Transform - Clip with (Intersect) / (Subtract)

The Clip with operators in the Transform toolbar for drawings use one or more areas to "clip" other objects, leaving only those parts of the other objects that lie within the areas (Intersect) or removing those parts of the other objects that lie inside the areas (Subtract).

For clarity, the following examples show use of only one clipping area. However, more than one area may be in the "clip with" set. The examples use one area to clip lines. The commands also work when areas are used to clip other areas, no matter how topologically complex the areas involved may be.

Clip with (Intersect)

$images\sc_transform_clipwithint01.gif$

Using a drawing that shows the state of Texas overlaid with lines forming a grid, we first select the state of Texas and save it within the View - Selections dialog as a saved selection called Texas. We can select the lines and then apply the Clip with (Intersect) command in the Transform toolbar:

$images\tbar_transform_clipwithint.gif$

The Transform toolbar knows we have made a selection, so the target box is loaded with the selection as the target. We choose Texas in the source / argument box (all of our saved selections will appear as possible choices in the source / argument box) and press Apply.

$images\sc_transform_clipwithint02.gif$

The result is to split all objects at their point of intersection with the periphery of the Texas area and to discard all objects lying outside of Texas. This is called an "intersection" because it retains all objects where there is an object and there is Texas.

$images\sc_intersect_01.gif$

Suppose we have two drawings in a map. Drawing B contains green rectangles and Drawing A contains blue circles (seen with 50% opacity above the rectangles layer).

$images\sc_intersect_02.gif$

If we use [All Objects in Drawing B] Clip with [Intersect] [All Objects in Drawing A] in the transform toolbar the result is seen above. Drawing A has been turned off. What is left of the rectangles is the intersection between objects in Drawings A and B. Note that this intersection operation removed everything from the rectangles except the region of intersection. If we wanted to retain the original rectangles as well as the intersections we could have made a copy of Drawing B and used that in the Clip with [Intersect] operation.

Clip with (Subtract)

$images\sc_transform_clipwithsub01.gif$

Beginning once again with Texas overlaid with a grid of lines, we can apply the Clip with (Subtract) command.

$images\tbar_transform_clipwithsub.gif$

The toolbar is the same, except we choose Clip with (Subtract) and hit Apply.

$images\sc_transform_clipwithsub02.gif$

The result is to split all objects at the boundary of Texas and to subtract all objects that lie within Texas.

Clip with Works with All Objects

These commands also work when areas are used to clip other areas, no matter how topologically complex the areas involved may be.

$images\sc_transform_clipwith01.gif$ $images\sc_transform_clipwith02.gif$ $images\sc_transform_clipwith03.gif$

The illustrations above show Clip with (Intersect) and then Clip with (Subtract) applied to two areas using Texas as the "clip with" area.

It is often the case that we have a map showing roads, lakes and other objects throughout an entire region and we wish to make a map that shows only the objects within a part of the region, such as a specific state or province. The Clip with commands are a straightforward means of cutting out only those objects within the desired state or province. Simply use the state or province as an area object with Clip with (Intersect) to cut out only those parts of the objects that are within the desired area.

To keep the illustrations in this topic simple, only illustrations using either lines or areas have been used; however, the commands work perfectly no matter what mix of objects is in the target set.