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Selecting edge loops
Lesson 1: Modeling a polygonal mesh
Editing components in the perspective view
Editing components in the orthographic views
Component
selection and transformation is one fundamental method for editing
the shape of a polygon mesh. As you model, you’ll find yourself
frequently examining and then refining the position of the polygon
components (vertices, edges, and faces) while working in the various
scene views so they match the reference images on the image planes.
To
manually reposition the vertices on the rear of the helmet
- Right-click
the helmet and select Vertex from
the marking menu that appears.
- In
the side view, select the pair of vertices at the rear lower edge
(see image) by dragging a bounding box around them.
- In
the Toolbox, click the Move
Tool.
- In
the side view, click-drag the blue arrow on the Move
Tool manipulator towards the right until the vertices
are repositioned so that your helmet matches the reference sketch
on the image plane.
By moving the vertex as well as the vertex adjacent
to it along the axis of symmetry, you ensure that the symmetrical
shape of the helmet is maintained. If you move one vertex independently
of the other it may result in an unwanted bump or valley in the
mesh. These types of anomalies will become more apparent when you
copy the completed half of the mesh across the axis of symmetry.
- Repeat
steps 2 through 4 for the other pairs of vertices on the rear of
the helmet. Ensure that the edge loops appear smooth in relation
to each other.
When you have finished, the back region of the
helmet should closely match the reference image on your image plane.
- In
the side view, select other pairs of vertices along the top and
front of the helmet and move them in a similar fashion so they match
the reference image. Do not reposition the vertices for the top
of the face shield yet.
TipYou can click in the center of the Move
Tool manipulator to drag a vertex selection freely.
Next, you’ll reposition the border edges that
lie along the bottom edge of the mesh. You can select these edge
types using the Select Border Edge Tool.
To
reposition the lower border edges on the helmet
- In
the side view, select the lowest horizontal edge loop on the helmet
by choosing
Select > Select Border Edge Toolfrom
the main menu, and then clicking the first and then the last edge
on the loop as indicated in the image below.
- Using the Move Tool,
drag the selected edge loop downwards until the left hand vertex
roughly matches the lower edge indicated in the reference sketch.
- In
the side view, select and reposition the remaining vertices individually on
the edge loop using the Move Tool so
they match the reference sketch.
NoteUp to this point in the lesson, you’ve been
instructed to reposition the vertices on the helmet mesh only within
the side view (Y, Z plane). Once you achieve the shape you want
in the side view you will then concentrate on how the model appears
when viewed from the front and perspective views.
To
edit the border edges on the upper edge of the face shield
- From
the Select menu, choose Select
Border Edge Tool.
- In
the side view, click the first border edge that will be used as
the upper edge of the face shield, then click the last border edge
(see image).
The border edges in between are selected.
- In
the Toolbox, select the Rotate
Tool by clicking its icon.
- In
the side view, click-drag the rotate manipulator in a clockwise
direction until the border edges are rotated at roughly the same
angle as the corresponding edge in the reference sketch.
- With
the border edges still selected, click the Move
Tool again and drag the green manipulator upwards to
match the location of the border edges in the reference sketch.
- Reposition
the pairs of vertices on the upper front of the helmet to match the
reference sketch.
At this point in the lesson, the outline of
your helmet should roughly match the helmet in the side view reference
image. If it doesn’t, review the earlier steps in this lesson and
make any adjustments to your polygonal mesh as required.
If you view your helmet in the front orthographic
view, you’ll notice that the helmet shows a wider profile from this
view than the reference sketch. In the next steps you’ll correct
this using the front and top orthographic views of the helmet for
reference.
To
reposition vertices on the side of the helmet to match the sketch
- Display
the front view.
- In
the front view, select the vertices that extend beyond the outline
of the helmet as shown in the reference sketch (see image).
- In
the front view, move these vertices to the left until they match
the widest area of the helmet in the reference sketch (see image).
When you view your helmet from the top orthographic
view the region between the side and rear of the helmet appears
a bit flat in relation to the other areas. To correct this you can
move the other vertices in this region outwards in a similar fashion
so the curvature in this area appears fuller and more rounded. However,
viewing only from the orthographic views can be limiting, and you
should also use the perspective view to examine the mesh.
To
examine the mesh using the perspective view
- Enlarge
the perspective view.
- Dolly
and tumble the perspective view while you closely examine the helmet
mesh.
As you examine the vertices along any particular
edge loop, the vertices on the mesh should appear to cascade in
a smooth gradual fashion to create the curvature of the mesh with
no undesirable spikes or dips.
Ensuring that the mesh appears relatively smooth
at various stages throughout the modeling process will reduce the
possibility for issues when you create a high resolution version
of the mesh later on.
If you find areas where one vertex (or more)
appears to protrude outwards (or recedes) on the mesh in relation
to neighboring vertices, you can correct these protruding regions
by repositioning the affected vertices in the perspective view.