Hi and welcome to our, a new lesson of the week six. The lesson number three. In this lesson we will talk about 3D reconstruction. In the previous one we talk about 3D survey. Basically, I go in the field, I perform my 3D acquisition, and I get my 3D model of a real object. In this case we talk about reality based model. In this lesson we are going to talk about a 3D reconstruction of objects, that there are no more existent. In this case we want, we can reconstruct them just starting from sources. But what are sources? Ancient writings, ancient texts, all the information that came from other similar context to the context we are studying. And for that reason, we are talking about source-based modeling. The most, the model resulting from the 3D survey itself can act as a source for our reconstruction being somehow a starting point for the measures. The need for a virtual reconstruction arises when, in an archaeological context, certain gaps appear due to damage or transformation. In other words, something disappeared and we need to restore it. 3D reconstruction is not only a digital matter. Virtual from the Latin term “virtus” is a synonym for potential and expresses the likelihood of a certain artifact having existed in the past. Okay. Something that is no more extant. The reconstruction practice started long before the introduction the computer. For example, here we can see a reconstruction of the Tabularium. In Rome from the 19th century. It is one of the so called Envois de Rome de la Accademie de France appeared when architects went to, to Rome to study and to reconstruct and so on. So, [COUGH] the 3D reconstruction is first of all an archaeological matter, and secondly a digital matter. For that reason, there is an archaeological theory, long before the introduction of the computer. That says somehow, something like this. We need to make a survey, and we go in the field, collect all the information about the monument, and the in the other hand, we have to collect all the sources available. The ancient drawings, the photos, the information from very similar context, and so on and so forth. But in the case of an ancient temple, we have to collect all the information about all the other temples in the same geographical area, and the same time span. We combine all these informations in the so-called dossier comparatif, as Pierre Gros said. The dossier comparatif collects all these informations and organizes them in a convenient way to be able to make the so-called eidotipi. The eidotipi are just sketches on paper or in digital formats where you fix the hypotheses you have in mind before starting to modeling the 3D space. The 3D model in this schematic however seems to be the last step, the output the output of the whole process. And it is somehow real for the, first approach of the virtual reconstruction. But within production of digital techniques in archaeology, something changed. [NOISE] We have a simulation of the reconstruction. I mean, in the case of this “sima” on top of an temple we can think to our reconstruction where the real objects acquired with a 3D survey can be replaced on top of a digital model. We acquired with a scanner or with our digital camera, a sima found in an excavation and we want to replace it on top of the digital model. But, when we do it, we have a lot of trouble. Because we can't put them in place in our 3D model. Simply because it does not fit in place. Like in a sort of a wrong block of a 3D puzzle. We have now something we can call incongruity. In our 3D reconstruction hypothesis, we have to change something. We have this incongruity. And the, this is a test of the goodness of our reconstruction. We have to modify or the dossier comparatif or the eidotipi or just search more information, more sources. What is important here is to state that the archeological reconstruction is an, an analytic and comparative process. The survey and the sources. So we analyze the context and we make comparisons also with other contexts, with other sites. [NOISE] We have to deal in the 3D reconstruction archeology with the so called black box effect. What is the black box effect? If you have a look to this 3D reconstruction of an amphitheatre you can doubt about what is real and what is an invention. So if you look to this reconstruction we are not able to say what is sure, certain, and what is just an hypothesis, or worst, just “evocative”. This is because, in archaeological research, the 3D model is often considered as a tool with which to synthesize and convey different elements, each one with varying degree of reliability. So somehow the process behind the reconstruction is unreadable. So we need to validate a 3D reconstruction somehow. Unfortunately no shared standards are present. Despite important things that have been done by the community like the London Charter or the Sevilla Principles, no shared standard is present. There are some approaches, but they are very different each other. So, we have we can call them as well like the generative layers with query-able elements. It's a long term. And contains different approaches, but the, in a nut shell, we can say that. We want to we can superimpose to our reconstruction just layers of colors to say more about this part of reconstruction. So something based, is based on objective information. Something on.. ..the consistence of the style, the consistency of deduction and so on and so forth. So we have degree, gradients of consistency, degree of certainly, levels and classes, and so on and so forth. Every researcher uses other names. Or we can use a quantitive method. So it is based on a single archaeological object and we have degree of reliability of consistency. So summing up the differences that in the generative layers with query-able elements, all the part of our monument, are divided according to the sources used to reconstruct it and in the quantitative methods based on the single archaeological object, we can state for each part of the reconstru, the reconstruction the degree, the relative degree of reliability. [SOUND] Okay. Let's see the 3D modeling planning. Now we have somehow clear. The methodologies and the big prob, the big issues in the 3D reconstruction. Now we have to approach it from a more practical point of view. We have to deal with the contents of a 3D reconstruction and focus on the geometrical accuracy of the contents themselves. And we have to choose the technical solutions and the communication style for our 3D reconstruction. Let's see, the 3D modeling plan from a contents point of view. When we can perform a survey a direct contact with the object we want to reconstruct, we have to choose the survey technique. From laser scanner to the traditional survey the choices are related to the budget and the real needs of the documentation. I mean the archaeological question we have to answer is not so important how does, how much does it cost? The technology and but exactly the question we want to answer to. So, When we work with documentation from other people, not our 3D Survey, we have to distinguish between the archeological documentation, a GIS Survey, reports from excavation, and the not archeological documentation. We can use a lot of data. A lot of documents as documentation for our reconstruction. For example, ancient cartography, iconema, historical photos, and so on and so forth. In this example, we can see the reconstruction of an environment, starting from the documentation from the 19th and 20 century. In this other case, we can see the projects from Michelangelo Buonarroti about Porta Pia, a project that was never been realized, but we can use this documentation to imagine, what was in the mind of this big artist. So, in the sample-based survey, only a few sample of the environment we want to reconstruct are available. These red dots. It is necessary in this case to use proper interpolation techniques to scientifically obtain the missing points, the missing part of this environment. And so we can get a reliable 3-D model. The geometrical accuracy is an aspect very important because we model something and we want to be accurate. But we have to take in mind that it depends deeply on the sources is not just a matter of methodology of the 3D modeling process. We need to have some sources accurate. In the case of the reconstruction of Porta Pia indeed in the 17th century. We can use some ancient drawings and we have here an example of the drawings used and the resulting 3D model made of different sources, different drawings. In this case, we can't get precise, accurate results from these drawings. Because we have not scale ratio at all, but sure we can take other important things. We can take the overall placement, the relative placement of the objects involved. So, in this case we have some trees and parks and the relative position of the houses and so on and so forth. So the technical solutions are very important and deeply influences the 3D reconstruction. Because the technical solution depends on the physical support which it is expected. So we are making a 3D reconstruction. And we will choose different methods.. ..according to different physical support, support at the end. So we want to make a video. We want to make a real time mobile app. A real-time desktop application. A web realtime app or just infographics, education panels, guides, manuals and so on and so forth. Okay at, in the end, the 3D modeling planning. From a communications type point of view. Our 3D reconstruction process from a technical point of view is deeply influenced by the user target. So we can chose to communicate to a specialist. To a generic user, or to a student. And it involves a lot of changes in the level of detail of the objects involved in the scene. And, so the formal language we use, and so on and so forth. For example, if we have to deal with a generic user. We can use also a toon style or if we have to talk with a specialist, we can use symbolic style of representation because it's not so important to make it so real. That we need to communicate in a proper way all the elements in a clearer way possible. So, in this lesson, we have seen all the steps involved in the 3D reconstruction of archaeological no more extant sites. So we have seen the theory behind the trigger construction processes, we have seen some case studies some typical scenarios of a survey, data collection and the most important things to take in mind during our 3D reconstructions. from a technical point of view and stilistic communication.
