Scaling the Plane

This task introduces the Scale Planes command which lets you measure objects directly on screen with a 1:1 scale (i.e. real size display) or with a lower/greater scale according to your needs.

Note that:

you cannot use this command when working with a multi-view configuration
you cannot use this command in 2D viewers. It works in 3D viewers only.

For an optimized accuracy, you need to store your screen dimensions (in millimeters), in the following two variables:

set CATWidthMMOfScreen = width_in_millimeters (on Windows)
or
export CATWidthMMOfScreen = width_in_millimeters (on UNIX)
set CATHeightMMOfScreen = height_in_millimeters (on Windows)
or
export CATHeightMMOfScreen = height_in_millimeters (on UNIX)

Otherwise, the measured dimensions may vary depending on the operating system.

You have to do these measurements by yourself using a tape measure. The screen dimensions correspond to the horizontal measurement followed by the vertical measurement.
If your computer does not use the full screen for display (e.g. if there is a strip on the left side and right side of your screen), you have to measure only the part of the screen used for display.

Open the ScalePlanes.CATProduct document.

Select View > Render Style > Perspective or View > Render Style > Parallel to display the object in a perspective or parallel view, respectively.

In our example, the object is displayed in Parallel view:

Perspective is related to the size of the object being viewed and the distance from the object to the observer.

In the power input box, key in the following command:

`c:Scale Planes` then press `Enter`.
	This command is also accessible via the `Commands` tab of the `Customize` dialog box. For more information on customizing commands, refer to Customizing Command Properties in this guide.
The `Scale Plane Properties` dialog box opens:

Click Apply to display the plane and keep the Scale Plane Properties dialog box:

As shown in the picture, the plane is represented by a transparent grid which lets you visualize the object displayed behind.

This grid is divided into squares and the space between these squares as well as the width and height (in millimeters) correspond to the values displayed in the Scale Plane Properties dialog box.

In our example, the width is 200 mm and the height is 100 mm. In the picture above, you can see that:

the width is divided into 20 squares, each of them being equal to 10 mm (as indicated in the Vertical spacing box)
the height is divided into 10 squares of 10 mm each (as indicated in the Horizontal spacing box).

If you set the space between vertical and horizontal lines to "20 mm", the grid looks like this:

The width is now divided into 10 squares of 20 mm each and the height into 5 squares of 20 mm each.

In the Scale Plane Properties dialog box, key in a Scale value.

The default value ("1") provides a real size display whereas "0.5" corresponds to a halfsize display. You can thus measure small objects by entering a scale factor greater than 1 as well as big objects by entering a scale factor lower than 1.

Set the plane Width and Height in millimeters. In our example, we keep the default values.

Set the space between vertical and horizontal by entering a value (in millimeters) in the Vertical spacing and Horizontal spacing boxes, respectively.

In our example, we keep the default values.

If the value you enter is not a multiple of the value set for Width or Height, the space between squares are approximated to give a round number (and this may make it more difficult to measure directly on screen).

The Show the grid check box lets you activate or deactivate the grid display.
It is recommended to display the grid when you are working in a conical projection.

Click OK (or Apply then OK) to validate and close the dialog box.

Adjust the viewpoint so that the object is correctly snapped on the grid. To do so, follow the instructions below according to the view you selected:

if you are working in a parallel view (i.e. cylindrical projection), running the `Scale Planes` command moves the user viewpoint so that the object is automatically displayed in the selected scale. You just have to translate the viewpoint horizontally or vertically to align the object on the grid:

	The zoom mode is locked when the `Scale Planes` command is running. By "locked", we mean that zooming has an impact on the grid position only and not on the display scale in order to let you translate the grid on the model along its depth and measure the model. Note also that if the grid is far from the model, then the grid disappears because measuring a dimension without the model does not make sense.
if you are working in a perspective view (i.e. conical projection), zoom progressively until the object is displayed in front of the grid then translate the object as necessary to align it with the grid and facilitate the measurement:

Let`s have a look at our model which has been correctly positioned. We are now able to measure the hole diameter and we see that the size is comprised between 60 and 100 mm: `100 mm - 60 mm = 40 mm` We can also count the number of squares: `4 squares of 10mm each = 4 x 10 = 40 mm` according to the values defined in steps 3 to 5.

	Translating or zooming the object does not affect the grid size since its dimensions are defined in the `Scale Plane Properties` dialog box.

To exit the command, click Close in the Scale Plane Properties dialog box.

You can also key in c:Scale Planes once again in the power input box.