We are currently working on normal surfaces in my Engineering drawing class. The book that is assigned to the students has very minimal instructions on how to understand or do the material. I have a problem sketching orthographic views into a pictorial view. I don't any problem looking at a pictorial view or 3 dimensional of an image and then drawing the orthographic views like I did in Image1 but when I am given the opposite I am totally confused about how much the depth of the Image should be for example , Image 2. I would really appreciate it if someone can explain this.