ArcheOS Hypatia Virtual Globe: Cesium

Hi all,

I am starting here a series of short post to show some of the features of the main software selected for ArcheOS Hypatia, trying to explain the reasons of these choices. The first category I'll deal with is the one of Virtual Globes. Among the many available options of FLOSS, one of the applications which meets the needs of archaeology is certainly Cesium. This short video shows its capability of import geolocalized 3D complex models, which is a very important possibility for archaeologist. In this example I imported in Cesium the 3D model (done with Structure from Motion) of a a small boat which lies on the bottom of an alpine lake (more info in this post).

Soon I'll post other short videos to show other features of Cesium. Have a nice evening!

OpenMVG VS PPT

Hi all,

as I promised, we are back with new post in ATOR. We start today with an experiment we wanted to do since long: a comparison between two Structure from Motion - Muti View Stereoreconstruction (SfM - MVS) suite. The first is Python Photogrammetry Toolbox, developed by +Pierre Moulon some years ago and integrated in ArcheOS 4 (Caesar) with the new GUI (PPT-GUI) written in Python by +Alessandro Bezzi and me. The second one is the evolution of PPT: openMVG, which Pierre is developing since some years and that will be integrated in the next releases of ArcheOS.

Our small test regarded just four pictures taken with a Nikon D5000 on an old excavation. We want to point out the speed of the overall process in OpenMVG, which gave a result compatible with the one of PPT.

In the image below you can have an overview (in +MeshLab) of the two pointclouds generated bye the different software: openMVG processed a ply file with 391197 points, while PPT gave us a result with 425296 points.

Comparison of the two models generated by opnMVG and PPT

The main different stays in the processing time. In fact, while PPT needed 16 minutes, 11 seconds and 25 tenths, openMVG complete the model in just 3 minutes, 28 seconds and 20 tenths.

Here below I report the log file of openMVG, where you can see each step of the process:

STEP 1: Process Intrisic analysis - openMVG_main_CreateList took: 00:00:00:00.464
STEP 2: Process compute matches - openMVG_main_computeMatches took: 00:00:01:13.73764
STEP 3: Process Incremental Reconstruction -  openMVG_main_IncrementalSfM took: 00:00:00:47.47717
STEP 4: Process Export to CMVS-PMVS - openMVG_main_openMVG2PMVS took: 00:00:00:00.352
STEP 4: Process Export to CMVS-PMVS - openMVG_main_openMVG2PMVS took: 00:00:00:00.352
STEP 5: Process CMVS-PMVS took: 00:00:01:25.85958
--------------------
The whole detection and 3D reconsruction process took: 00:00:03:28.208258

We will go on in working and testing openMVG, hopfully posting soon news about this nice software.

Have a nice day!

Acknowledgment

Many thanks to +Pierre Moulon and +Cícero Moraes for the help!

Digital Archaeology at Lund University

This year, as usual since 2011, +Alessandro Bezzi and me taught some lessons during the course "Archaeology and Ancient History: Digital Archaeology, GIS in Archaeology" at Lund University, held by +nicolò dell'unto. We used the opportunity to update the presentation with which we always start the first lecture. Here below you can see its last version, done with impress.js (just click on the first slide and us the spacebar to navigate).

For a better view, click here

The main topic is digital archeology (or "computational archeology", as it is also known in Italy). 

Initially we define five main operations that are common to any archaeological project: data acquisition, processing, management, analysis and sharing. The first three steps refer to the documentation work-flow, while the last three actions are related with the real research process (of course data management is in common with both of the phases).

Thereafter we analyze each step, starting with data acquisition, which is mainly based on hardware devices. During this operation are normally registered two elements, points and pictures, in order to virtually recover what the archaeological excavation is destroying. With points and pictures it is possible to document objects (artifacts and ecofacts) and actions (basically the archaeological samplings), and their elaboration or, in some cases combination, allows the researchers to record lines, polygon, 3d surfaces and real volumes, to register also the most complex elements of the archaeological record (layers, structures, etc...).

On the contrary of what happen with data acquisition, data processing is mainly based on software. Nowadays it can be divided into two orders of operations: standard procedures (raw coordinates elaboration, 2D photomapping, 2D vector archaeological drawing) and advanced techniques (3D restitution, volume calculation and 3D modeling). The very first and basic step to visualize recorded data is to elaborate the raw coordinates, registered with a total station or a RTK GPS, into a GIS readable code (e.g. CVS or WTK). Combining points and pictures is also possible to create georeferenced photomosaic, using a photomapping techniques (e.g. the metodo Aramus, the Khovle method or the newest Corte Inferiore method). Once obtained a complete georeferenced photomosaic it is possible to use a GIS to draw over the raster level, using one or more vector layers and to connect them with a database. Advanced techniques of documentation are more directly related with 3D and can be based on different methodology to extract morphological, topological and metric informations from one or more pictures (e.g. SvR, SfM, IBM, 3D photogrammetry, etc...). With these informations it is possible to calculate the real volumes of the elements of the archaeological records and use this data to reconstruct the depositional and post-depositional processes, using, when necessary, 3D modeling. Normally, during the different work-flows that can be involved in data processing, many kind of informations are elaborated with raster, vector and voxel graphic in 2 (x,y), 3 (x,y,z) or 4 (x,y,z,t) dimensions. The final aim is to set up a system which is able to handle such a variety of data and this system is the GIS.
In fact GIS software, combined with DBMS, are extremely useful during the data management phase, exactly for their capacity to handle different kind of informations (as many as are the disciplines or sciences which help archeology in its task). The use of such instruments helps to optimize the research, especially in comparison with the traditional techniques, not only during data management, but also during the more delicate stage of data analysis (when most of the cognitive processes are involved).
Among other things, in this fourth step, it is more evident the importance of using open source software and tools to maintain a continuous control on every single process of a study that can lead to the elaboration of new theories. Of course, not all the the analysis are equally sensitive under this aspect: for the simplest researches (anastylosis, building techniques, basic geomorphology, etc...) it is not strictly mandatory to know the source code of the applications, also because in these cases the main examinations are done directly by humans. On the other hand, for more complex studies (landscape archeology and Cost Surface Analysis, statistics, advanced geomorphology, etc...), it is very important to have a complete access to  the formulas and algorithms used by the software in order to keep an human control and do not completely delegate to the computer, among difficult quantitative calculations, also more delicate qualitative investigations (in which the human operator is still essential). In this way it is possible to correctly study all the different informations collected during the archaeological research, considering, at the same time, future integrations (GIS is an open system under a temporal point of view). The last goal of data analysis is to share results with the (scientific and non) community, which is the best way to improve the archaeological discipline itself, especially exploiting the potential of internet.
This lead us to the final step of an archaeological project (data sharing), which can follow different channels, like traditional publication, e-publication (e.g. webgis), exhibitions, etc... The most important thing, at least for scientific disclosure, is to grant a public access to all the informations used for the study (not only the filtered data, but also the raw data), in order to propose new hypothesis and (at the same time) give the all the necessary elements to verify them (no dogma, no authority principle).
To summarize the meaning of this contribution, considering archeology as a science (empiric approach) and a humanity (speculative approach), we can see how computational archeology helps to improve the scientific (empiric) approach, which is often underestimated, granting a more objective data acquisition and processing respects traditional techniques, especially during the critical phase of the archaeological excavation. In fact, unlike scientific experiments, the archaeological excavation is unrepeatable, being the most destructive approach of the discipline (and, at the same time, the most important).

PS

All the screenshots were done with ArcheOS. Some of them are related with really old projects, slowly we will replace them with more updated images...

Arc-Team and Antrocom NPO start "Taung" project

"Taung" project starts: its aim is the craniofacial reconstruction of the fossil known as "Taung child", a specimen of Australopithecus africanus discovered by Raymond Dart in 1924 in a quarry near the town of the same name in South Africa.

"Taung" is a collaborative project between Antrocom non-profit organization, an association for anthropological studies, Arc-Team, a company that operates in the field of cultural heritage, and Cicero Moraes, an expert in 3D modeling applied to the forensic context.

The Museum of Anthropology of the University of Padua has provided the casts of its collection to the experts of Antrocom NPO and Arc-Team. Among the objectives of the project: to evaluate the applicability of the used method to the reconstruction of faces of contemporary human beings, to the paleoanthropological context and to create a database of examples of application of modern techniques of digital reconstruction to the anthropological context for research and popularization.

The researchers decided to work through a three-dimensional survey of the cast of Taung child at first, and then they decided to reconstruct the facial muscles of the skull through the observation and comparison of DICOM scans of primates.

In particular, the three-dimensional survey of the find was made through techniques of Structure from Motion and Image-Based Modeling (SFM / IBM), using only free and open source software (Python Photogrammetry Toolbox). For the digital reconstruction of the facial musculature researchers chose open source programs (including Blender), modeling using the technique of "metaballs" the needed muscle bundles, while they will be used mainly the free software InVesalius for the comparison with DICOM data of other primates.

The project is located in a wider context of research that aims to explore the application of digital techniques in the museum context, with particular attention to the findings of anthropological nature.

The search results will be released as soon as possible in turn under an open source license and therefore freely distributed. Antrocom NPO and Arc-Team would like to thank, for their invaluable cooperation, the Museum of Anthropology of University of Padua, in the person of the keeper, dr. Nicola Carrara, and the Centre for Museums of University of Padua.

Antrocom non-profit organization promotes and encourages the development of studies of physical and cultural anthropology, working in scientific research, education, training and in the popularization of anthropological sciences. The Association is careful to perceive and enhance both the local tradition that the new technological perspective applied to anthropology.

Arc-Team sas is a company based in Cles (TN, Italy) formed up by young archaeologists and anthropologists working in the field of cultural heritage, characterized by wide-ranging collaborations at national and international levels. In particular, it deals with archaeological excavations, documentation and digital modeling (2D and 3D), GIS geoarchaeology, WebGIS, paleopathology, anthropology and musealization.

3D for archaeological finds

One of the most common question we receive about SfM and Computer Vision techniques is: "is it possible to document in 3D also small objects like archaeological finds?". The answer is yes, it is, and there are two possible ways:

1. putting the object to record on a turntable (with a black panel as background) and taking pictures from a fix point  (as I described in this post)
2. taking pictures walking around the object (the easiest way)

Untill now, in both cases, it is better to use Bundler 3 instead Bundler 4 (that seems to have some problems with symmetrical objects). Anyway for option 2 there is no need to "erase the background" so it is possible to use also the newest version of the sofware (which is the one inside Python Photogrammetry Toolbox). This is because other objects in the background can help Bundler to find the right position of the cameras for every picture. the image below is an example of this situation: I took the photos walking around the archaeological find, which was simply placed on a piece of wood (over a normal A4 paper, for metric references).  

3D documentation of arcaheological finds with Bundler and PMVS2

The archaeological find in the picture comes from the mission in Khovle Gora (Georgia) of University of Innsbruck, Department of Ancient History and Near Eastern Studies, (Walter Kuntner and Sandra Heinsch) and Javakhishvili Tbilisi State University (Prof. Vakhtang Licheli).