SURFACE ppt

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Surface
View a topic

Four Point Surface

Sheets From Curves

Bounded Plane

Transition

Through Points and From Poles


From Point Cloud

Ribbon Builder

Midsurface

Patch Openings


1. Four Point Surface
Use the Four Point Surface command to create a surface by specifying four points.
This is useful for creating base surfaces that support the surface based Class-A workflow. You can easily
modify such a surface by increasing the degree and patch into a more complex surface with the desired
shape.
You must follow these point specifying conditions:

 No three selected points can be collinear.
 No two selected points can be the same or at the very same location in space.
 Four points must be specified to create the surface. If you specify three or fewer points an error
message is displayed.

Four Point Surface
Where do I find it?
Application
Modeling
Menu
Insert→Surface→Four Point Surface
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1.1. Create a surface using four points
1. Choose Insert→Surface→Four Point Surface to open the Surface by 4 Points dialog box.
2. Select the four surface corner points in the graphics window. You can specify the four points
using any of the following methods:
o Select an existing point in the graphics window.
o Select any arbitrary point in the graphics window.
o Define the coordinate location of a point using the Point Constructor dialog box.
o Select a base point and create a point offset from the base point.
Note
The Snap Point options are useful when you want to specify an existing point on a
particular curve or surface.

4. Four specified points
5. Specifying subsequent points displays a polygonal preview on the screen. You can modify any
points before finalizing the shape of the surface.
6. Change the location of the points as required.

7. Relocated specified points
8. Click OK or Apply to create the surface.

9. Four Point Surface feature
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1.2. Four Point Surface options
Specify Points

Specify Point 1 - 4
Lets you select the first, second, third, and fourth points for the four point surface.
Preview
Preview
Select this check box to see a preview of the resulting surface.
2. Sheets From Curves
This option lets you create bodies through selected curves.

Note
Many illustrations in this section use solid fill shading to represent wire frame parts. The fill often
hides portions of curves that would be visible in a wireframe model. The purpose is to represent the
concepts with clearly recognizable figures at the loss of some technical viewing accuracy.

Local Settings
When you choose Sheets From Curves, the following options appear:
Cycle By
Layer
Processes all selectable curves one layer at a time. To speed up the processing, you may wish
to turn this option ON. This causes the system to create bodies by processing all selectable
curves one layer at a time. All the curves defining a body must be on a single layer.
Note

Using the Cycle By Layer option can significantly increase processing performance.
This option also significantly reduces the use of virtual memory. If you receive the
message: Virtual Memory Exhausted, you may want to spread the wireframe geometry
over several layers. But be sure to place all defining curves for a body on a single layer.

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Warnings
Causes the system to stop processing and to display warning messages after generating
bodies, if there are any warnings. You are warned about nonclosed planar loops of curves,
and non planar boundaries. If you select OFF, you are not warned, and processing does not
stop.
Basic Procedure
To convert curves to sheets, you must:
1. Set the Cycle By Layer toggle switch as desired.
2. Set the Warnings toggle switch as desired.
3. Choose OK.
4. Choose the curves you wish to sheet using the Class Selection Tool.
5. Choose OK.
The message Creating Bodies appears during this stage of processing. The system then uses all selected
curves to generate bounded planes, cylinders, extruded bodies, and truncated cones.
Tips and Techniques
You can generate bodies using any planar curve. Sheets From Curves creates the following bodies:
 Bounded planes - by forming planar closed loops (using the ends of curves)
Note
Single planar loops must be periodic.
 Cylinders - by pairing circles and ellipses with coaxial centers.
 Cones - by pairing arcs with coaxial centers.
 Extruded bodies - by pairing conics and planar splines. They must be on parallel planes and one
must project onto the other (via a translation perpendicular to the planes of the curves).

You can create bodies on one plane using:
 Loops of objects - These form a bounded plane. For example, the adjoining lines on any face of a
simple rectangle.
You can create bodies between two parallel planes using:
 Coaxial arcs - For example, two circles with the same radius become a cylinder, and two circles
having different radii become a cone. In both cases, they share the same axis and are parallel.
 Identical splines, parabolas, ellipses, hyperbolas - These form an extruded body; for example, the
thickness of the sole of a shoe.
Note
Two coaxial conics do not always have to lie on parallel planes. An ellipse and arc on
nonparallel planes can match and form a body if they are both segments of the same
cylinder. These objects appear similar when viewed along their common axis. See the figure
below.
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
Sheets From Curves does not create spherical sections. Before using this option, you must create sheets at
all sections of spheres. This option also does not create typical ruled sheets.
2.1. Sheets From Curves Design Considerations
Sheets From Curves usually develops the sheets you desire. However, you will be successful if you
follow certain design requirements:
Guiding Lines
Use guiding lines in ambiguous situations - You must connect defining arcs/ellipses if there are more than
two, and they are coaxial and geometrically similar (that is, the same size in degrees but not necessarily in
arc length). Otherwise the processor cannot determine which object to connect. See the figure below.

You must use arcs (not ellipses) to generate cones. The system always generates truncated (nonpointed)
cones.
It is always safest to create guiding lines using arc endpoints. But you can connect any points on two
circles if the guiding lines do not touch. If they do touch, you must use arc endpoints. See the figure

below.
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"Soft Edge" Recognition - It is not necessary to create guiding lines to form a bounded plane if there are
only two identical coaxial arcs limiting the plane. See the figure below.

Guiding Line Rules
When in doubt - use a guiding line.
In the figure below, area A shows that two coaxial arcs of the same size do not require guiding lines. The
processor is able to match the partial arcs and the full arcs without additional help.
However, in area B you must indicate whether the circles should form cones or cylinders.
Area C requires you to match the 4 lower arcs with 4 upper arcs. Because there are more than 2 similar
coaxial arcs you must connect the arc endpoints of the matched arcs. That requires eight guiding lines.
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Bounded Plane Rules
Bounded plane object members must form a single unambiguous closed loop. A closed loop does not split
and has no "dangling" object. Therefore the loop is reliably chainable.

In the example shown in the figure below, the boundary members of both front faces do not chain because
the upper line segment extends outside of each boundary.
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Normally the solution is to create two segments. However, in this particular example, the following
requirement further prevents sheet generation.
Only two coplanar objects can share an endpoint. This option cannot reliably create a body if a boundary
member object shares a common endpoint with more than one other object on that plane.

In the figure below, even though you subdivide the dangling line, you still may not succeed in creating
bodies the front faces. This is because each face has more than 2 coplanar objects that meet at a vertex.
Notice that lines 1, 2, and 3, in the figure below, are all on the same plane. They also share a common
endpoint. No. 1 effectively becomes a dangling line and that face is not turned into a sheet.
Lines 1, 2, and 4 present the same problem in another plane.
You must manually create sheets for these faces.

Bounded planes must not contain more than two colinear line segments. You cannot create a sheet if three
or more sequential lines are colinear. In the figure below, the front slope is moved towards the center of
its front face. The processor cannot create a bounded plane for the top sheet using the three colinear lines.
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You can generate a trimmed bounded plane if the interior objects do not touch or cross the boundary.

Assemblies
Place multiple assembly components on separate layers. They often have curves that cross or touch. The
figure below shows the bottom component trimmed by the base of the top component. The base of the top
component is not turned into a sheet either.

Multiple components on a single layer can cause more than 2 curves on the same plane to share a
common endpoint. Therefore, the bodies might not be properly created, or created at all. See the figure
below.
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Invalid Sheets
Trimmed Cylinders - You cannot generate a trimmed cylinder. The interior curves are either ignored or
converted as usual.

Not all sheets are generated, such as unknown sheet types and sections of spheres. See the figure below.

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2.2. Error Messages and Warnings
The following is a list of errors and warning messages you might receive. The warning messages are only
received when the Warnings option is turned ON:
When all virtual memory is used, the following error message is displayed. If this message occurs, put
wireframe components on different layers and use Cycle By Layer.
Virtual Memory Exhausted
When the loop of curves is not closed, this warning is displayed. This usually occurs at the endpoints of
two neighboring boundary curves. Occasionally this warning is displayed for legitimate planar strings
which are not intended to form bounded planes.
Planar Loop Is Not Closed
All of the curves which could not be attached to any loop on the plane, and not identified by the warning
Planar Loop Is Not Closed, are displayed with the following warning message. This usually means that
the curves are parts of loops which are disconnected. Occasionally this warning is displayed for open
loops which form legitimate planar strings which are not intended to form bounded planes.
Planar Loop(s) Are Not Closed
The following warning message means there are gap(s) in the chain of curves.
Boundary Not Chainable
The following warning message means the curves of a bounded plane are not coplanar.
Boundary Not Planar
The following warning message means the curves of a peripheral loop or hole, loop in a bounded plane
intersect.
Boundary Intersects
The following error messages mean that a sheet body could not be created from the specified surface.
Unable to Create Sheet Body Unable to Create Planar Sheet Body
3. Bounded Plane
Use the Bounded Plane command to create a planar sheet body enclosed by a set of end-connected planar

curves. The curves must be coplanar and form a closed shape.
To create a bounded plane, you must establish its boundary, and if necessary, define any internal
boundaries (holes). You can define the boundaries by selecting individual curves, or you can use
Selection Intent, as shown in the following animation.
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Two different bounded planes created on the same surface, one with holes and one without
Selection Intent's Tangent Curves rule used to create a bounded plane without holes.
Selection Intent's Region Boundaries rule used to create a bounded plane with holes
Where do I find it?
Application
Modeling
Toolbar
Surface→Surface Drop-down→Bounded Plane
Menu
Insert→Surface→Bounded Plane
3.1. Create a bounded plane
1. Choose Insert→Surface→Bounded Plane.
The Bounded Plane dialog box opens, and in the Planar Section group, Select Curve is
active.
2. Specify the planar section by selecting an unbroken string of bounding curves or edges. They must
be coplanar and form a closed shape.

3. Preview of bounded plane after selecting a single string of face edges
4. (Optional) You can do the following:
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o If there are discontinuous holes within the area bounded by the selected curves or edges
that you do not want included in the bounded plane, select them as inner boundaries.

o Two holes specified by selecting them as inner boundaries
o Use Selection Intent rules to quickly select the closed shapes that define the bounded plane
you want.
5. Click OK or Apply to create the bounded plane.

3.2. Bounded Plane options
Planar Section

Select
Curve
Lets you select a closed string of end-to-end curves or solid edges to form the boundaries of
the bounded plane.
The bounding string can consist of single or multiple objects. Each object can be a curve, a
solid edge, or a solid face.
A hole in a bounded plane is defined as an internal boundary where the sheet is not created.
You can create the bounded plane with or without holes, either by individual selection or by
using Selection Intent rules.
4. Transition
Use the Transition command to create a Transition feature at the intersection of two or more sectional
curves.
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You can:
 Impose either a tangent or a curvature condition on the sections.
 Have a different number of elements for the sections.
If you do not use a surface to impose match conditions on a section, a tangent condition is imposed that is
normal to the plane of the input section.
The Transition feature is parametric and associative to any geometry used in its creation.

Three sections (numbered) form a Transition feature
Where do I find it?
Application
Modeling
Toolbar
Surface→Transition
Menu
Insert→Surface→Transition
4.1. Create a Transition feature
1. Choose Insert→Surface→Transition.
2. Select the section elements for the first section. To aid selection, you can set the filter on the
Selection bar to Curve, Edge or Sketch.
3. In the Continuity group, set the continuity to (G0) Position, (G1) Tangent, or (G2) Curvature
and click OK.
The section is added to the list in the sections window.
4. (Optional) Click Reverse Direction if you need to reverse the section direction.
5. Repeat this sequence for each section you want to add to define the Transition feature.
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6. Preview of Transition feature using two sections
7. As you add sections, a wireframe preview of the point mapping between each of the sections is
automatically displayed.

8. Preview of Transition feature using three sections
9. After you have added all the sections, you can :
o Dynamically edit, insert and delete any of the bridge curve coupling points using the
options in the Support Curves group.
o Dynamically edit the shape of the bridge curves using the options in the Shape Control
group.

o Preview the Transition feature before you create it.
10. In the Settings group, select the Create Surface check box to create the Transition feature as a
surface. If you do not select this check box, only bridge curves are created.
11. Click OK or Apply to create the Transition feature.
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12. Transition feature
4.2. Transition options
Sections

Select Curve
Lets you select the elements for each section. The section elements can consist of
splines, lines, arcs, conics, surface edges, sketches and so on.

Reverse
Direction
Lets you reverse the section direction so that bridge curves can be remapped.

Specify Origin
Curve
Lets you specify the origin curve in each set of section curves.

Add New Set
Lets you add a new set of section curves.
List
List window
Shows a list of all the sections that you specified, their continuity, and their flow
direction.
Select (or deselect) a surface to change the flow direction at the selected section.

Changing the continuity of one section changes the continuity of all sections.
Constrain Faces
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Select Face
Lets you select faces to specify the constrain surfaces.
Support Curves
Show All Points
on Section
Displays all the section points of the selection section set. You can then select one of
the section's points.
List window
Displays the coupling points of the selected section curve.

Add
Adds coupling points to the selected section curve.
This option lets you add new coupling points and bridge curves to a section.
You can click Add to insert a coupling point in the section in front of the
currently selected point. The coupling point is added to the coupling point list, and a
bridge curve is added between the selected section and another appropriate section
that is determined by the software.

Remove
Removes the selected coupling point from the section curve.
This option lets you delete a coupling point from a section and its associated bridge
curve from a section. The option becomes available when the selected coupling point
has a coupling point associated with the other end of the bridge curve.
When you delete a coupling point, it is removed from the coupling points list, and its
related bridging curve is also removed.

Move coupling
point to other
section
Lets you move the coupling point to another section curve.
This option becomes available if it is possible to move the selected coupling point to
another section.
When you click the icon, the coupling point is removed from the list and moved to
the appropriate section.
Location
Lets you specify the location of the coupling point.
The slider becomes active when the point is a coupling point. It shows the correct
positional value of that point on the section (0.0 to 1.00 relative to the section length).
You can drag the slider to move the coupling point on the section.
Shape Control
Bridge Curve
Displays a list of all the individual curves and bridge curves you want to edit. You
can select bridge curves individually or as a group.
When you select a section that has the bridge curves you want to edit, this list updates
automatically.
Type
Lets you specify the type of shape control method from the following options:
 Depth and Skew — Lets you change the depth and skew of the selected curve
or group of bridge curves in a fashion similar to that used by the Bridge
Curve command.
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When you select a curve or group of bridge curves from the Bridge Curve
list, the curve is highlighted in the graphics window. You can then either drag
the Depth and Skew sliders to shape them or enter the required values in the

data fields.
 Tangent Magnitude — Lets you change the tangent magnitude of the
selected curve or group of bridge curves.
When you select a curve or a group of bridge curves from the Bridge Curve
list, the curve is highlighted in the graphics window. You can then drag the
Start and End sliders to shape them, or enter the required values in the data
fields.
Depth
Available only when Type is set toDepth and Skew.
Changes the depth of the selected bridge curve. You can either drag the Depth slider
or enter the required values in the data field.
For an example, see Changing the depth value of the selected bridge curve.
Skew
Available only when Type is set toDepth and Skew.
Changes the skew angle of the selected curve or bridge curve . You can either drag
the Skew slider or enter values the required values in the data fields.
For an example, see Changing the skew angle of the selected bridge curve.
Start
Available only when Type is set to Tangent Magnitude.
You can drag the Start slider to shape the start of the curve or enter the required
values in the data field.
For an example, see Changing the start value of the selected curve.
End
Available only when Type is set to Tangent Magnitude.
You can drag the End slider to shape the end of the curve or enter the required values
in the data field.
For an example, see Changing the end value of the selected curve.
Continuity
Continuity
Lets you assign the type of mating condition for the sections. Select from the

following options:
 G0 (Position)
 G1 (Tangent)
 G2 (Curvature)
Note
A surface must be selected to use G2 (Curvature).
You cannot assign G1 (Position) or G2 (Tangent) continuity to the faces
comprising the bottom of a Transition feature.

Settings
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Create Surface
Create the Transition feature as a surface.
Note
Only bridge curves are created if this check box is not selected.

5. Through Points and From Poles
The Through Points and From Poles free form features options use the same interactive creation
techniques, so they are described together in this section.

Through Points - Lets you define a rectangular array of points through which the body will pass. The
body interpolates each specified point. Using this option, you have very good control over the body
in the sense that it always passes through the points that you specify.

From Poles - Lets you specify points as poles (vertices) of a control net which defines the shape of
the sheet. Using poles gives you much better control of the overall shape and character of the body.
Using this option also gives you a much better chance of avoiding unwanted undulations (reversals
of curvature) in the sheet.

The options on the Through Points and From Poles dialogs are the same.
Through Points and From Poles Dialog Options
Patch Type
Lets you create a body containing a single patch or multiple patches.
Closed
Along
Lets you select a method for closing a multiple patch sheet body.
Row
Degree
Lets you specify the row degree (1 to 24) for a multiple patch. For a single patch, the system
determines the row degree from the row with the highest number of points.
Column
Degree
Lets you specify the column degree for a multiple patch (up to one less than the number of
specified rows). For a single patch, the system sets this to one less than the number of
specified rows.
Points
From File
Lets you define the points by choosing a file that contains them.
5.1. Create a Through Points & From Poles surface
To create a body using Through Points or From Poles, you must:
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1. Choose a Patch Type.
2. For multiple patch, choose a Closed Along method for closing the sheet body.
3. For multiple patch, enter the degrees for rows and columns. You do not have to specify degrees
for single patch.
4. Specify rows of points or poles to be used to create the body, using either the Point Specification
Method dialog or by using specifying a file containing the point definitions.
Patch Type

Single creates a body consisting of only one patch.
Multiple creates a body consisting of a rectangular array of single patches.

Closing the Patch
Closed Along lets you choose a method for closing a multiple patch sheet body using the following
options:
Neither
The sheet body begins and ends with the specified points.
Rows
The first column of points/poles becomes the last.
Columns
The first row of points/poles becomes the last.
Both
Closes the body in both directions (rows and columns).
If you choose to close the body in both directions or you close the body in one direction and the other
direction the ends are planar, a solid body is created.

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Degrees for Single Patch Bodies
For a single patch body, the system determines both the row and column degrees for you, depending on
the points/poles and rows that you specify.
The Row Degree (U direction) comes from the row with the highest number of points.
The Column Degree (V direction) is equal to one less than the number of rows you specify.
Note
The minimum number of rows or points per row is two (minimum degree of one) and the maximum
number of rows or points per row is 25 (maximum degree of 24 + 1).
The sheet shown in the figure below has 4 rows of points, so its column degree (V degree) is equal to 3
(=4-1). The largest number of points in any row is 6, so the rows degree (U degree) is equal to 5 (=6-1).

Degrees for Multiple Patch Bodies
For a multiple patch body, you must specify degrees for the rows and columns.
The Row Degree can be any number from 1 to 24. The default is 3.
The Column Degree can be set to any number from one to one less than the number of rows you specified.
The default is 3.
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Note
The minimum number of rows or points per row is two (minimum degree of one) and the
maximum number of rows or points per row is 25 (maximum degree of 24).
For example in the figure below, the row degree can be set to any number from 1 to 4. The column degree
is equal to 3.

Points/Poles
Once you have specified the degree and set the Patch Type and Closed Along parameter values, you must
specify the points in one of the following ways:
 Choose OK, then specify the rows of points using the Ordered Point Constructor, or the rows of
poles using the Point Constructor.
 Choose Points From File and specify the name of the file containing the point definitions. It must
be a Rows of Points type file.
If you use the first method, when you have specified two or more rows of points (enough to satisfy the
degree), you are prompted with two options:
All Points Specified
Creates the body and returns you to the dialog.
Specify Another Row
Lets you specify another row of points for the body you are creating.
5.2. Tips and Techniques
When specifying creation points or poles, you should select them by row in approximately the same order.
Otherwise, you might get undesirable results. The figures below show different object selection orders

and the resulting bodies.
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6. From Point Cloud
From Point Cloud lets you create a sheet body that approximates a large "cloud" of data points,
typically produced by scanning or digitizing. While there are some restrictions, this function lets you
create a body from a large number of points with a minimum amount of interaction.
The resulting sheet body is much "smoother" than one created from the same points using the Through
Points method, but is not as close to the original points.
From Point Cloud Feature Dialog Options
Select Points
Lets you select points when this icon is active.
Points From
File
Lets you define the points by choosing a file that contains them.
U Degree V
Degree
Let you control the degree of the sheet body in both U and V directions. The default
degree of 3 can be changed to any value from 1 to 24. (The default of 3 is recommended.)
#U Patches
#V Patches
Let you specify the number of patches in each direction. The combination of degree and
patches in each direction controls the distance error between the input points and the
generated sheet body.
Coordinate
System
Consists of a vector approximately normal to the sheet body (corresponding to the Z axis
of the coordinate system), and two vectors that indicate the U and V directions of the sheet
body (corresponding to the X and Y axes of the coordinate system).

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Boundary
Lets you define the boundary of the sheet body that you are creating.
Reset
Lets you create another sheet body without leaving the dialog.
Confirm
Upon Apply
Opens the Confirm Upon Apply dialog after you choose Apply, letting you preview the
results, and accept, reject or analyze them. This option is common to Selection Steps
dialogs.
In general, there are few requirements for the points you can use to create a sheet body with this function.
There is no restriction on the number of points, other than available virtual memory. The degree and
number of patches in the resulting sheet body is controlled by you, and is not determined by the number
of specified points.
There is no requirement on the organization of the points that are input. They may or may not be
organized in "scan lines".
Part of the information you must supply is a temporary coordinate system. The intended sheet body must
not "fold under itself" when viewed along the Z axis of this coordinate system; that is, for any given point
in this view there must be only one, unambiguous place it can exist on the sheet body.
Basic From Point Cloud Procedure
Following is the general procedure to create a From Point Cloud body. Also, see the abbreviated "quick"
method procedure.
1. Select the points, or specify a file that defines the points.
2. Specify the U and V degree of the surface.
3. Specify the number of patches in the U and V directions.
4. Specify the local U-V coordinate system.
5. Specify the boundary around the desired points.
6. Choose OK or Apply to create the sheet body.
The "Quick" Method

If you do not intend to specify a particular coordinate system, and you do not need to specify a boundary
around the desired points, you can use this "quick" method:
1. Orient your view so that you are looking down on the shape of the desired sheet body.
2. Drag a selection rectangle to enclose the desired points.
3. Enter the desired values for the degrees and patches.
4. Choose OK or Apply to create the sheet body.
6.1. From Point Cloud Options
Select Points

This is a required step, and the first step in creating a From Point Cloud sheet body. Notice that, when the
dialog first appears, the Select Points icon is active.
There are two ways you can specify the points:
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 Select the points by clicking and dragging a rectangle or by selecting them individually.
Robust selection is available, so you can add or remove points from those selected. As soon as you
select points, a boundary is displayed that encloses all the selected points, and the U and V
directions are displayed by vector arrows. As you select and deselect points, the size of the
boundary changes.
 Choose Points From File, then specify one or more files containing the point definitions. Each
point file must be a Series of Points type file.
Note
If you use more than one point file, only the name of the last point file is stored in the
POINT_FILE object attribute.
#U Patches, #V Patches
These options let you specify the number of patches in each direction. The combination of degree and
patches in each direction controls the distance error between the input points and the generated sheet body.
The number of patches you should specify depends on the degree of the sheet body in the corresponding
direction, the shape of the data in that direction, and the tolerance you are trying to achieve. A general
rule of thumb is that you need one patch each time the slope varies as much as 90 degrees in the

corresponding direction. You can use fewer segments with higher degrees.
Coordinate System
The coordinate system that you choose consists of a vector approximately normal to the sheet body
(corresponding to the Z axis of the coordinate system), and two vectors that indicate the U and V
directions of the sheet body (corresponding to the X and Y axes of the coordinate system).
You have five options for defining the coordinate system:
View of
Selection
The U-V plane is in the plane of the view, and the normal vector is normal to the view.
The U vector points to the right, and the V vector points up.
WCS
The current Work Coordinate System.
Current View
The coordinate system of the current work view.
Specified
CSYS
Selects the coordinate system previously defined by using Specify New CSYS. If a CSYS
has not been defined, this will behave just like Specify New CSYS.
Specify New
CSYS
Brings up the CSYS Subfunction, which you can use to specify any coordinate system.
With the View of Selection method, if you rotate the view (or modify it in some other way) after selecting
points, this coordinate system may be different from the Current View coordinate system. (Or, if you
select from a view other than the work view in a multiview layout, the View of Selection coordinate
system is different from the Current View coordinate system.)
It is important to remember that the normal vector of this coordinate system does not need to be exact. It
simply must satisfy the requirement that, when the points are viewed down this vector, they not form a
sheet body that folds under itself. Many vectors can meet this requirement (see the figure below).