[Figure 7] The sides of the box represent the views used in orthographic projection.

Image Planes
When starting with an image plane in a modeling program, consider the following process for setting up the plane. The images should be in a usable digital format and at a usable resolution. For most modeling packages, TIFF format is universal, and for modeling purposes, an image that is about 300 x 400 pixels will suffice. Sometimes an image this large will bog down older systems, and sometimes this resolution will not be nearly enough to get the detail required for the model you are trying to build. These decisions have to be made on a case-by-case basis. The best results for using image planes come from getting two or three images of the object that is to be modeled shown from different orthographic views and having these images scanned at identical resolutions and dimensions to each other. One trick I use when scanning image planes is to have the images I am scanning lined up on a single piece of paper in the exact orthographic layout that I want them to appear on the screen (Figure 8). I scan the entire sheet at once. When I crop the images to load them into individual windows on the screen, I use guides or rulers in my paint program to crop the images to ensure that they will have the same edges that create the sides for each image. For example, if you are creating three views, with the top view directly over the front view and the side view directly to the right of the front view, the left and right margins of the top and front views should be identical, and the top and bottom margins of the front and side views should be identical. For this to be truly exact, the height of the top view should exactly match the width of the side view. Paying attention to small details like this early in the process will save you a lot of work down the road.

[Figure 8] Drawings laid out in orthographic mode.

When loading the image planes, the modeler should begin with a new file and a new set of viewing windows set to default viewing size for all windows. The reason for this is that when you load an image into your file, most modeling packages will scale the image to the existing window size. If the file has already had the windows resized to another viewing angle or dimension, the planes will load in at a different size, and all your work to get the images scanned at accurate sizes will have been wasted.

When you load the appropriate images into the appropriate windows, and the edges line up along the appropriate sides, you are almost ready to begin modeling. First, however, you should make some decisions about what types of surfaces will be constructed and where these surfaces will be placed.

3D Reference Material
3D reference material refers to processes that sample data from actual objects and make the data accessible in 3D applications on the computer. These processes generally fall into the categories of 3D digitizing and 3D scanning. 3D digitizing and 3D scanning result in the creation of a digital version of an object that exists in the real world.