All vertical lines remain vertical unless you are a very high or low view point. Perspective sketches are in photographic proportion and easier for most clients to visualize. All vertical lines remain vertical in both isometric and perspective sketches unless a very high or low viewing angle is selected. Shading adds realism and three-dimensionality to sketches if it faithfully renders lighting effects. Shading is on the object and shadows are cast on the ground near the object.
Highlights indicate the direction of the light source.
All drafting is done on standard sizes. A size sheet. It is 8.5x 11 inches. A size sheet is 9x12 inches. Inked or computer plotted drawings use different pen widths while inking or plotting to achieve similar effects.