Eneroth Scaled Perspective
Tells what height current view should be displayed at to be to a given scale in a given plane.
Eneroth Scaled Perspective

This plugin is used to make perspective views scaled on a given plane, e.g. at a section cut.

The tool is activated from Extensions > Eneroth Scaled Perspective. Enter desired scale in the dialog window. The scale can be written without units such as 1:100 or with such as 1/16":43,7m.

Click in the model to select the plane scale should apply to. This plane is always perpendicular to the camera direction. To use the plane of a face or section plane, first right click it and select Align View.

The view can either be saved as a scene and referenced in Layout or exported as 2D graphic. When creating the drawing layout, set the height of the viewport/image to the the value shown in the dialog for the scale to apply. In Layout you can then enable 'Preserve Scale on Resize' under 'Sketchup Model' To change the extents of the viewport without altering the scale further.

The plugin can also be use to scale parallel views but the native scale field in layout is better suited for this. When scaling parallel view using the plugin the plane is irrelevant since the scale is the same at all depths in the view.

A new feature in version 1.1.0 is the ability to set the perspective viewing distance. This can be used to greatly improves consistency between scaled perspectives that are shown side by side. As a kid I typically constructed my perspectives with a 20cm viewing distance but I haven't been able to find much information about what is recommended. To reset the camera after using this feature, activate the zoom tool (Z), type in 30 or 35 and hit enter.

For consistency between different scaled perspectives it's also important to have the camera on the same height. To precisely set the camera height, active Look Around tool (the eye), type in a height over the model origin and press enter.