maandag 8 februari 2016

Processing scans into 3D models (take 1), Kotryna Valečkaitė

Comparison of image processing software 1

Directly after receiving the scans on Tuesday we jumped into processing them into 3D models. To keep it clear we used “Hagrid”(obj. 5) as an example for all of the programs.
As noted in the previous post, this process has multiple steps and in order to gain the highest level of detail, a lot of tweaking is necessary.
The usual procedure goes as follows:
(0. Changing the .ima or .dcm files into program compatible format. Most of our scans were made in .dcm format which was not compatible with multiple programs: so far we tried RenameMaster, which did not work)
  1. Loading the .dcm or .ima files into a 3D processing program. These file formats actually contain only 2D information: the sections of the object. In other words, the 3D model is an interpretation of multiple sections and therefore steps between them might be visible, if the resolution is not high enough.
  2. Selecting threshold and filtering the right information. Depending on the program this step might be automatized. If not, it might be very heavy on your computer. Therefore, a device with a good graphics card and 16GB RAM is advised (it would work on 6 or 8GB RAM, but it goes slow and tends to crash often).
  3. Loading the 3D file into a volume renderer to get an editable mesh (.stl). 
To begin with, we started with Seg3D. This program did not want to read .dcm files, thus we only worked with test files, which were in .ima format. The interface was clear, but to extract minuscule details it needed a lot of filtering and playing with histograms. That was extremely hard on our computers (6-8GB RAM, 2.0-2.03GHz) and took over an hour to get a decent file. Moreover, the final result is given in .nrrd format which later has to be translated to .stl with the help of ImageVis3D. The file looked rather detailed in Seg3D, but the final .stl was worthless.Capture
Hagrid_Seg3D to ImageVis3D_128x128x54mesh_detail
Later on, we received a tutorial from an past student of our supervisor Maaike. It suggested using DeVide. Unlike the previous program this one works on the basis of visual programming. Thus all of the steps can be easily retraced. This program can directly export to .stl reducing the possibility of getting a very rigid mesh, like with Seg3D. Unfortunately, the program did not want to work on our computers.
After this failure we contacted one of the researchers in the faculty of Industrial Design Engineering. He adviced to try out the following programs:
  1. 3D slicer (open source)
  2. Avizo (paid, evaluation copy available after contacting the firm)
  3. Mimics (paid, evaluation copy available after contacting the firm)
The first of the list (3Dslicer) proved to be very user friendly (although it did not read the .dcm files). The information is collected automatically after choosing a preset and is quite precise. One can also select if to smooth the surface: both outputs are interesting in form, with the edgy one as an expressive interpretation of a kitschy object of the past. If used for the final product, more mesh post-processing is necessary
Hagrid_3DSlicer_nonsmoothedges_detail (1)
To be continued…

Making Choises, by Jorinde Smits

We had to make some choices since there were  a lot of bowls, plates, hair brushes and other ceramics. To distinguish them we gave them names. We joked about ‘Harry Pottery’ and decided to choose the names from Harry Potter characters. We based our choices at differences of advantages and interesting characteristics. Since we didn’t know how much time it would take to digitalise the cups and plates, we numbered them in order of importance.
We took in account the different types of advantages.

  1. Holes
    To make the cups useful again, we need to fix the holes.
  2. Details
    Some cups like Harmione and Hagrid have some nice details. Since the CT scanner is not that accurate we have to find other solutions for bringing those details back.
  3. Fixing techniques
    There are different ways used for fixing the objects. How can we translate those methods in our new design?
We decided to exclude the hair brushes in our process, because it has nothing to do with tableware.
1. Harry
Bowl with interesting holes the missing shards left. Diameter of +/- 15 centimeters.
2. Hermione
This one has some nice decorations. Diameter of +/- 12 centimeters.

3 DSC_0331

3. Ron
Here the advantage is to replace the three separate shards. Diameter of +/- 18 centimeters.

4. Ginny
Small plate. Missing a piece and two repaired cracks. Diameter of +/- 15 centimeters.

5. Hagrid
Kind of fruit bowl with lid. It has nails and glue as fixing methods. The cracks are really fragile, but as good as complete. Diameter of +/- 25 centimeters.

6. Dobby
We liked this small cup because of its small hole. Diameter of 5 centimeters.

7. Snape
This one is familiar to Hagrid, but much smaller. The one defect is the bottom which is fixed. The cup is complete. Diameter +/- 15 centimeters.
1 DSC_0305

vrijdag 18 december 2015

3D scanning and priorities, by Kotryna Valečkaitė

As the project slowly went into motion we had the first digitizing session in the laboratory of Geosciences&Engineering. Our group was provided with the luxury to first hand observe both micro- and macro-CT scanners in working. Both with their advantages and limitations, they gave us a new perspective of how to order and process given archaeological objects.
When Maaike came in with boxes full of ceramics from the Archaeological archive of Amsterdam, we understood that it was neither efficient, nor possible to scan them all. At this point selection was crucial. At first sight we had three main groups of objects: lice combs (highest level of detail), broken colored ceramics bound with metal strings (necessity to make more detailed scans to understand the technique) and sets of white ceramic tableware lacking multiple shards.
DSC_0381DSC_0307Detail hermione
The latter seemed to be the closest to the issues visible in the goal of the project. Yet the other two gave us interesting side paths which would improve overall understanding of the methods and possibilities of 3D scanning. Based on this, we made a queue sorted by importance, which would lead to at least one object of a group scanned.
After the first inspection of the digitized forms we were rather amazed that the precision of 0,3mm was not sufficient for some of the fine-detailed specimens. E.g. the combs lost their teeth, metal bindings were muffled, crack lines barely visible. Consequently we were offered to work with much finer machinery (micro-CT scanner) mostly used for small scale material research. Yet the time and money needed for this method led to only two specimens scanned: the finest ivory comb and a detail of a metal connection. In total we got 13 scans, excluding identical scans in higher precision. The notes and conclusions after this are as follow:
1. There are 2 CT-scanners in the Geoscience&Engineering laboratory:
  • Macro-scanner can be used to scan rather big objects, but the fine details are almost completely neglected; object is stationary, thus there is a small chance of damage. Precision 0,3mm.
  • Micro-scanner is very slow (1h per object) and has very limited object size: till 100-120mm in diameter; object is rotating, thus it needs to either be glued or fixed, which requires extra attention not to damage the object. Precision 0,03mm.
  • Both scan only the form and not color; they can detect cavities, but not slight changes in the material density
2. The digitized forms are saved as 2D images of section cuts in .dcm or .ima file format, which need multiple steps to be converted into editable 3D objects. Even though we were informed that it is a very quick procedure, to gain fine details it is necessary to have a powerful computer(16GB RAM) and correct software (which is usually paid).

Minor Advanced Prototyping: lets get started!

Welcome to the logbook of the research project Augmenting Prototypes: Smart Replicas. This project is a part of half year bachelor program “Advanced prototyping” in TU Delft.
Smart Replicas is the result of a collaboration between Archaeological department Amsterdam and design studio Maaike Roozenburg. The latter supervises 4 students preparing material for this blog: Kotryna Val (Architecture), Sander Pliakis (Industrial Design), Jorinde Smitser (Industrial Design), Irene(Industrial Design).
The focus of the project is the usage of CT scans to recreate and analyse repaired and/or unusable archaeological findings of everyday use.The aim of this is to replicate and improve given objects, while not losing the historical footprint. In other words, the blog will revolve on modern techniques of digital and physical reproduction.
The simplified planning will follow the scheme provided below. Each set of steps will be described in a weekly report, which will complimented with an occasional review of the field.

Objecten selecteren: Kammen

De derde en laatste groep die we geselecteerd hebben voor dit project zijn kammen. Een echt dagelijks gebruiksvoorwerp (luizen werden ermee bestreden) waar er veel van zijn opgegraven en die wonderschoon zijn in hun detaillering, materiaalgebruik (hout, been, ivoor, hoorn), slijtage en verval. Echt (technisch) uitdagende objecten voor de 3D scanner en ze bieden de mogelijkheid experimenten te doen met combinaties van ‘historische’ en high tech materialen in een design object.

Kammen uit de collectie Monumenten en Archeologie Amsterdam

Kammen uit de collectie Monumenten en Archeologie Amsterdam

KAT-34-9: kam in ivoor1625-1675

LU-6: kam in ivoor 1500-1650

PH-20-13: kam in Buxus 1525-1550

ANJ-1-46: kam in been

HE-3-1 kam in been

ANJ-1-3 kam in been, nagel paardenhoef 1625-1750

donderdag 17 december 2015

Objecten selecteren: gerepareerd gebruiksgoed

De tweede groep van geselecteerde objecten bestaat uit gerepareerd gebruiksgoed, uit willekeurig welke periode. Juist in de vindingrijke, aandachtige en vaak arbeidsintensieve manieren waarop mensen in het verleden gebruiksgoed repareerden is hun liefde voor bepaalde voorwerpen af te lezen. Daarnaast toont dit ook heel mooi wat de waarde van voorwerpen was en dat de arbeid die gestoken werd in de reparatie blijkbaar op woog tegen de kosten van een nieuw schoteltje, kam of kopje. Deze reparaties vormen een interessant uitgangspunt om in 3D scans en 3D prototypen te ‘vangen’ en te tonen.

maandag 14 december 2015

Objecten selecteren: 'industrieel' aardewerk

De eerste groep van objecten die ik geselecteerd heb bestaat uit vroeg industrieel aardewerk. Dit is het echte ‘niets aan de hand’ dagelijkse en onopvallende gebruiksgoed van de 19e eeuw. Juist dit aardewerk is alleen uit opgravingen ‘over gebleven’ en komt nauwelijks voor in museale collecties. Op deze opgegraven voorwerpen zijn goed de sporen van productie, gebruik, slijtage en afdanken terug te zien. Deze sporen wil ik een hoofdrol laten spelen in nieuwe ontwerpen.
Hier onder kun je een selectie van deze objecten zien: (zijn ze niet bloedstollend prachtig!)