mast rigging we already created has been hidden for illustrative purposes.





Where Do We Go From Here?

At this point, we have a very basic model of the Santa Maria that has hopefully captured most of the essentials.  Parts that could be added to the model include flags and banners for the masts, ladders for moving between the deck levels, and an anchor to keep the ship in place.  After completing the modeling portion of the project, it needs to be exported for UV mapping, texturing, and rendering in a scene, but that's a project for another day.




Copyright 2004, Carl E Schou, All Rights Reserved