Wednesday, 3 December 2014

Space archaeology

Per aspera ad astra

When you start a new research you know where your path begins, but you do not know where it will end (and where it will take you). 
As many of you knows, we work also with 3D printing of archaeological objects: here (1 and 2) is the two post +Leonardo Zampi wrote about the Taung Project and here is a post regarding some Augmented Reality applications, in one of which a 3D printed skull was used (look the first video).
Most of these experiments are connected with the open source exhibition "Facce. I molti volti della storia umana" (please, do not forget our crowdsourcing campaign: send us your images!). For this event, whose English title is "Faces. The many aspects of human history", we planned to used 3D printed objects for different Augmented Reality applications and to expand the accessibility to the digital exhibit for the visitors (reducing the restrictions connected with disability). This post reports an preliminary overview of the event (done during the European Academic Heritage Day 2013), in which are presented the main topics of the exhibition, the problems and the solutions we planned to apply (sorry, the slides are in Italian; I will translated the text ASAP).
Today, working on a new research for this exposition, I tested different possibilities to reconstruct a 3D from a unique image. Normally our (Arc-Team) work-flow starts with a 3D model obtained from Structure from Motion and Image-Based Modeling (using different software) or from x-ray Computer Tomography (like for the paleoart or mummiology projects), but in archeology can happen to use Single View Reconstruction techniques when there are no other solutions. This post of +Cícero Moraes is a good example of a reconstruction in Blender based on perspective and vanishing points. Of course this technique is optimized for architectural documentation of structures, but is almost unusable for more irregular objects. 
To avoid this problem I studied different possibilities and I decided to use the same software, Blender, but in a different way. I looked in internet for an archaeological picture that could meet my requirements: not too simple, but with a correct light exposition. My problem in finding a good base image comes from the fact that the archaeological artifact photography has codified rules and normally the light source is located in the upper-left corner, otherwise bas-relief (convex) would appear as counter-relief (concave) and vice versa (due to the Hollow-Face optical illusion).
After a while I found this image, which has an almost correct light exposition (sorry, I do not know anymore the source of the photo and I did not find informations about the author).

The base image
I modified the picture with GIMP, in order to obtain a grayscale photo, than I imported it in Blender.

The grayscale image
There I used the "displace" modifier and I automatically obtained a fast 3D of the object (of course nothing comparable with SfM and IBM technique, but enough for my SVR needs).

The displace modifier
After some additional smoothing operation in Blender (you can directly use the related modifier), the model was ready to be saved as an stl file, loaded in Cura and printed in 3D.

The stl file in Cura
At this point I was ready to adapt the entire process to my needs in order to work for the exhibition "Facce", but here is were my research took a complete different way.
On my desk was lying a local newspaper in which was a photo of the Italian astronaut Samantha Cristoforetti, who is actually on board the International Space Station (ISS). Dr. Cristoforetti was born in Milano, but her family is originally form a town (Malé) very close to the one in which I live (Cles) and this is the reason why local press is following her scientific mission very closely. Reading the article I was thinking that it would be nice to print in 3D something that could be a tribute to her work and to the whole mission: something related with space exploration and archeology. Suddenly in my mind appeared a black and white picture, which probably most of you know and that dates back to July 20 1969, so I decided to test the process on this image and see the result.
I searched on the NASA website regarding the Apollo 11 mission and I found what I was looking for: the photo of the first footprints on the moon. I turned the picture into a grayscale image and I repeat the protocol of Single View Reconstruction with this data

The grayscale image
The video below shows all the work-flow and is a new videotutorial for the Digital Archaeological Documentation Project.

Of course the result has no metric, nor topographic value and it is more an artistic reconstruction than a 3D documentation, but this time it was just for fun and for a tribute to woman's contribution in space exploration. BTW on board the ISS astronauts are currently testing 3D printing in space (Made in Space).
If you want to print directly the .stl file I did, you can download it at this link. Otherwise in this post you can find all you need to do the process by yourself.
Have fun! 

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