4. Using the PDT lens
4.1 Lens basics
A PDT lens has three distinct parts: the focal region, the shoulder, and the base. The focal region is
the central region within the lens displaying a single, uniform magnification. The shoulder is the area
between the focal region and the base where the magnification varies smoothly between the focal region
scale and the base scale. The base is the outer edge or perimeter of the lens.
The PDT lens.
The lens controls consist of several components on and around the lens:
the boarders or thin frames, the magnification slider,
the scoop slider and the selection handles on and around the
lens. These controls are used for configuring the lens in real time.
Find out more:
4.1.1 Activating the interactive PDT lens controls
If the PDT lens controls are not active, choose the Activate lens button (i.e.
the arrow) from the toolbar.
Activate Lens
4.2 Using the interactive lens controls
Now you are ready to begin using the PDT lens to display detailed
areas of your image in context of the entire base image. This section describes the
basics of using the lens controls to manipulate the lens. Each lens control is
indicated by a cursor change as it moves over the control.
Cursor changes on the lens controls (cursors enlarged for clarity).
When a PDT lens is added to the image, the lens is active, making
the lens controls visible. The lens controls on an active lens allow you
to change the focal region magnification, lens size, and lens placement
on the image.
The PDT lens is considered inactive when the lens is visible but
the lens controls are not shown. This occurs when one of the interaction
modes apart from Activate lens are chosen (e.g. Draw curve
or Draw line).
It is useful to make the lens inactive
if the lens controls are obscuring the region of interest on the image.
An active lens (left), and the same lens inactive (right).
Find out more:
4.2.1 Exploring with the lens
You can explore the data or pinpoint a specific area on the image by changing the
lens position in one of two ways: Moving the lens, or Placing the lens.
4.2.1.1 Moving the lens
The Move lens function allows you to click and drag on the PDT lens and
move it to a new location. While the lens is in motion, the handles disappear,
allowing you to clearly see the detail in the lens in context to the entire base image.
The PDT lens controls: moving the lens.
To move the lens to a new location
-
Move the cursor over the PDT lens until it changes to crossed double arrows. Avoid clicking on the frames or selection handles.
-
Click on the lens and drag it to the new location.
See also Placing the lens.
4.2.1.2 Placing the lens
The Place Lens function allows you to select the PDT lens and move
it to a new location while still being able to see the previous
lens location. The main purpose of this function is to allow you to
select a very specific new location for the
lens within the current shoulder, or elsewhere on the image.
The PDT lens controls: placing the lens.
To move the lens to a precise location on your image
-
Move the cursor over the edge of the lens frame until it changes to crosshairs.
-
Click on the lens edge and drag the lens outline until the center box is over the desired location.
-
Releasing the mouse will instantly move the lens to the selected location.
Note: the center box of the outline indicates the area that will be contained within the focal
region once the mouse is released.
See also Moving the lens.
4.2.2 Resizing the lens base
Resizing the PDT lens base allows you to control both the size of the
lens relative to the image, and the width of the lens shoulder.
The focal region
is constrained by the lens base, so if you wish the focal region to be
larger than the current lens base, you will first need to enlarge the base.
The PDT lens controls: resizing the base.
To change the size of the lens base
-
If the lens controls are not visible, click on the
Activate Lens button.
-
Move the cursor over the selection handles on the corners of the frame around the lens base until the cursor changes to a double arrow.
-
Click on the selection handle, and drag to increase or decrease the size of the base.
Note: the lens base cannot be made smaller than the focal region. See Resizing the focal region. If you wish to view a smaller lens base, the focal
region must be decreased first.
4.2.3 Resizing the focal region
Resizing the focal region of the PDT lens allows you to increase or decrease the area that is
uniformly magnified by the lens. You can also resize the focal region to change the width of the lens shoulder.
The PDT lens controls: resizing the focal region.
To change the size of the lens focal region
-
If the lens controls are not visible, click on the "Activate lens" button.
-
Move the cursor over the selection handles on the corners of the frame around the lens focal region until the cursor changes to a double arrow.
-
Click on the selection handle, and drag to increase or decrease the size of the focal region.
Note: the focal region cannot be made larger than the lens base. See Resizing the lens base
4.2.4 Folding the lens
Folding the lens allows you to inspect areas of interest in the shoulder of
the lens without moving the lens. If you cannot clearly see data in the lens shoulder,
fold the lens to extend the shoulder region to make the data easier to view.
The PDT lens controls: folding the lens.
To fold the lens
-
If the lens controls are not visible, click on the
Active Lens button.
-
Move the cursor over the outline of the focal region until the cursor changes
to the folding cursor (two boxes with an arrow between them).
-
Click on the outline of the focal region and drag to move the focal region to
a new location, thus increasing or decreasing the visible size of the shoulder.
4.2.5 Changing the lens magnification
Adjusting the magnification changes the level of detail displayed in the
focal region of the PDT lens. The
magnification within the focal region can be adjusted between 1x and 7x the scale of
the visible image.
The PDT lens controls: changing the magnification.
To change the magnification within the lens
-
If the lens controls are not visible, click on the "Activate lens" button.
-
Move the cursor over the magnification slider until the cursor changes to the half arrow with +/-.
-
Click on the handle of the magnification slider and drag it up or down to adjust the magnification.
- or -
Click within the magnification slider, and the lens magnification will jump to the selected level.
4.2.6 Changing the lens scoop
The scoop of a PDT lens is a description of the steepness of the
upper part of the lens shoulder near the focal region. The greater the
scoop of the lens, the steeper the upper shoulder.
Increasing lens scoop makes detail
in the lower shoulder more visible. Decreasing lens scoop makes detail
in the upper lens shoulder more visible.
Adjusting the lens scoop is advantageous in cases where the magnification factor
of the lens, or the size of the focal region, are great enough to cause
detail on the lens shoulder to be hidden from view (i.e. occluded). If you
notice occlusion in the lens shoulder, adjust lens scoop.
The PDT lens controls: changing the scoop
To change the scoop of the lens
-
If the lens controls are not visible, click on the "Activate lens" button.
-
Move the cursor over the scoop slider until the cursor changes to the half arrow with
the wave.
-
Click on the handle of the scoop slider and drag it left or right to adjust the scoop.
- or -
Click within the scoop slider, and the lens scoop will jump to the selected level.
(C)Copyright 2002 IDELIX Software Inc.