Argos User Manual
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Zoom Mode

Zooming is one way to get a better look at a portion of the data in a viewport. There are two types of zooming: geometric zooming and logical zooming. Geometric zooming produces a blown up version of the region in which each pixel in the source image is represented by a small square of the same color. Logical zooming produces a plot based on the actual observations in a source region. As a result, more details can be revealed. Let's take a look at some examples. Suppose Figure 9-4 is a viewport and you would like to zoom into the area bounded by the blue rectangle.

Figure 9-4. Source Viewport

---> images/zoom-source.png <---

Panel A of Figure 9-5 is the result of geometric zooming. Panel B of Figure 9-5 is the result of logical zooming.

Figure 9-5. Geometric zooming vs. logical zooming

Panel A: Geometric zooming. Panel B: Logical zooming.

Note

---> images/zoom-geometric.png <---
---> images/zoom-logical.png <---

Argos's zoom mode carries out logical zooming.

A zoom lens has 2 components: objective and ocular. To zoom into an area, conceptually, you first aim the objective of a zoom lens at the target area and then the corresponding ocular of the zoom lens will pop up. In physical terms, to carry out a logical zooming operation, move the mode cursor to the place that will be one corner or one side of the target area, depending on whether this viewport is based on 2 or 1 variable, press the left mouse button, and drag the target area into shape.

Note

You can abort a zoom operation by clicking the right mouse button.

The ocular is also a viewport. When the target area of an objective is moved to a new place, the associated ocular will update its contents accordingly. The rectangle that delineates the target area of an objective is the rim of the objective. The tic box in an ocular is constrained to be of the same color as the rim color of its objective. The tic box in a viewport that isn't an ocular is always black. An ocular inherits all the modes supported by the viewport at which its objective aims, which means you may carry out further logical zooming on the ocular. When a viewport is zapped, all the oculars that originates from it will be zapped. If a zapped viewport is also an ocular, the associated target area will be erased from the viewport at which the corresponding objective aims.

Let's see some examples. Figure 9-6 is a viewport aimed at by 2 zoom lenses.

Figure 9-6. A viewport aimed at by two zoom lenses

---> images/source-with-two-lenses.png <---

One zoom lens has a red objective rim and its ocular is Panel A of Figure 9-7; the other zoom lens has a green objective rim and its ocular is Panel B of Figure 9-7.

Figure 9-7. Oculars

Panel A: Ocular with a red objective rim. Panel B: Ocular with a green objective rim.

Note

---> images/ocular-red.png <---
---> images/ocular-green.png <---

If you zap the ocular in Panel B of Figure 9-7, the green objective rim in Figure 9-6 will be erased and Figure 9-6 will look like Figure 9-8.

Figure 9-8. The viewport after the ocular with green objective rim was zapped

---> images/source-with-one-lens.png <---

All oculars are registered under their target viewports in the scenegraph. For example, the following scenegraph snapshot

---> images/scenegraph-of-four-oculars.png <---

tells you that there are 2 zoom lenses aimed at "Scatterplot 1", "Ocular 3" is zoomed into to produce "Ocular 4", which is zoomed into again to produce "Ocular 5".

In addition to left mouse button operation to carry out a logical zooming operation,

Supporting Functions

Set Objective Rim Color...

Selecting this menu entry will generate the following menu:

---> images/color-palette.png <---

You change the color of an objective rim so that you can tell which objective is associated with which ocular.

Move Objective Target Area...

Selecting this menu entry will turn the cursor into and objective rims in the viewport will be redraw with dashes (e.g., Figure 9-9). Press the left mouse button inside of an objective rim and drag it to a new location.

Figure 9-9. Moving objective target area

---> images/move-objectives.png <---

Note

You can abort by clicking the right mouse button while dragging an objective rim. If you click the left mouse button outside of any objective rim, this operation is aborted, too.

Size Objective Target Area...

You invoke this to change the magnification factor. Selecting this menu entry will turn the cursor into and little cue boxes will be drawn at each corner of an objective rim, if the objective rim is big enough (e.g., Figure 9-10). Press the left mouse button inside of an objective rim and drag the objective rim into the size you want. You don't have to press inside of the little cue boxes; they just serve as visual feedback.

Figure 9-10. Reshaping objective target area

---> images/size-objectives.png <---

Note

You can abort by clicking the right mouse button while dragging to specify a rectangle. If you click the left mouse button outside of any objective rim, this operation is aborted, too.

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