ATOR (Arc-Team Open Research).
The blog spreads tests, problems and results of Arc-Team research in archaeology, following the guidelines of the OpArc (Open Archaeology) project.
I received many feedbacks for the two posts about gvSIG 3D (gvSIG 3D and gvSIG with SfM data). I think the most important thing about the possibility to import 3D data in gvSIG with the obj format is that in this way we can import the two main kind of 3D data normally we have in archaeology:
3D documentation
3D reconstruction
Considering as fourth dimension for this data the value t (time), so that each single point has three spatial dimension (x,y,z) and a temporal dimension (t), we see that in archaeology the concept of documentation and reconstruction are very different.
In this short movie, in which I registered in gvSIG 3D the two 3D dataset I used for the test, it is possible to understand better this difference.
The burial is a 3D documentation, done in March 2010 and recording the situation in which we found the archaeological evidence after its deposition and all the post-depositional alterations. From a 4D point of view its time value (t) is March 2010 and it is connected with a single event: the discovery of the burial, which archaeologically can be considered as the last event in the "micro history" of the object.
The church is a 3D reconstruction which hypothetically describes the building in one of its "life cycle" stages, after its initial construction, and, more precisely, during the XIX century. From a 4D point of view its time value (t) is XIX century and it is connected with a period (after the architectural changes of the XVIII century and before the minor building modifications of the XX century). In short it is a hypothetical reconstruction of one of the post-depositional alterations of the object.
Another difference between this two kind of 3D data regards the techniques with which the 3D model are done. The burial was documented with Structure from Motion and Image-Based Modeling techniques (Python Photogrammetry toolbox), while the church was reconstructed with a 3D modeler (Blender).
The final difference is related with the normal work-flow of an archaeological project: the 3D documentation is done during one of the first stages, consisting in the archaeological excavation, while the 3D reconstruction is done just at the end of the whole process, after analyzing all the collected data.
In other words the main news about gvSIG 3D, from an archaeological point of view, is the possibility to handle in a GIS 4D data (x,y,z,t), following the natural evolution in the discipline methodology.
The presentations that impressed me the most during the workshop "Low cost 3D: sensori, algoritmi e applicazioni" (Trento, 8-9 March 2012) were the those of FBK's researchers and especially: "Tecnologia TOF per 3D imaging – low-cost o no?" (L. Gasparini, D. Stoppa) and "Caratterizzazione di sensori attivi e passivi low-cost" (F. Menna). One of the topic of these contributes was Kinect and the level of detail, accuracy and precision this instrument can reach. In particular it was said that using Kinect with a distance of 50 cm it is possible to record 3D scenes with an error of more or less 2 mm.
Alessandro and me already tested Kinect in ArcheOS (on Ale's laptop) during our teaching experience in Lund University, but in that occasion we did not check the level of accuracy. For this reason Alessandro compiled RGBDemo on my laptop during the workshop and, thanks to the coffee break, we tested it with some researchers reaching an accuracy of 1 mm.
This evening I repeated the experiment at home and here is the video of RGBDemo Reconstructor during data acquisition:
The yellow square you see in the movie is a normal folding meter and its side is 20 cm long. Here is a more detailed picture of it:
In this other movie I checked the accuracy I reached within MeshLab. When I measured the side of the squared the result was 0.198 m (better seen in full screen...).
I think this level of accuracy is more then enough for archaeological applications. Anyway I will go on with other test in the next months, hopefully with something more professional than my living-room :).
we are testing the powerful software MicMac and Apero. The calculation is really fast and the result is amazing. We hope to integrate in ArcheOS as soon as possible.
We tried with the example data (picture below). The next step will be to use our pictures.
Just a fast post to confirm that it is possible to import SfM data in gvSIG 3D, like I supposed wednesday.
I tried again with data from Arc-Team's excavation of St. Andrea's church in Storo (TN, Italy): in the image you see the documentation of "tomba 2" ("grave 2"), done with Structure from Motion techniques (Python Photogrammetry Toolbox). I elaborated the pointcloud in Meshlab, obtaining a textured mesh. Then I upload the file in gvSIG 3D.
Finally we have a fast way to import 3D documentation (PPT and Meshlab) and reconstruction (Blender) inside a GIS (gvSIG)!
Today I tried to play a little with gvSIG 3D and I have to say that it is really a good extension for this GIS. We should insert it in the next gvSIG package for ArcheOS Theodoric!
Anyway we have to go on with new test to explore all the different possibilities of this kind of tools in archaeology; by now I just imported a 3D model I did in Blender for the excavation of S. Andrea's church in Storo (Italy, TN), like you can see in the picture below.
To import the model I used an .obj file, which I exported directly from blender. Next time I want to try to import a mesh from some SfM data...
I finally found a good FLOSS to do videotutorial for ArcheOS in flash. It is called Salasaga and it works fine. It has more or less the same functionality of Wink, which gave me some problems under GNU/Linux. By the way Wink is a nice software, but being a simply a freeware, we cannot redistribute it in ArcheOS and, most important, the source code is not accessible.
I tried a little Salasaga to do a first videotutorial, which I posted here (in the DADP wiki). I think it will be a good resource for ArcheOS Theodoric (hoping in some feedbacks from the community in order to produce a set of videotutorial to spread knowledge in using FLOSS for archaeology).
Here you can see a screenshot of this software at work:
