OS and FS in archaeology

[Luca Bezzi]

Benjamin wrote:

> Good news! Is there an OS software for laserscanning?

   Yes, there are some OS/FS for laserscanning. Most of them are developed by the
Stanford University. The main software is Scanalyze, but there are some
interesting other software like ScanView (to visualize data), and many other. In
our team the expert in lasersacnning is Rupert, so maybe he can answer better
than me to this question... He worked in a society called No Limits Geodata, and
he used Riegl laserscans with Scanalyze (if I remember well).

> Have you looked at SAGA GIS? It seems pretty powerful in the beta version 2.

   Yes, in ArcheOS there was already Saga (I don't remember which version). We
chose it because it is pretty good with 3D data and very seample, so I think that
it is a good choice for new GIS users, but personally I prefer GRASS. In ArcheOS
1.1 there is Saga 2.0 beta.

> What I was missing in the old version of ArcheOS was some good sample
> data for each application to play with.

   Unlucky the problem with sample data is (for us) the same we had in spreading
archaeological information: by now we have no data we can share, till the
sovrintendence (or the university) will publish the excavations in which we
worked. So in ArcheOS (by now) there is only Spearfish as sample data (maybe you
know some other public data we can insert, or you have some you can share... It
would be very useful).

> I was also a bit stupified by the fact that I was greeted with a very
> blank desktop void of even a menu bar. I had to find out that you need
> to move the mouse cursor to the bottom to popup the starter menu ...

   We chose a menu bar like this cause it was close to Windows (ArcheOS was
developed for new GNU/Linux users...). We can choose to change it, it is not a
great problem.

> Maybe put some presentations, PDF documents etc. on the Desktop
> to get people started?

   I would like to put some presentations, and tutorial in ArcheOS, but we have
very few time to do it. Normally we work in the excavation till evening, so we
cannot work with the computer till night... We would like to have some help from
the community. Every one that wants to write a tutorial can send it to us (or
publish it on internet, maybe with FDL license ) and we can insert it in ArcheOS
(of course, under the name of the author). We (my brother) only wrote a small
tutorial about Stereo, that we thought was the most difficult software to use (it
is inside ArcheOS).

> I looked at your presentation and was delighted by the progress you are
> making with Voxel representations.
> Some points I would like to note (re. page 11 of the PDF presentation):
> The VTK-model you are creating using r3.out.vtk seems to be a bit of a
> "fake"? As Sören explained to me, what it does is take a GRASS voxel map
> and squeeze/stretch the individual voxel columns so they fit between the
> two boundary surfaces (top and bottom).
> Apparently the preceeding r3.mapcalc command just creates a cube of
> voxels to be fitted between the surfaces. Why do you store each voxel's
> individual 3D position in the output? Given that r3.out.vtk resp.
> the VTK engine manipulates every 3D cell in the fitting process
> individually, this would invalidate their 3D coordinates in the
> paraview display, anyhow (yes/no)?
> So why don't you just do something like this:
> r3.mapcalc "layer1=1.0"
> and then glue together the individual layers in paraview so you can
> at least operate on the layer numbers?

   I am not sure I understood what you mean. In page 11 of the PDF presentation
we show the formula we used to export from GRASS a surface ("fase 01" was the
first part of the excavation, but we did the same with fase 30 - the last part
-). It is a voxel, but not a volume, only a surface. In page 12 there is the
formula we used to do the same with the vector data (3D extruded surfaces that
represent the founds of the excavation, only brocken pottery, bones and a
"fibula"). Finally in page 13 there are the formulas we used to export "real"
volume voxel. we followed the indications of Soeren (if you want I think my
brother still has the email in which he explain us how to do, I can send it to
you). I don't think that this process can invalidate the coordinates of the data
cause when we load all the different data in Paraview, everything was in the
right place (the two surfaces, the founds, the volume model of the layer, the
little vase reconstructed with Blender ...).
The problem is still the same: this data are not "mine", so I cannot share them
trough internet (officially the owner of the data is the University). That's why
I change a little bit the data ... I was speaking about this with my professor
and I obtain unofficially the permission to put my thesis on internet. I think
this is a first step. I hope soon I can put all the data on internet (I need only
some time and to make clear who is the real owner of the data: sovrintendence or
university? It seems actually there are some problems about it)     

> In addition: how do you represent irregular borders at the *sides* of
> your excavation trenches?

   Do you mean "breaklines". I never had this problem in Grass till now, I will
try to solve it when I will need (I hope soon). The borders you see in the
presentation are so regular cause this data came from my thesis. It was a
mircrostratigraphical excavation of two graves (this is one of them). The graves
were discovered 20-30 years ago, than closed in a wooden box and transported in a
laboratory. That's why the borders are so regular, they are the border of the
wooden box (probably the real layer was a little bit greater...).
I hope I can try to use breacklines in the excavation my brother is doing now for
the Arc-Team, but we will need time to process the data... Anyway we will test
very "hardly" OS/FS software (ArcheOS) in the excavation we are preparing with
the University of Innsbruck. It will be in Aramus (Armenia), and ArcheOS will be
the official OS. I think it will a great opportunity to test it (the project is
very big).

> While your approach is cool to use with paraview, it seems to me
> that for GRASS-based analysis we need a module that performs a
> 3D-interpolation in the GRASS voxel space itself.

   I would like to have such a module, I prefer to use less software when I
can... The Grass users often worked with Vis5d or Mayavi (for voxel) and PovRay
(for 3D reconstruction), we chose Paraview and Blender... We spoke about it with
Markus and now he seems to like Paraview very much. Even the guys of RIADE seems
to want to stop in developing Nviz and start to work with Paraview (they are an
italian software society that was developing Nviz). But I think that if someone
will work for a module directly inside Grass would be nice.

> Do you have any experience generating DEMs of layer surfaces using
> stereo photogrammetry? I would like to replace the tedious total station
> point measurements with some quicker mode of data capturing and
> stereo photogrammetry looks like a promising candidate.

   Yes, I worked with stero photogrammetry very much, but unlucky I started when
I was still working with closed software. I often used Erdas to do such work. It
has a very good module (Orthobase) to reconstruct 3d surface from a stereopair,
and it is pretty simple to use. But I hope that soon efoto can do the same. I
will test it very soon (I am preparing a lection in Innsbruck for the 10 of
June), and I think that we will test it in Armenia too. We tested efoto only till
the 0.0.4 version (you could use it only till the external orientation), but the
0.0.5 is more complete (there are new modules).  We tested Stereo too. It is very
good, but too instable, and has not a module to find automatically common points
in the stereo pair (a very important module, if you don't want to lose too much
time).

> Well, those people are out of the race already. No need to worry about
> them. Let's focus our resources on productive cooperations and simply
> ignore those computophobics.

   Unlucky I think they are still the majority in Italy.

> Yes, but projects like Linux, OpenOffice and Firefox are paving the way
> very fast. Let's call open source open source. People will get used to
> it soon enough.
> This is exactly the sort of thing that is blocking progress in
> archaeology. It is questionable if a law like this could be upheld
> when challenged in a higher court, especially on the EU level.
> In Germany, the problem is more complicated, as heritage
> management is fragmented on the federal level. Definitely plenty
> of work for some good lawyers all over the world. But who can afford
> them?

   Yes, this is really a great problem... As I already said, I didn't study yet
the argument, but I think that most of the law about it in Italy are very old
(but maybe there something new in the "Decreto Buttiglione"?, I didn't read it
yet...). I know a real case in which they are fighting about the publication of
one single found, and it seems that they have to go back with the law till 1907
or 09. That's crazy. In another case a guy published a wrong study only cause he
could not see a new excavation in which there were new founds that showed his
theories were wrong. I mean that he knew his theories were wrong, cause he
unofficially saw the founds, but officially the new excavation didn't exist cause
it was not yet published. This not only make the research slower, but even wrong.

Sorry for the long email,
best regards,
Luca   


Luca Bezzi

Arc-Team
Archaeology & Free Software
http://www.arc-team.com/
luca.bezzi@arc-team.com