After having positioned your corner control points and shaped your edges, it is now time to shape the internal surface. It is at this stage important to force yourself not to make any more changes to any control point that is either a corner control point or located on an edge. If you think back about the analogy with the painter painting the portrait, you are now probably at the stage where you have positioned the object (the person) on the canvas with the right size and proportions and sketched the outlines or contours. From here the painter can fill in the rest of the portrait in any order and again each painter will have his personal preferences.

You can chose to change the position of the internal control points using any random window in any random order, but from the author’s experience a good efficiency can be achieved using the Windows in this order:

1.      Body Plan

2.      Plan or Profile

3.      Perspective

Also don’t forget that modelling in 3D is an iterative cycle and you will cycle through steps 1 à 2 à 3 à 1... several times before achieving a reasonable result.

 Watch a short video that shows you how the internal control points are positioned in Body Plan view while using the control box to switch columns. This video also shows how to use different view windows to track down any irregularities in the control point net. [Web | Disk]

Smooth Internal Control Points

After fixing the corner control points and shaping the edges, it is now time to look at the internal control points.

Ø  Show the control point net

Usually after you have not shown the internal control points for a while and made all sorts of changes to the edges and corner control points, the internal control point net can be quite messy. In this case it is actually not too bad as can be seen in the image above. There is a command available in Maxsurf that cleans up messy internal control point net by distributing the internal rows and columns evenly between the edge rows and columns in 3D. This usually provides a good starting point for further refinement.

Ø  Use the Smooth Interior Controls command from the Markers menu

Ø  Save the design as MyFirstDesign.msd

Body Plan

There are a couple of things you have to learn before we can model the internal surface in Body plan view.

 Lesson 1: From this moment onwards you should no longer modify the corner or edge control points; you have already shaped these points in the previous stages. Note that all of the points in the aft most and forward most columns are either edge or corner control points so do not touch those!

Lesson 2: Because the edge control points are fixed, the internal control points a, b and c can – in general – only be located in the green area unless you want a “tunnel bottom” (area 2) or tumblehome (area 1). Having said that, as you get more experienced you will see that areas 1 and 2 sometimes have to be used to create specific shapes, but for now it is recommended to only use the green area in the middle.

Internal control points should never be positioned in areas 3 and 4.

Lesson 3: Moving internal control points does not influence the shape of the edge of the surface.

Tips:

o         In general: Always try to minimise the amount of data (Contour lines, Markers, Control points etc.) displayed on your screen.

o         When you are working in body plan view it is easiest to work at one column at a time. It is important however to realise that the 3D shape of the vessel results from all columns and rows being fair in 3D. This means that even though a section might look fair in 2D Body Plan view, this does not necessarily mean it is fair in 3D. When working in a 2D window, always try to think about the 3D shape surrounding the area of the 2D section you are working on.

o         In a 2D window the movement of a control point is strictly restricted to movement in the plane of the window. For example: in Body Plan you can only move control points in the Y-Z plane and movements in the X direction (Fwd or Aft) is not possible. Movements in the X direction should instead be done in either the Plan or Profile view. Moving control points in Perspective view is also possible, but a little more complicated and will be discussed further on in the training manual.

Ø  Hide the Net

Ø  Switching between the columns using the control box, position the control points of each column to shape the internal surface.

There is no particular order you should do this in, but in this tutorial

Ø  Start with the 2^nd column from aft and work your way towards the bow

Ø  You can use your own creativity for the position of the internal control points, or use the suggested locations in the table below:

Ø   

Ø  Switch to Plan view to check your adjustments

Plan view or Profile view

After you have roughly positioned the control points in Body Plan view, check the position of the control points in Plan and Profile view.

Show the Net

Before you made changes in Body Plan it looked like this:

It may now look more like this:

Boats usually don’t get built with zigzags in the hullshape, so try to avoid these zigzags in the control point net as well:

Instead of zigzags, try looking for “bananas”: smooth curves.

Do the same in Profile view

Continue to make adjustments where necessary. Your aim should be to make all control points rows and columns “flow” in smooth lines, remembering that a smooth control point net results in a smooth surface.

Shaping the internal surface is a highly iterative process. Switching between columns in Body Plan view and switching to the other view windows often, will slowly make the design fairer. This fairing takes some experience and will be discussed later in the training material.

Perspective view

By rotating the model whilst showing the Net, all irregularities in the control point net become visible.

Making adjustments to the control points net in Perspective view is not recommended for inexperienced users.

The perspective window can also be used to find and select a control point that is difficult to select in one of the 2D view windows because it is hidden by other control points. In Perspective view you can rotate the model and find and select the control point you need. A selected control point in any view window in Maxsurf will also be selected in the other windows. For example:

In case you want to select this control point in Profile view..

But in Perspective view it is easy to find it and select it …

And in Profile view the control point is selected as well.

Ø  Show the Net

Ø  Check the control point net in the Perspective window by rotating the model

A minor zigzag can be seen in perspective view at particular orientation angles. Generally you will want to investigate this and fix it in the 2D view windows. You will learn more about this in the basic fairing section of this training manual.

Don’t spend too much time on the internal control points at this stage. When you are done with the model you can lock the surface from Surfaces | Locking:

Ø  Go Surfaces | Locking and place a tick next to the Hull surface.

You can also use Right click on the surface in the Assembly Pane, or use the Surface Properties dialog to lock the surface. Locking the surface will lock and hide all control points, preventing any unintended changes.

Ø  Save your design as MyFirstDesign.msd

Congratulations! You have created your first design by starting a new design and inserting and modifying a surface from the Maxsurf surface library. The next section in this training manual will take you through an alternative option to starting a design: Modifying an Existing Design.