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3D printing with RepRap Cookbook
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The 123D Catch scanning process requires the use of an ordinary digital camera to take a series of 40 or more photographs while moving around an object. Virtually, any stationary object can be chosen, provided that you have a complete 360-degree unobstructed view around the object, and it can be photographed with good lighting.
For the following recipes to be more useful as a learning exercise, it will be helpful if you find objects that are similar to the ones shown in the following image:

The following are the specifications of the objects shown in the preceding image:
It is important to choose objects that do not contain protrusions, which span far out from the object, such as the outspread arms of a standing figure. It's also best to avoid large recesses or holes. Simplicity of the object's form is best when making your choice.
Acquiring objects with a variety of sizes and complexities, similar to the preceding examples, will help us test the basic capabilities of 123D Catch. They will also help us test different problems in the 3D printing process.
For this recipe, you'll need a digital camera with a good focus and exposure control. You'll also need the four objects that you have selected for scanning. For smaller objects, a flat surface such as a tabletop is required.

Prepare your work surface for the smaller objects. Try to avoid a shiny surface where there can be a lot of reflection. If possible, mask out a work area with a sheet of newspaper. This will provide a dull surface. For all of the objects, make sure there is consistent illumination. Don't use flash! If you are photographing outside, an overcast day or shade is preferable rather than the harsh lighting of direct sunlight, which can create deep shadows.
We will proceed as follows:


When we photograph smaller objects, the camera's depth of field is short, and this will generally produce a blurred background. It's good to have an initial series of photographs that retains the sharp detail around the object. By placing a smaller object on a newspaper, the printed lines will act as registration points and help in sequencing all of the photos in proper order. With the larger objects, the camera's depth of field will generally be longer, and the background will be in focus, providing enough background information for registration. Moving around the object twice and photographing with high and low angles will help record more detail of the object's form.
Sometimes, when photographing an object, there can be a glare on the surface from a light source that is improperly angled or is too close to the object. If possible, adjust the object or the light source to remove the glare. Sometimes, a shiny surface will have reflections, which can cause distortion. The following are several solutions that can be implemented:
In this case, the toy block was reflecting too much of its surroundings. 123D Catch interpolated the reflections as holes. By painting the block grey, the block was properly modeled, shown as follows:

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