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Scan3D

Description of the project

The purpose of Scan3d, as its name suggests, is to acquire the three dimensional shape of a real-world object. In particular Scan3D is a program that uses a set of pictures of the object, to obtain a VRML description of its surface.


This figure shows an example of what scan3d can currently do.

Introduction

First of all: for me is not so simple to write in English, so if you find errors or parts which are not well explained, don't hesitate and send me a corrected copy of this document.

This project is in its early stage of development, so it is incomplete, full of bugs and so on. There are still many things to do: so, if you think that you can give your contribution (every kind of contribution), you are really welcome! You can find a list of things to do under the main directory of the project (the file is named as usual: “TODO”).

How does Scan3D works?

I describe what instruments you need and how you should use them.

Scan3D require only a digital camera and a rotating plane. A digital camera is not so difficult to find nowadays. The rotating plane can be simply the tool you put under your TV to easily rotate it, but you can use whatever other thing lets you rotate the object around a fixed axis.

There are many suggestion I could give to you, but I prefer to begin giving a fast description of what you should do to “scan” an object. You should place the object you want to scan over the rotating plane. Then you should put the digital camera in front of the object. Now relax and take a coffee: you should take about 70 photos to obtain good results. The procedure is as follow: take a photo, then rotate the object by a precise fixed angle; now take another photo, rotate again by the same fixed angle and continue in this way until the object gets rotated by 180 degrees. I give you more details in the section “Suggestions”. Read it carefully.

What can you obtain from Scan3D?

Scan3D has some limitations. First of all it can't see the convexities of the sections it reconstructs. This figure gives a visualization of what this does mean:


This figure shows how Scan3D reconstructs the sections of the object.
NOTE: the axis of rotation is orthogonal to the plane which contains the sections.

This problem will be partially solved in the future, but now can give bad results for a large number of objects. Scan3D is not for those who want perfection (and want to pay for this!).

Second problem: Scan3D assumes that effects due to prospective are negligible. This means that it is preferable to put the object to scan far from your camera and use its zoom if possible. Don't worry too much: look at the following example: it has been obtained with an economic digital camera and with a few good ideas (find them in the section “Suggestion”!).


A view of the VRML file. This object required 72 photos.


What is the current status of the project?

Scan3D is still in its first stage of development. Many things need to be improved.

If you think you can help me, please, write to me!


Suggestions

A few suggestions:


Matteo Franchin
fnch@libero.it


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