Perspective: Building a Grid - Part One; 1PP

Started discussing using grids to make proportional perspective drawings in class today. Here is the first of several parts on the subject. This first one being a 'getting started/basics review' thingy. WARNING: The following are very crude note sketches that blew out in contrast when scanned, please forgive the crudity of the drawings herein.

1) As always begin with your horizon line (HL), intersect with the central vertical axis (CVA), and plot your station point (SP)
2) Measure the height from SP to center of vision. In this case I'm thinking the camera or viewer is at 6 feet. Then bring the distance down.

Before we forget it, find the median point (MP). For more info on that go here.
Bring convergence lines down to the measurements on the base line as shown in blue. To start laying in the horizon lines to complete the grid, first we need to find a perfect square and we use the MP to do this. Remember, we need a perfect square otherwise the measurements will be off so refer again to the Perspective basics handout linked above.Now that you have found a square in distance, you can easily plot more grid lines as they move back toward the center of vision.
To do this, let's take a moment to discuss how to draw repeating objects in space. Above I have included a certain sized plane receding in space.
Find the center of the plane by connecting the opposing corners with lines as shown.
Draw a convergence line which passes through the direct center of the plane to the vanishing point (Step 1). Next draw a line from either of the nearest corners of the plane so that it passes the half division of the farthest side of the plane and continues to the opposite convergence line as shown in Step 2. Step 3, drop a line perpendicular to the horizon to the other convergence line.
Repeat the process as shown above. You now have same sized planes positioned right next to each other which recede proportionally in space.
Back to the grid, just use this process to place lines parallel as they recede. Here I have added the 'center line' of the nearest square.
Repeat the above steps as shown.
Soon you'll have yourself a quality grid that is based on true square as determined by the MP. Here's an example of using a grid for a book I'm working on. (And you thought these are just random assignments to keep you from playing Call of Duty huh?) I will add more this soon. I will post more on this topic soon, stand by. For now I am going to wade through all the other stuff that is demanding my attention. Have fun drawing.