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:

You'll need to visit the Autodesk website at http://www.123dapp.com/catch. Here, you will be able to download the application for use on a PC, or use the web app if you're using a Mac or Linux OS. A free account will need to be set up with Autodesk, or you can use your social networking account, such as Facebook, to log in.

You'll also need the folder containing the series of photographs of your objects.

Connect to the Internet, open 123D Catch, and sign in to the Autodesk server, if necessary. Proceed as follows:

A photograph is basically a flat two-dimensional record of a three-dimensional space. It contains most of the information of this three-dimensional space, except for the data needed to provide information about its depth. By taking more photographs, we supply more information. When we took a series of photographs around our object, we not only recorded the shapes, colors, and textures, but also mapped out a three-dimensional scene.

When the photo files are uploaded to the Autodesk servers, their system begins the tedious process of correlating all the images together. It first determines the camera position and aiming angles of each photograph and then uses a system of triangulation to map out the space. It then creates a 3D mesh of your scene from this information.

You'll need a processed 3D scene of your object. Autodesk will e-mail you with a notification that your capture has been successful. A link will be provided to download the Photo Scene data file (.3dp). The filename will start with the word Capture, the date it was created, and a series of numbers. Create a new folder and download the file into it.

Open 123D Catch and proceed as follows:

When you opened the Photo Scene data file, two things happened. First, there were additions made to the folder where the .3dp file is stored; photos that comprised your scene were added, and another folder was created with the same name as your .3dp file (this folder contains two Autodesk files that we should not touch). Secondly, the scene was loaded on your workspace.

This scene includes a visual track of the movements you made when photographing your object. This enables a convenient review of the photos for the purpose of editing or fixing stitching problems that may occur. Stitching is the term that 123D Catch uses for describing the correlation of photos in a sequence. We'll examine stitching in greater detail in the next recipe.

Hopefully, you don't have any stitching problems with the four objects you scanned, but we will need a photo sequence with stitching problems for this recipe. There's an easy way to illustrate the repair of unstitched photos, even with a good processed scan. Choose one of your Photo Scene data files for the following recipe, and make a copy of the folder and all of its contents. Use the copy for this recipe.

Open 123D Catch and sign in. Open an existing capture and proceed as follows:

For our recipe, we intentionally unstitched a photo from our sequence. This gave us a situation to repair it using manual stitching. Sometimes, we may find that it's important to unstitch a photo that has been incorrectly processed by the Autodesk server. This can occur when similar sides, such as the sides of a cube, are confused in the interpolation of the scene and an erratic camera track is produced. Sometimes, unstitching a photo out of sequence and restitching it where it belongs will solve the problem.

There are situations when the incorrect exposure or focus of an image is undesirable. This can be the case when the output is for export as an animation. By unstitching the problematic photo, the result will be better.