Presentation: “Image-Based 3D Modeling”

Hi everyone,

One of the objective  of this blog is to promote the use of Close-Range Photogrammetry for the creation of fully texture 3D models to study, understand, record and visualize a particular type of object, building or monument.

So I recently gave a presentation at work (CPD event) to introduce and explain the very basic concepts of a photogrammetric survey, its advantages and limitations. Architects, engineers and  archaeologist were among the people who turn up for the occasion.

You can download a pdf version of the presentation here.

Please leave a comment. I need to know what you think.

Ciao e grazie!

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Close-Range Photogrammetry: A very short overview

Close-Range Photogrammetry has been used for many years to extract 3D measurements (xyz) from small to medium size objects (0m-100m). It is a reliable, portable and low-cost 3D surveying technique suitable for a large number of applications. Depending on the required final quality of the 3D model various types camera can be used:  professional metric camera for high precision measurement, more affordable but still reliable off-the-shelf SLR cameras, low-cost compact cameras or even cameras in mobile phones.

Photogrammetry is a non-contact 3D measurement technique which means that there is no physical contact between the camera (measuring device) and the object to be measured. Currently there are two main types of non-contact systems used to obtain 3D measurements: active sensor (laser scanners) and passive sensors (photogrammetry) sensors. During the past decade applications such as Architecture, Archaeology and Cultural Heritage , just to mention few, have shown an increasing interest in this technologies.

Sorry! Yet another important classification. I will try to put it simple. The process for obtaining a 3D model using photogrammetry can be: manual, semi-automatic or automatic and in general when automatic procedures are used a higher level of accuracy can be expected. Obviously there are other factors affecting the accuracy of the model but I will cover them in later posts.

So what are the most important steps to carry out a photogrammetric survey? The traditional pipeline is as follows:

1. Project Requirement
2. Network Design
3. Camera Calibration
4. Image Acquisition
5. Camera Orientation
6. 3D Measurements

That’s all for now. Check out the Event page where you can download some very interesting papers from the 4th International Workshop 3D-ARCH 2011. Please leave a comment if you have any thoughts or suggestions. Next, I am going out to take some pictures for my new post.

Ciao a tutti!

Photogrammetry

“Photogrammetry is the science, and art, of determining the size and shape of objects as a consequence of analysing images recorded on film or electronic media.” (Close-Range Photogrammetry and Machine Vision – K.B. Atkinson,  2003)

 

In 1480, Leonardo da Vinci wrote the following: “Perspective is nothing else than the seeing of an object behind a sheet of glass, smooth and quite transparent, on the surface of which all the things may be marked that are behind this glass. All things transmit their images to the eye by pyramidal lines, and these pyramids are cut by the said glass. The nearer to the eye these are intersected, the smaller the image of their cause will appear.” (Doyle, F., 1964. “The Historical Development of Analytical Photogrammetry”, Photogrammetric Engineering, XXX(2): 259-265)

Introduction

Welcome to the Image-Based 3D Modeling blog. If you started reading this blog it is likely that you are interested in creating 3D models from images for various purposes.

The blog is aimed at everyone (professionals and non professional) who wish to understand and apply the basic concepts of Photogrammetry. Professionals like surveyors, architects, engineers, heritage officers, archaeologists, conservation architects and many others still using 2D representations of 3D objects may be asking themselves the following question: Why do I need fully textured 3D models when all I want is a simple plan or elevation drawing? And why using images?

Well, fair enough! If you only have to draw that much. But what if you have to produce 3 plans, 4 sections,  3 elevations and in addition to that you are required to show in detail the condition of a damaged brick wall, several decorated architectural details like capitals or even a statue?

Why taking images?  Because they are an inexpensive and a rich data acquisition method from which you can extract both regular geometric shapes (e.i. a rectangular wall), free-form surfaces (e.i a statue) and color information.

The posts of this blog will cover all the different steps of the photogrammetric pipeline in a very simple and practical way with lots of external references to more detailed tutorials on the use of the various software and other published documentation. The blog is focused on the representation of real 3D object like a house, a  monument or an archaeological find where the 3D model is based on real measurements (Reality-Based 3D models).

See you soon for some real stuff….