So! The visual ray method takes point of view very seriously and it works like this:
- In Measuring Point Method (MP), you put elevations below the baseline and take the lines toward specified measuring points.
- In Visual Ray Method, you put elevations above the horizon and take the lines toward the Point of View of the Viewer (POV).
- This method works really well if you want to draw objects that are not parallel to one another. It also makes a lot of sense seeing a top-down view of how the viewer is looking at the scene.
- You start by setting your horizon line and drawing your elevation view above it.
- Place the POV (or Station Point) far back enough so that the natural human 60 degree field of view contains the entire scene in elevation.
- For each square to be drawn, draw parallel lines from the POV to the horizon line. Where these lines intersect are the vanishing points. Many objects can have their own vanishing points using this method.
- All of the lines on the elevation view show true lengths. So, provided the shape is a cube, you can find the height of the front edge by measuring any side of the 2D square.
- You can find the sides of the object by following the outside corners of the elevation view down to the POV. Where they intersect the horizon line, draw a vertical line straight down.
Here’s another measuring method to find the height of the sides of the square:
- find the length of the front edge, then take the sides back to the vanishing points.
- choose an arbitrary width to one side of the square.
- a line running parallel to the horizon will take this placement to the opposite side of the cube on a 45 degree angle of view.
- using a compass, where the centre is placed on one bottom corner of the cube and the pen is placed on the other bottom corner, draw an arc through the cube.
- draw a line 45 degrees up from the bottom corner where the compass centre was placed (you can use a piece of diagonally folded paper to measure this angle quickly).
- where the angled line intersects the arc is the height of the sides of the cube. a line running through this point, parallel to the horizon will show you this.
As well as top and bottom elevations, you can also use side elevations to find horizontal measurements, without the need for measuring points. As long as the elevation is lined up with the front edge, you can transfer the measurements from one to the other simply.
This is an elaboration of the grid system. To work out where the floor should be in relation to the horizon. It works well for 1-point perspective. Have not tried it for 2-point perspective.