2D to 3D

By Chelsea Kim

As an intern working with the conservation department, I have received the opportunity to work on many projects and experience things I never thought I would. Recently I have been working on this software called Reality Capture using photogrammetry. Photogrammetry is a process that uses an abundance of photographs to create a 3D model without any distortion from many overlapping images stitched together to form a detailed and geometrically corrected image called an orthomosaic. This process is usually used on larger objects, and this is because it’s too big to be in frame when taking pictures and has a lower quality with distortion which is far from perfect, and Christy Ching explains more in depth about this in her previous blog post.

I want to show how to create a digital three-dimensional model using the software, Reality Capture, and I’ll demonstrate with an example of the after-treatment photos of an Egyptian coffin.

To start off with, having pictures of the object is a must. For this example, they were already taken and edited in Photoshop, to adjust the white balance using adobe bridge ahead of time. Then I begin by opening the software and then under workflow at the top left corner, I select “inputs.”

Screenshot of the software highlighting where to click “Inputs” which is above “1. Add Imagery”

Then I select all the images making sure that they were a .jpeg file and then I click on “Align Images” as highlighted above. After the images are aligned, a transparent box surrounding the coffin appears. I adjust the box by dragging the control points around to make it as small as possible without cutting off any part of the coffin. As you can see in the image below, using E883C, the box is close to the coffin but does not intercept the coffin itself.

Screenshot of the Egyptian coffin E883C after the images were aligned with the transparent box adjusted to tightly around it.

Now for the fun part to see the coffin take shape, I click next to “Calculate Model” to select “Preview Quality” as highlighted below. Then I go to the tools bar to use the lasso option to erase all the unnecessary space around the coffin. Then after being satisfied with selected area, I click on “Filter Selection,” which turns the selected areas from orange to dark blue showing that it worked.

Screenshot of the coffin after selecting “Preview Quality.”

Finally, I go back to the Workflow bar to select “Texture” which is highlighted below and then it shows all the details of the 3D model without any distortion in high detail and quality.

Screenshot of the 3D model after being textured.

Progress update on the stola coffin treatment

For the past few weeks, it has been full steam ahead on the treatment of the stola coffin lid. The lid is made of smaller pieces of wood joined together, then covered generously in areas with a thick layer of coarse mud plaster, followed by a thin layer of a finer mud plaster, followed by paint and a varnish. There are also raised details that were built up with gesso before painting.

This large piece of painted mud plaster (detached from the foot of the coffin, seeing on the left) is 11 cm thick.

This large piece of painted mud plaster (detached from the foot of the coffin, seen on the left) is 11 cm thick.

This area of damage clearly shows the wood substrate (green arrow), coarse mud plaster (blue arrow), and finer mud plaster (red arrow).

This area of damage clearly shows the wood substrate (green arrow), coarse mud plaster (blue arrow), and finer mud plaster (red arrow).

The two major condition problems on the coffin are found in the mud plaster layers: the coarse mud plaster has lost cohesion and in many places has separated from the wood below, and the finer mud plaster has also lost cohesion, so much so that it has deteriorated to a fine powder in places. I have spent over 150 hours so far readhering detached plaster, consolidating the powdery plaster, and realigning and stabilizing loose fragments on the coffin. Today I’m posting a few before and after treatment details to show the progress.

Here are before and after details of the top of the head showing an area where I had to readhere some large fragments of painted plaster:

Top of the head before (left), during (center), and after (right) reattaching painted plaster fragments

Top of the head before (left), during (center), and after (right) reattaching painted plaster fragments

Here are before and after details of the left eye showing the consolidation of exposed powdery mud plaster:

Detail of losses near the left eye before, showing powdery mud plaster (left) and after cleaning and consolidation of the mud plaster in the losses

Detail of losses near the left eye before, showing powdery mud plaster (left) and after cleaning and consolidation of the mud plaster in the losses (right)

And here is an area on the side of the head where I found that some fragments were previously attached in incorrect places. They were repaired long ago (with no documentation) with an adhesive that is soluble in warm water. I reversed the old repairs and found the correct locations for the fragments. I’ve outlined the fragments in their incorrect locations in the before treatment image on the right, below:

Detail of treatment on the side of the head before, with misplaced fragments outlined in pink (left), and after respositioning (right)

Detail of treatment on the side of the head before, with misplaced fragments outlined in pink (left), and after respositioning (right)

I still have lots of work to do before the treatment is complete, but I’m making good progress! I hope to be finished with the treatment early in the new year.

Observations of a stola coffin lid

As if there is not enough up here (see our recent post about the Egyptian storage move and associated conservation work), this week we brought another quite large object into the lab, and it might be my new favorite object up here.

The lid of our yellow stola coffin

The lid of our* yellow stola coffin

This is the lid that belongs to the late 21st/22nd Dynasty yellow coffin base which we recently treated here in the Artifact Lab. Due to its previous location in storage, I hadn’t been able to take a close look at it until this week. Now that I’ve gotten to spend a few days with the lid, I’ll tell you that it’s total eye candy. If you were impressed by the painted decoration on the base, the lid will give you even more to get excited about.

I only just started to examine and document the lid and I will continue to update the blog as I work on this object, so today I’m just going to mention a few things about it, and some of my favorite details so far.

First of all, you may have noticed that I referred to this as a “stola” coffin in the image caption above. The term “stola” refers to the narrow red band depicted on the coffin that encircles the neck and crosses over the chest and over the oversize collar. Both the presence of the stola and the oversize collar have been recognized as distinctive of the late 21st/early 22nd Dynasty (see other examples and explanations here and here, and special thanks to Dr. Kara Cooney at UCLA for information as well).

The figure depicted on this coffin used to have a beard, which is now missing, but there is a hole in the chin indicating that it was once there.

Detail of the hole in the chin

Detail of the hole in the chin

The arms are depicted as being crossed over the chest and the hands are made of separate pieces of wood. The hands on this coffin are clenched and I have read that this is reserved for male coffins while females are depicted with hands open and lying on their chests. I’m assuming the fisted hands mean that this coffin belonged to a man, but I’ll have to check with our Egyptologists to confirm, since I cannot translate any of the text myself. I also really like the fact that the thumbnails are painted in:

Detail of the left hand

Detail of the left hand and thumb

What else can I say about it? Well, it is beautifully painted and also varnished just like the base with a yellow-colored pistacia resin. This pistacia resin causes many of the areas painted blue to appear green:

Much of the blue lines on the wig appear green, but in areas where there is no varnish, you can see the blue color of the paint.

Many of the lines on the wig appear green, but in areas where there is no varnish you can see the blue color of the paint.

There is a thick layer of dust on the surface of the coffin, but I can tell it’s going to clean up well. Check out the embossed details in this raking light image, which were built up with gesso:

Detail of the embossed designs on the central part of the lid

Detail of the embossed designs on the central part of the lid

This is going to be a fun object to work on! I’m looking forward to getting started with the treatment.

* I should clarify that this coffin technically belongs to the Philadelphia Museum of Art (PMA) but has been on long-term loan to us for nearly a century. We received this coffin as part of an exchange of objects between our 2 institutions in the 1930s. I am carrying out the treatment in close consultation with the conservators at the PMA.

The treatment of (half of) a yellow coffin

This week, we finally finished the treatment of the lower half of our 21st/early 22nd Dynasty yellow coffin.

A view of the interior of the coffin before (left) and after (right) conservation treatment.

A view of the interior of the coffin before (left) and after (right) conservation treatment.

The treatment mostly involved cleaning the interior surfaces to remove dust using a soft brush and HEPA-filtered vacuum, and cosmetic sponges. Here’s another view to give you a better sense of just how much grime had accumulated in the interior of the coffin:

A detail of the head of the interior of the coffin before (left) and after (right) conservation treatment.

A detail of the head of the interior of the coffin before (left) and after (right) conservation treatment.

There was also a fair amount of flaking and lifting paint, which needed to be stabilized. We used 1-2% methylcellulose in 50:50 water/ethanol to consolidate flaking paint, and Japanese tissue paper and 5% methylcellulose to fill gaps.

In the course of the treatment, I have also continued to research the significance of the holes drilled into the bottom of the coffin, which can clearly be seen in the overall images at the top of this post, but here is another look:

An overall shot of the coffin bottom, with a detail of 4 of the holes below.

An overall shot of the coffin bottom, with a detail of 4 of the holes.

I’m anxious to start working on the lid of this coffin, which will inevitably provide more information about this object and it’s history. We should be able to bring the lid from storage up to the lab sometime this summer, and I’ll post images of it as soon as it arrives. In the meantime, I have enjoyed researching these types of coffins and finding images of similar ones in other collections (like this one at the Petrie Museum, this one at the Houston Museum of Natural Science, and this “remuddled” coffin at Stanford University) which is helping me gain a better understanding of these coffins and the contexts in which they were made.

Tawahibre, front and center

As promised, Tawahibre’s coffin lid is now on display, front and center, in the Artifact Lab.

Tawahibre's coffin lid on display at the entrance to the Artifact Lab

Tawahibre’s coffin lid on display at the entrance to the Artifact Lab

Getting this Late Period painted wooden coffin lid ready for display required months of treatment to clean the surface and to stabilize the flaking paint, powdery and crumbly gesso, and loose wood components. I blogged rather extensively about the treatment – follow this link to view some of my previous posts.

Here are some treatment images that were posted on the museum’s Facebook page last week, showing details of the head/upper body before, during, and after treatment:

E885CbeforeduringafterCome visit Tawahibre in the lab, where you can examine the coffin lid up-close, read the conservation treatment report (which includes some materials identification reports), see more before, during, and after treatment images, and discuss the treatment with the conservator during open window times.

 

I spy with my little eye…

Update – this post contains blurred images of human remains and outdated language. We no longer use the term “mummy” and instead use “mummified human individuals” to refer to Ancient Egyptian people whose bodies were preserved for the afterlife. To read more about these changes, follow this link.

A long time ago I posted an image of our Mummy Gallery, circa 1930s. Well, I find myself returning to this photograph again and again as I work on new objects in the lab.

The “Mummy Room” ca. 1935

Can you find two of the objects that we’re working on right now, the beautifully preserved painted wooden coffin and the shabti box and shabits, all from the New Kingdom? Here are images of these objects, just to help you out:

Overall view of the interior of the coffin from above
Overall view of the interior of the coffin from above
The shabti box and one of its associated shabtis
The shabti box and one of its associated shabtis

Did you find them? I’ll post the image of the mummy room below, with these objects circled in red.

And here is a cropped version of this image, to better show these objects:

While it’s just cool to see an image of these objects in a previous display, it’s also helpful to me as a conservator. I can see how they were mounted for exhibit (the coffin is standing upright, the shabtis are on little platforms) and I can also get a sense of condition at this time (for instance, the middle lid of the shabti box is missing in this image, and I can see some losses to the painted surface as well).

I’m am nearly finished working on the shabti box and shabtis, and the coffin will also be completed this year, so we will finally be able to put these objects back on exhibit.

Coming up next week, I will be posting some multispectral images of the shabti box and shabtis, which is helping us better understand the original colors and also to see some of the painted details, which are now largely obscured by the orange pistacia resin varnish.

Out with the old, in with the new

There are some new objects to see in the lab!

Just this week, we began returning some of our recently-treated objects to storage and exchanging them for some new stuff, including a painted wooden coffin (this is a photo of the coffin box without the lid – note the elaborate painted decoration on the interior):

coffina falcon coffin and “mummy” (I’m putting “mummy” in quotes here because this mummy looks like it’s a corn mummy, made by wrapping up a mixture of sand, grains, and plant fibers):

falconmummythese pieces of a painted wooden coffin board with two Wedjat eyes:

coffinboardand this ibis mummy, with exposed feathers!

ibismummyThere are some other things too, including some cartonnage and another animal mummy, which we’ll post photos of soon.

As always, these photos really don’t do these objects justice. You’ll have to come check them out in person! And we’re only just starting to examine them, so we’ll definitely post information as we learn more. If you have specific questions about any of these objects, please let us know!

 

Wood ID

I’m currently treating 7 fragments of a painted wooden coffin from Abydos. Lately, many of our visitors have been asking what kind of wood was used to make this coffin. This has actually been a question that we have been asking ourselves, and we are trying to see if we can come up with an answer.

In ancient Egypt, large timbers for coffin-making were scarce, so the wood was either imported from places like the Mediterranean, the Near East, or from other parts of Africa, or the Egyptians would cobble together smaller pieces of wood from local sources. Based on previous studies, we have a finite list of types of wood that are known to have been used, but from there we need to move to looking at the object itself.

These images show the exposed wood on the side (left) and back (right) of one of the coffin fragments. Can you guess what type of wood this might be?

These images show the exposed wood on the side (left) and back (right) of one of the coffin boards. Can you guess what type of wood this might be?

As conservators, we are educated not only in object treatment, but in the analysis of objects, and the examination of tiny fragments of objects, like plant and textile fibers, wood, and pigments. But many of us don’t do wood ID all that often, so it can take awhile to get set up, to re-orient ourselves to what we’re seeing in the samples, etc. AND it requires a sample, which we don’t often have access to. Fortunately, for me, I have some already detached samples from these boards and access to someone who does this type of work more frequently, archaeobotanist Dr. Naomi Miller, so I turned to her to help me with this work.

Dr. Miller looked at the samples I had and selected one that looked promising, due to the exposed cross-section on one end. I mounted this sample under our binocular microscope and took a photo, to help her study it further and compare to known reference samples.

E12505_woodID

The wood fragment with exposed cross section, 60X magnification

From this sample, Dr. Miller was able to determine that this is a hardwood, based on the presence of clearly visible rays and thick-walled pores, many of which are radially paired (pointed out below).

Slide4Based on these features and the known types of hardwoods used in ancient Egypt, this helped narrow down the likely possibilities to Common ash (Fraxinus excelsior L.), Carob (Ceratonia siliqua L.) and Acacia (Acacia sp.). Dr. Miller considered other types but ultimately excluded willow (Salix), oak (Quercus), elm (Ulmus) and sycamore fig (Ficus sycomorus) due to either the presence or absence of certain features.

In an attempt to further narrow down the possibilities, I cut thin sections from the sample that Dr. Miller examined, from the cross-section and tangential surfaces, and wet-mounted them on glass slides. Looking at these thin sections with our polarizing light microscope (PLM), I was able to see some of these features a bit more clearly.

Cross-section, 50X magnification

Cross-section, 50X magnification

In the cross-section above, the pores are visible as solitary or paired, and mostly uniseriate (1-cell wide) rays are visible. The tangential section also shows mostly uniseriate rays, but some bi-seriate rays are visible as well.

Tangential section, 50X magnification

Tangential section, 50X magnification

Cutting these sections from the wood sample, which was quite degraded, was difficult and unfortunately I’m not really able to pick out many other features from the sections that I examined. I will have to get Dr. Miller to weigh in on this again, but in the meantime, I’m going to go out on a limb and say that I’m leaning toward this wood being acacia. One thing I forgot to mention is that the wood of the coffin board fragments is a deep red-brown color. Acacia is known for being a red, hard, and durable wood, and while it produces small timbers, we know that it was used for coffin-making, among other things.

Fragmentary painted coffin from Abydos

If you are a member of the museum, you may have already seen some information about these painted coffin board fragments in the most recent issue of Expedition magazine:

E12505_2These fragments, which date to the Middle Kingdom (ca. 2000-1700 BCE), were excavated from the North Cemetery of Abydos in 1901 by John Garstang. The museum supported Garstang’s work through the Egypt Exploration Fund.

Despite the severe insect damage, the preservation of the painted details on these fragments is remarkable.

This fragment features 3 usekh collars, which were often reserved for nobility. Beside each collar is a mankhet, or counterpoise. The hieroglyphs above are the names of each of the collars, which are slightly different.

This fragment features 3 usekh collars, which were often reserved for nobility. Beside each collar is a mankhet, or counterpoise. The hieroglyphs above are the names of each of the collars, which are slightly different.

A detail of the usekh en nebti, the collar of the two mistresses that incorporates the uraeus and the vulture

A detail of the usekh en nebti, the collar of the two mistresses that incorporates the uraeus
and the vulture (7.5x magnification)

These coffin board fragments have never been exhibited, and our renewed interest in them is due to the fact that we are currently excavating tombs from the same time period in South Abydos, including the funerary complex of Senwosret III. You can read a lot more about this project in the recent Expedition issue and on the museum blog by following this link.

In order to exhibit the coffin fragments, they need some extensive conservation treatment. Their surfaces are dirty, the paint is cracked, cupped and lifting from the wood support, and is very fragile, and some of the boards are structurally unstable due to the extensive insect damage.

We are currently working on these boards in the lab, and we have made some good progress. We are cleaning the painted surfaces with a kneaded rubber eraser. The eraser can be shaped to a fine point, and working under the binocular microscope, it is possible to remove the dirt from most of the painted surface without disturbing the fragile paint.

We are using kneaded erasers (left) to clean the delicate painted surface of these coffin boards (right)

We are using kneaded erasers (left) to clean the delicate painted surface of these coffin boards (right)

Some areas of paint need to be stabilized before they can be cleaned. After testing a variety of adhesive solutions, I settled on my old friend methyl cellulose, a 2% solution of methyl cellulose in water to be exact, to consolidate fragile areas.

Paint consolidation is being carried out under the microscope with a fine brush

Paint consolidation is being carried out under the microscope with a fine brush

I am now working on testing some fill materials, both to stabilize the edges of lifting paint and also to stabilize the fragile wood. I will post an update as soon as I make some decisions and proceed with this part of the treatment!

 

Opening Tawahibre’s coffin

I don’t think many people will argue with me about this – a day at work (heck, a day in my life!) can’t really get more exciting than opening a 2500+ year old Egyptian coffin. For the last several months, we have been carrying out treatment to stabilize the loose wood, crumbling gesso, and flaking and powdery paint on the lid of Tawahibre’s coffin. While there is still a lot of aesthetic work to carry out, we finally got the lid to a point where we deemed it stable enough to remove it from it’s base.

Removing the lid from an incredibly fragile 2500+ year old coffin doesn't happen without a lot of planning and discussions ahead of time.

Removing the lid from an incredibly fragile 2500+ year old coffin doesn’t happen without a lot of planning and discussions ahead of time.

Okay, okay, so, the coffin has been opened before, and we knew that there wasn’t a mummy inside anymore (she’s down in storage), but opening the coffin was monumental nonetheless, as the lid hadn’t been removed in decades and we didn’t really know what we would find inside.

Fortunately, we were able to lift and move it without any problems:

DSC_0765DSC_0771DSC_0776(they really make it look like a breeze, don’t they?)

And now the lid is safely resting on a new palette, and the interior of the coffin is revealed to us for the first time:

Tawahibre lid and base separated

Yup, just another day in the Artifact Lab. We’ll fill you in later about what we’re learning and what’s going to happen next.