# Modeling a detail of Centre Pompidou (NURBS)

In this tutorial you will learn how to create a detailed part of the construction of the Centre Pompidou in Paris, France.

If you are unfamiliar with Rhino start with a Rhino Introduction and probably other basic tutorials.

## Introduction

In this tutorial you will detail a main joint at the facade of the building. However this joint is a deviation of the standard joint. This is a joint with a extra rod for holding the stairs and galleries at the exterior of the building.

Before modelling in Rhino it is always wise to start with a plan. Analyze the detail and find out what primitive shapes like box, sphere, cylinder, etc. you recognize. Make notes of main measurements and how you will model and/or which commands you will use to create the details in Rhino.

## Basic shapes

Because of the large scale of this detail it is better to change your model units in centimeters before modelling.

Tools » Options... » Units

`Command: Units`

Start modelling with primitives from your analyzed sketches.

• Place a sphere with a diameter of about 60 cm in the center (0,0,0) of your co-ordinate system.

Solid » Sphere

• Place under and above the sphere vertical cylinders without the caps about quarter size of the sphere.

Solid » Cylinder

• Place in front of the sphere a disk with the same diameter as the sphere

Solid » Cylinder

This disk will be used to position a CPlane (Construction Plane). CPlanes come in very handy to place and create objects easier. Place the Cplane on the center of the disk.

Unfortunately there is nothing in the center, so you have to create a plane to orient the CPlane. Explode the disk and copy one of the round planes to the center.

• Use this highlighted plane to place the CPlane.

View » Set CPlane » To Object

• Place at both sides of the disk cylinders about half size of the sphere. Place the first cylinder about 70-80 cm from the disk and mirror with copy at the Z-axis of the CPlane. Use 0 (shortcut for co-ordinate 0,0,0) as the first point for mirror plane.
• Place at four sides of the disk cylinders thinner than the thickness of the disk (diameter approx. 5 cm). Place the first cylinder on a quadrant of the disk, move it about 5 cm from the edge and rotate it 45 degrees. Use again 0 as your center of your rotation point and enter <45 as your second reference point. This way the cylinder will snap every 45 degrees.
• Create with a polar array the other cylinders. Total number of items is 4.

Transform » Array » Polar

## Detailing basic shapes

• Divide the sphere in three parts (1/4 + 1/2 + 1/4) with two rectangular planes.

Surface » Plane

• Trim the upper and lower part of the sphere

Edit » Trim

• Trim in the flattened sphere also holes for the vertical cylinders. If needed, move the vertical cylinders so they connect to the flattened sphere.

The connections of the four rods to the disk are a bit thicker. Use the end of the cylinder to create a curve.

• Create a curve from the edge of the cylinder

Curve » Curve From Objects » Duplicate Edge

• Scale the curve like factor 1.5-1.6

To project the curve on the side of the disk you need to change the CPlane, because projections only work perpendicular to the CPlane.

• Use the curve to orient the CPlane in the desired direction.

View » Set CPlane » To Object

• Project the curve on the side of the disk

Curve » Curve From Objects » Project

• Make sure that you have copied the curves to all four sides of the disk perpendicular to the rods.

Tip: Transform » Array » Polar is probably the easiest way to copy the curves to all four sides.

• Trim holes at the projected curves on the disk
• Create a planar surface between the smaller end of the rod by selecting the surface edge and the curve. Do this for all four sides.

Surface » Planar Curves

• Make a loft between the two curves to create the thickened end of the rod.

Surface » Loft

• Create a polygonal curve with six edges. Make it as almost wide as the disk.

Tip: Use a side view to position the polygonal curve right.

Curve » Polygon » Center, Radius

• Project the polygonal curve onto the side of the disk.

Tip: Use the same view to project onto the right direction.

Before you make a hexagonal loft between the disk you need a polygonal curve away from the disk. The distance is about 15 cm.

• Move the polygonal curve about 15 cm away from the disk.

Tip: During Move command enter only 15 as second point at the commandline to keep the distance constrained. Keep shift pressed during move to keep the movement constrained.

• Fit a circle in the polygonal curve.

Curve » Circle » 3 Point

Tip: Snap to the midpoints of the edges.

• Select the polygonal curve to create a planar surface.

Surface » Planar Curves

• Trim hexagonal holes at both sides of the disk.
• Also trim the hole in the just created planar surface. Notice that there are 6 separate pieces now.

• Make a hexagonal loft between the disk and the trimmed surface.
• Make a tapered loft between the trimmed surface and the rod.

• Mirror the just created lofts and the trimmed planar surface (6 pieces) to the other side of the disk.

To be continued...