The 3D model can be seen on sketchfab: https://skfb.ly/6QQHz
the 3D model
Textures
I thought a lot about how to texture the reconstructions and making them look good, while also making it clear, that they were reconstructions. My solution is displaying a wireframe over my reconstructions with textures.
For this to work, I copied and pasted both my coffin lid and box. I renamed these copies and after selecting all faces, I went to Face –> Wireframe and chose the settings: Thickness= 0.002, Offset= 0.001, Boundary and Replace are checked.
I then gave these wireframes a new material (blue with slight emission) in the shading workspaces to contrast the textures of the “normal” reconstructions (Image 1).
The “normal” reconstructions I textured with the stencil method (https://www.youtube.com/watch?v=lO8qDNZf5o0) I first unwrapped the coffin lid and box (and made sure to check the scale beforehand) then went over to the texture paint workspace and used wood and plaster textures (from https://texture.ninja/ and https://www.textures.com/). I used these textures as stencils to paint them on to my reconstructions. I used the straight ends of the stencils as borders, so I could show the build if the model (Image 2). To achieve this, I deletes a small part of the model, which at the end shows just the wireframe, another small part, shows the base color white, so a untextured model, and then I added the wooden plank structure for the box and one side of the lid. On the other side of the lid, I added the plaster texture, to show the coloring, that the original coffin lid part at the top of the coffin has. This way, the textures show how the coffin could have looked, and also the modelling of the coffin as a 3D reconstruction (Image 3).
Reconstruction of the coffin box
For the reconstruction of the coffin box I used the same file and collection as the coffin lid. I added a new cube in object mode ((Add –> Mesh –> Cube), and changed the dimensions of this cube again (x= 0.54 m, y= 1.90 m , z= 0.25 m). For the bottom I once again used my 0.3 m cube and scaled the coffin box in edit mode. I the added four loop cuts (from the toolbar on the left hand side) and moved them with the shortcut G-G. I then scaled these edges along the X axis (Image 1). After selecting all, I subdivided the coffin box four times. Then, from top view and in wireframe shading and being able to see the model of the original coffin lid, I selected the edges and scaled the along the X axis to fit the head form of the top part of the coffin (Image 2). I then selected the second row of edges at the top part to move the slightly, to create a thick edge for the coffin, before extruding selected faces inside of the coffin to create a 3D coffin box. Because the inset extrusion created faces that didn’t correspond to the outside faces, I used the loop cut tool and added non loop cuts to the inner part of the box (Image 3). While using the original coffin part and the reconstructed coffin lid, I used the knife tool in wireframe shading on the coffin lid, to create edges and faces so I could inset the faces and create holes for the fasteners to fit in. Here I once again after creating the faces, selected all four, to move all the same time, inset the slightly, extruded the into the model, then scaled them on the X axis while remembering to select Individual Origins for the Transform Pivot Point. Now both the coffin lid and the coffin box are reconstructed (Image 4).
Sources used to reconstruct the coffin:
Taylor, John H. 2009 ‘Coffins as evidence for a north-south divide in the 22nd – 25th dynasties’. In: Broekman, Gerard P. F., Demarée, R. J. and Kaper, Olaf E. (edd.) The Libyan Period in Egypt. Historical and cultural studies into the 21st – 24th dynasties: Proceedings of a conference at Leiden University, 25–27 October 2007, pp.375-415
Elias, Jonathan P. and Lupton, Carter 2018 ‘Regional identification of Late Period coffins from Northern Upper Egypt’. In: Strudwick, Helen and Dawson, Julie (edd.) Ancient Egyptian Coffins. Past–Present–Future, pp.175-184. Havertown/Oxford: Oxbow Books
Petrie, William M., Brunton, Guy and Murray, M. A. 1923 ‘Lahun II.’ Publications of the Egyptian Research Account and British School of Archaeology in Egypt 33. London: British School of Archaeology in Egypt
Taylor, John H. 2010 ‘Changes in the Afterlife’. In: Wendrich, Willeke (ed.) Egyptian Archaeology, pp.220-240. Chichester: Wiley-Blackwell
Reconstruction of the coffin lid
I once again copied this cleaned 3D model and opened a new general file. I started a new collection on the right hand side, by right clicking and pasting the 3D model. I also started a new collection for the reconstruction of the coffin and moved the existing cube into it and renamed it coffin lid. Because I had already decided the measurements of the coffin by going through literature, I changed the dimensions of this cube to the ones I wanted (x= 0.52 m, y= 1.27 m , z= 0.05 m). Because the coffin itself tapers at the bottom I added another cube (Add –> Mesh –> Cube), changed the dimensions (0.3 m) and used this to change the bottom of the lid by scaling the vertices in edit mode to the dimensions of the cube while in top view (Image 1). Next I subdivided the coffin lid four times, with right click –> Subdivide. For more cuts in specific areas I used the Knife Tool, shortcut K, and went from one vertex to the next, where I wanted an edge. I then selected on the bottom part al the faces I wanted to inset, the used the Extrude Tool in the Toolbar on the left hand side, and used it to extrude the region back inside the rest of the mesh (Image 2). Because the front of the coffin lid on the bottom is also inset into the rest of the lid, I selected the faces and vertices separately and moved them. Because the part of the lid in the original model has a slight curve, I selected faces on the top area, turned on Proportional Editing (shortcut O) and moved the right part of the coffin with G along the Z axis (Image 3). Afterwards I selected the whole bottom part in wireframe shading and scaled it in the Z axis to 0 so the bottom is straight again. To reconstruct the wooden fasteners of the coffin, I used the knife again and cut edges into the faces, where I wanted the fasteners to extrude from. I selected the resulting faces, inset them slightly and the extruded them, both sides at the same time. Because they taper at the end, I used the selected faces and scaled them. I learned the hard way to not just scale them, but first select Individual Origins as the Transform Pivot Point at the top of the workspaces. This way both selected faces could be scaled at the same time, but scaled individually (Image 4).
Cleaning the SfM model
After importing, rotating and scaling the model, I copied it to a new file to work with it further, while saving the model in the old file. To make sure to not change the model in any way, after pressing N and selecting the 3D object, I clicked the lock symbols next to the scale.
First step in cleaning the model is changing from object mode to edit mode. This can be done by changing the mode button in the top left corner or using the shortcut Tab. Now the object will be displayed by showing all the vertices. This can be changed next to the mode button to see either vertices, edges or faces (Image 1). For cleaning the model I found it to be the easiest with the vertex select setting. To get rid of the big areas of vertices, which can be deleted without destroying the object, I chose box select on the top part of the toolbar on the lefthand side or by pressing W. To be able to select all vertices, I sometimes changed the shading to wireframe but most of the time I used viewport shading but also clicked the x-Ray button. This makes selecting and deleting faster, but also lets you make more mistakes, because sometimes I selected and deleted parts of the model, I should not delete. So careful with the x-Ray toggle! I used the top view (Z or Numpad7), selected areas that could be deleted, which then show up in yellow (Image 2), so I could check if I didn’t select to much again… To delete the vertices, I first went to Mesh –> Delete –> Vertices and then used shortcut X. I repeated the process, in important areas, I used the lasso select. On thing that helped, was selecting the areas from inside the model. This way I could use the x-Ray and not select everything on the other side and delete those parts accidentally. But even so, I always checked the model for holes! (Image 3)
At the end I selected all (shortcut A or Select –> All) then went to Mesh –> Clean Up –> Delete Loose, to clean up my model and delete unnecessary vertices, edges and faces (Image 4). And as always: Save!
Importing 3D SfM models to Blender
The assignment for the paper is to build a reconstruction of an Egyptian coffin. We were given photographs of an existing coffin lid part. I have already build a 3D model with the photographs using Structure from Motion with Agisoft Software.
The first step to building a 3D reconstruction was importing this SfM model to Blender.
When opening Blender, I started with a General New File, this brings you to the default screen. There will be a cube, a camera and a light already visible. The cube will disturb the scene when importing an object, but because I learned that it’s important later, I now just hide it by clicking on the eye symbol next to it. I then went to File –> Import –> Wavefront (.obj) (Image 1). Or if you have a different file format, choose the one you want to import. I selected my file and thus the object showed on my screen.
My 3D object wasn’t centered, so I right clicked –> Set Origin –> Geometry to Origin. To easily rotate the object, I seleced it, pressed the rotate button on the left toolbar (Image 2) or after a while used the shortcut R. With the shortcut R, when afterwards pressing X, Y or Z, it will rotate only on that chosen axis. This makes rotating easier and faster.
The last step was scaling. This is only possible if you either now the dimension or the SfM model has a visible scale you can use. For this to work, I needed to change the shading of the model. By clicking the third or second to last circle (radio button) on the top left workspace in Blender it changes the shading of the object. Now the texture of the 3D model can be seen. I now unhid the cube from the beginning and scaled the cube to the measurement I could see on the 3D object (10 cm). The easiest way to scale the cube is pressing N or clicking the small arrow on the righthand side to show the Sidebar (Image 3). There I wrote 0.1 m into the Dimensions field at the bottom. To move the cube I pressed G and once again X, Y or Z for the axis I wanted to move on. To scale the SfM model, I first pressed the scale button on the lefthand side and then learned the shortcut S. As with the rotate or move shortcut, it is again possible to follow pressing S with X, Y or Z to scale on that specific axis. It is also helpful to change the view for scaling: I change between pressing either on the blue, red, green coordinate system and clicking on either X, Y or Z or using the shortcuts: Numpad1 (x), Numpad3 (y), Numpadz (z).
After scaling the model, it is important in the long run to apply the new scale (only works in object mode). I went to Object –> Apply –> Scale (or press Ctrl-A or Cmd-A and Scale) (Image 4). And of course: Save!
why I started this blog:
this blog is part of a term paper and will hopefully help documenting the steps it takes to reconstruct an Egyptian coffin, the goal will be a complete 3D model, which will be posted at the end of the reconstruction phase
archaeological reconstruction with blender 