How to Make a Cross Sectional Diagram

Cross-sectional diagrams show spatial relationships.

Cross-sectional diagrams illustrate spatial relationships between objects within a space -- for example, walls and furniture in buildings, parts of a plant stem, landscape elevation or organs in the human body. Cross-sectional diagrams are commonly used in architectural engineering, geology, geography and biology. Drawing cross-sectional diagrams requires measurement or estimation of spatial relationships among objects. You can learn the basic principles for drawing cross-sectional diagrams by creating a cross-sectional diagram of your bedroom. Apply these same principles to create additional cross-sectional diagrams based on relational measurements.

Things You'll Need

• Room with furniture
• Graph paper
• Pencil
• Eraser
• Ruler
• Measuring tape

Instructions

1. Select a cross-sectional plane in the room you will diagram; this plane is an imaginary line from one side of the room to the other side.

2. Measure the distance across the width (i.e., the floor) of the cross-sectional plane. Draw a horizontal line on graph paper to represent this width -- use a scale of 1/2 inch per foot (if your room is 10 feet wide, draw a 5-inch line).

3. Measure the height from the floor to the ceiling on each side of the room. Draw vertical lines on the graph paper to represent each wall. If your ceiling is not flat, measure the highest point of the ceiling and measure the distance from one wall to a point directly beneath the high point of the ceiling. Make a mark on the graph paper to represent the high point of the ceiling and draw a line from this point to the top of each wall.

4. Identify furniture objects that intersect the imaginary cross-sectional plane in your room. Examine each object closely to determine which parts of the object intersect the plane and must be drawn. For example, a cross-section diagram of the center of a dresser will appear as a legless box floating in the air, because the legs are out of the cross sectional plane and you will not draw them.

5. Measure the distance from the closest wall to the front and back of each object and from the floor to the top and bottom of each object. Make marks on your diagram corresponding to these measurements -- think of the floor and wall as the reference points and the measurements as X and Y coordinates. Draw lines to connect these points and sketch the outline of objects in the cross-sectional plane.

6. Measure or estimate the dimensions of internal details within each furniture object and draw them. For example, draw cross sections of drawers filled with socks, layers of bed covers and books and other items on shelves.

7. Measure or estimate the dimensions of as many additional objects in the cross-sectional plane as possible and draw them. For example, you might draw a cross section of picture frames on the wall, a ceiling fan or even your dog's ball on the floor.

Tips & Warnings

• Measure each distance twice to improve accuracy; measure the distance from both walls or from the floor and ceiling.

• Remember to keep your drawing to scale to ensure that you maintain the correct representation of the relative position of objects.

References

• The PUMAS Collection: Cross Section and Slope
• Pearson Publishing: Drawing a Cross Section
• Explorations in Earth Science: Making Cross Section Diagrams