Revision of two scanning methods, by Kotryna Valečkaitė

As promised, we would give the summarized results for the two scanning sessions that we had: with CT scanners and with Artec Spider scanner.

Part of the results of the latter unexpectedly disappeared during the post-processing. The scan which promised the most for us, Hermione handle detail, was among the missing files. We hoped to get better results of the floral ornament and combine it with the CT-scan body, only the chosen comparison model and Harry survived.

As seen, for the comparison we chose the finest model we had. The lice-comb teeth were approximately 0.5 mm diameter with even smaller gaps between them. Due to this, the scanning technique used by Artec Spider could never achieve a proper result: too much was not visible, even with the precision of 0,05 mm. In other words, the grid which the range finding device projected could not be interpreted in the gaps and the result was a block with a texture instead of a comb. Moreover, looking at he scan of Harry we can see a big inconvenience for us: only the outer surface and the sections at the breaks were captured. Moreover, the cracked surface texture was not captured, because we got the file only in a mesh file.

Therefore, it would be expected that this problem would not be so apparent in CT-scans. This technique captures the sections of the object, instead of making an interpretation of surface. Just then these sections are interpreted into 3D files. However, the precision of 0,3 mm proved to be insufficient for the artifact we chose:

As seen, the result was a more consistent file, which could actually be printed. Nevertheless, it was far from what we would call sufficient. Expecting this, we also made micro-CT scans of the object. The sneak-peaks of the object in the lab itself looked very promising. Yet our and publicly available computers could not handle the size of the data set (over 2000 sections!) and could only give results in the lowest resolution, leaving us with the following model:

As seen in the picture, the separate teeth are clearly visible, although the main body is missing. This can be easily solved if the used computer has 16GB RAM, since we could get a proper model in Avizo a few moments before it crashed due to memory insufficiency.

To conclude, only the micro-CT scanner offered the sufficient results for the compared artifact. The Artec Spider is very interesting if surface detailing in necessary or if textures/colors have to be captured. However, if not enough scans are made and combined, you will get an object lacking details, thus resulting in incredible amount of work hours in post-processing. Another solution for this would be to make CT-scans and combine them with the Artec Spider scans only for the details.

Plaster prints, structural solutions and CNC-milling, by Kotryna Valečkaitė

This week we focused on production techniques, yet not all of them proved to be possible to produce. In the background we also finished up processing all of the CT scans, of which an overview article will follow next week.

To begin with, we made multiple 3D prints: plaster prints of all of the loose pieces and a tryout of structural solutions in Ultimaker2. The first one we decided to translate into a game during the science fair, while the second one was primarily made for the mid-project presentation. Moreover, we made a form with a CNC milling machine which was later used for vacuum forming. This proved to be the cheapest, easiest and the most user friendly object so far.

Plaster print

Structural solution
 
CNC milling and vacuum forming
  

Secondly, we discarded paper printing as a possibility due to two main reasons:

1. Our files were too large to be opened in multiple programs with which we could have given the surfaces color;
2. The delivery times were too long

This led us to choosing another form which would work the best in the Connex printer. Yet that would lead to rather large expenses, exceeding 100 euros per object. What is more, using soft materials would mean that we strive more for a visual than a functional prototype, since the objects could not withstand warm drinks or even a dishwasher. However, some of this could also be achieved by simply printing the different materials apart in the Ultimaker2. Simply put, we are still struggling to determine what fidelity level we are looking for and what each prototype can achieve. Moreover, instead of having a single idea to work out we actually multiple interpretations of the same object:

1. Cheap, everyday object (vacuum form)
2. Object focusing on the aesthetics of historical footprint/3D printing (Connex prints/plastic injection molding)
3. A game, interactive cup (plaster print of shards)

In other words, it means that the objects form their own trajectories and cannot be easily compared with each other.

To conclude, we now have to focus on what precisely we want to achieve in these trajectories and how to do it using rapid prototyping techniques. That is not what we planned during the first week, but that will lead to more evenly divided workflow and, hopefully, more interesting results.

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.

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



To be continued…

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.

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: '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 19^e 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!)

OZV7-17-61

OZV7-17-61

OZV7-17-61

OZV7-17-163

OZV7-17-163

OZV7-17-163

OZV7-17-163

OZV7-17-18

OZV7-17-18

OZV7-17-18

Presentatie ScienceFair Technische Universiteit Delft

Hierbij een impressie van de presentatie van der eerste resultaten van het project tijdens de ScienceFair op de technische Universiteit Delft.

Uitnodiging: Science Fair TU Delft

Het maken en breken van alledaagse gebruiksvoorwerpen is van alle tijden. Omdat vroeger de waarde van deze objecten hoger was dan die van arbeid, werden ze meestal gerepareerd. In dit project worden alledaagse gebruiksvoorwerpen uit het verleden met behulp van CT-scanners in kaart gebracht, om vervolgens een 3D-reconstructie te maken. Hierdoor kunnen we erfgoed weer tot leven brengen als gebruiksgoederen in de huidige tijd. Dit project is een ontmoeting van ontwerp met technologie en erfgoed door een samenwerking met het Bureau Monumenten en Archeologie Amsterdam en Studio Maaike Roozenburg.

http://smartreplica2015.weblog.tudelft.nl

Tentoonstelling minor Advanced Prototyping
Dinsdag 27 oktober 2015, 12:30-15:00 uur
De afsluitende lezing van Nadya Peek begint om 15:15 uur
Locatie: "De tribune", Centrale hal, Faculteit Industrieel Ontwerpen, TU Delft
Landbergstraat 15, 2628 CE Delft