[CASE STUDY] 3D Scanning of Original Masks

In this article, we will talk about how we digitized original masks for the Art of the Mask virtual exhibition, what equipment was used, what difficulties arose, and how they were solved.

 

About the project

The Art of the Mask exhibition is a project that was opened in the virtual space within the framework of the annual Krasnoyarsk Book Culture Fair (KRYAKK) under the auspices of the Mikhail Prokhorov Foundation.

 

The description of the event says: “The mask is one of the most mysterious cultural phenomena and an immensely appealing garment, partly due to its playful potential. Dealing predominantly with the upper half of a face, a mask comes into play with identity, making it invariably attractive for experimentation among artists and designers."

The website of the Art of the Mask virtual exhibition

A model obtained as a result of scanning used on the site

34 works made of a variety of materials and in very diverse techniques were collected and scanned for the Art of the Mask online exhibition. The project suggests a unique experience of immersion in a special environment where user interaction with 3D models is accompanied by atmospheric music.

   

Task

Oceania mask page on the Art of the Mask virtual exhibition website

The organizers of the exhibition turned to us with an unusual order. According to their idea, the concept of the website dedicated to the exhibition should include not just images of masks but 3D models. Only in this case can the user get fully acquainted with the unique works: turn them around, examine from different angles, zoom in and look at the details, or, conversely, take a look at the general view of a mask.

Oceania mask by Dmitry Shabalin before 3D scanning

According to the client, this project was unique. The organizers were not faced with such tasks before, since all exhibitions were held in person. Due to the pandemic and the closure of exhibition spaces, it was decided to transfer the event to an online format. At the same time, it was important to preserve the sense of 360° view of exhibits, like during a personal presence at the event. The customer had the choice: either to shoot 360° videos or prepare 3D models — the latter option seemed more difficult but more effective.

In technical terms, the customer needed 3D models with textures and materials, as well as the ability to upload them to a special online server for viewing 3D objects so the user could view a detailed three-dimensional model in real time and without installing special software.

At first, the Top 3D Shop specialists planned to model most of the provided masks, expecting to use 3D scanning only for the most complex objects in terms of geometry.

However, the capabilities of the existing equipment made it possible to obtain about 80% of the geometry using only scanning, and this was enough to create the final 3D models.

  

Problems

Red Pixel mask by Anastasia Alekhina

At the very start of the project, arose a few difficulties. One of them was tight deadlines. The masks were coming in batches from several cities. The first batch of ten masks, for example, was given for one week. During this time, it was necessary to make good scans of all the objects, bring them to the highest quality result, and upload them to the platform for viewing models.

According to the customer, many companies providing such services refused to cooperate because of the complexity and deadlines.

An even greater difficulty lay in the masks themselves. Some of them were extremely movable — their geometry changed with the slightest tilt or turn on the mannequin. The structure of others had very deep hollows. Some of the masks consisted almost entirely of transparent glass, some were black, and some were even specular.

Soul Reflection by Kristina Golets

More than that, during the scanning process, it is needed to capture not only the geometry but also the texture as close as possible to the original. And this is not easy, considering the number of variables that must match: color rendering, incident light, light reflection from the material, brightness, contrast. It is necessary to take into account that colors (and light) on the original and the computer screen are perceived differently. Finally, colors can look completely different when the 3D model is shown online when rendered by the server in real time.

   

Process and equipment

Mohawk mask by Vanya Tonic

In the process of 3D scanning of the masks (34 copies in total), the Top 3D Shop service department specialists used two scanners: EinScan Pro 2X Plus and EinScan Pro HD by Shining 3D.

Shining 3D EinScan Pro 2X Plus 3D scanner

Shining 3D EinScan Pro HD 3D scanner

From the very beginning, it was planned to use the EinScan Pro 2X Plus to work on the project. This 3D scanner has long established itself as a high-precision tool for the manual digitization of objects of different dimensions and with different levels of geometry complexity. You can find out more about the device from the EinScan Pro 2X Plus review.

In the case of masks, manual scanning was the only option for implementing the project due to the difficulties described above.

In addition to the EinScan Pro 2X Plus, a color camera was also used. It is an add-on that captures the texture of an object with high accuracy and allows you to create a most realistic digital model. Read about this module in the review of add-ons for Shining 3D scanners.

Color camera for Shining 3D EinScan Pro 3D scanners

A little later, the specialists of the service department had the opportunity to test the new generation of Shining 3D hand-held scanners — EinScan Pro HD. The new product surpasses the previous generation devices in many respects. The Pro HD has higher accuracy, resolution, and scanning speed. The key factor after which the specialists completely switched to using the new scanner was the excellent capability of scanning dark and black objects. The EinScan Pro HD review tells more about this device.

Some details could not be scanned under any circumstances — the mirror on one of the masks and mesh surfaces. But the geometry that the scanner was able to "catch" was quite enough for the subsequent manual modeling.

  

Preparation of final 3D models

After we are done with 3D scanning, it is time to process finished scans. Here belongs cleaning, linking, filling holes in the polygonal mesh, adjusting the brightness and contrast of the texture in the scanner software, and finally simplifying and optimizing the texture for the server. Below we will talk about this process in more detail.

After scanning, we get a point cloud. In our case, the point cloud and the texture of the object itself. This is how a completely scanned object looks like.

Then we select the model resolution between three difficulty levels (the number of polygons). At this stage, it is advisable to understand what model is needed as a result and whether the geometry will allow it to be uploaded in low poly. So, if there are many small details on the model, it is worth considering if these details will be necessary for the result.

We chose a high poly model to simplify it later. In our case, the density of points and the ratio of speed to quality do not play a significant role, but in other projects, adjusting these parameters can speed up processing or improve the quality of a model.

Now we go directly to editing the polygonal mesh by clicking the Mesh Model button.

We have the choice of a filled or unfilled model (Watertight and Unwatertight). In the first case, all holes are filled (including those from the marks, if any) — even large ones that do not need to be filled. This method is suitable for completely (or almost completely) closed scans, which the program cannot distort during processing.

If there were large gaps in the scan or it is necessary to eliminate the program's interference with the geometry, which is crucial when scanning objects for reverse engineering, then the Watertight method will not work.

In our case, this option is not suitable since the scans are not closed, the masks don't have a back wall and it is not required for the final project. Besides, the Watertight algorithm narrows large gaps too coarsely.

Therefore, we choose the second option — it does not allow stitches, does not fill the mark holes or change the geometry.

Mesh transformation begins. This stage can take from a few seconds to tens of minutes (in our case, about 15 minutes), depending on the size of a project, the amount of RAM, and the performance of the computer.

If you run the program on a computer with low performance or a small amount of RAM, be prepared for the hours-long process and possible processing failures.

If you are not certain about the performance of your computer, be sure to save your scan project. In any case, it is still better to keep a copy. Otherwise, you can lose not only time but the project itself.

The mesh being processed, small tears remain. They are not striking; still, they should be processed as well. In the Manual Hole Filling window, we select one of the three algorithms and start the process. In most cases, it is recommended to use the Tangent type — this filling of holes does not lead to the formation of bulges above the main plane, even if it's curved. The other two options — Flat and Curvature — are suitable for flat or curved surfaces respectively.

It is possible to automatically fill all the holes with the selected type, or you can manually choose a certain section — the selected holes will be highlighted in green. At the end of the filling, proceed to edit the texture. 

There are not many texture adjustment options in the Shining 3D software — just brightness and contrast. The color correction will have to be done in a third-party program, after uploading the texture.

Upon adjusting the brightness and contrast, we move on to simplifying the geometry. This procedure reduces the size of a final model in megabytes but will also remove small details. It is important to choose the appropriate simplification settings so as not to lose the necessary detailing.

Before saving, the program shows the final size of a model in different formats. We chose OBJ: unlike STL, it allows "tightening" the texture of a model. 

Now it is time for the final stage, Texture Remapping, which involves rendering or the preparation of a texture map. After scanning, we get a very raw and scattered texture impossible to work with manually. See the examples below.

At this stage, in addition to the actual remapping, gaps and texture inaccuracies are eliminated. In fact, you can do without remapping — just remove errors in the texture. But after that, you will not be able to work with the texture manually.

If you tick the Texture Optimization box, then, in addition to fixing errors, remapping will also be carried out. This increases the processing time but eliminates the need to return to this stage (it is impossible to implement this stage outside the project since the connection between the scan, texture images and mesh gets lost).

The process of remapping with regular retopology takes about 3 minutes

To avoid losing your changes and edits, be sure to repeatedly save the project. After completing the processes described above, you can work with the model texture separately and then upload the result to the site.

Texture without optimization (retopology)

Texture after optimization

Handmade texture made by a 3D modeler from scratch (for comparison)

Wind of Change mask by Ulyana Polyanicheva, draft 3D model

Wind of Change mask by Ulyana Polyanicheva, the final 3D model

On the server itself (the client proposed using the existing account for the storage and demonstration of 3D models SketchFab), the light, rotation restrictions, material properties, and rendering camera settings were adjusted.

3D models of masks on the SketchFab website

The total amount of data was about 200 gigabytes and included the point cloud sources, textures with materials, and ready-made 3D models.

   

Conclusion

Initially, it was assumed that 3D scanners would not capture all the geometry and, most likely, only partially cope with transparent, shiny, and black textures. But it turned out that with the proper approach it is possible to scan both the texture and geometry of such objects by applying a very thin layer of matting spray. This concerns specular and transparent textures. The power and brightness of the lighting built into the scanners were enough to capture black surfaces as well.

The client was satisfied with the work performed and the completion date. It should be noted that the complexity of the design of some of the masks was so high that it made sense to resort to 3D modeling from scratch when creating their digital copies.

In terms of reliability and accuracy of the equipment used, both the EinScan Pro 2X Plus and EinScan Pro HD by Shining 3D performed very well. The newest Pro HD 3D scanner demonstrated in practice all the changes announced by the manufacturer that differentiate this device from the previous generation — higher accuracy, resolution, and scanning speed, as well as an improved ability to scan objects of dark or black colors.

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