Paintings are not unlike sculptures, paint as a material has a huge impact on the way a painting looks. By illuminating a painting with light, it automatically gives highlights and shadows that form the way we see it. This is especially the case in the of late Rembrandt paintings and Van Gogh. This fact is often overlooked or not fully appreciated. In order to capture this topography convincingly, we needed to capture it in a very high resolution, which is already a problem for most 3-D scanners. Furthermore, the topography of the paint is very small compared to the size of the canvas and we want to capture color at the same time as we capture depth. This depth data is relevant for conservators and restorers (think of status-reports or analytical information about the craquela) and could in principle be used for exploitation using the museum shops (note that we as a university do not pursue this).
[caption id="attachment_2662" align="aligncenter" width="300"] Explanation of our method from the Sunday Times[/caption]
Therefore we devised a 3-D imaging method based on commercially available camera’s. We designed it such that it was dependent on the camera’s pixel count, so that by using 40 megapixel camera’s, we can capture large area’s at once with a very large accuracy. The camera’s were setup in stereo, and used triangulation in the exact way that our human eye does it. We also used a projector to project fringes to aid this triangulation. This yields an enormous depth map at the same time as we capture color. The scan of the Rembrandt’s Jewish Bride at the Rijksmuseum contains a billion points, all labeled with color information. In order to visualize this, we cannot use our computer screen (a billion points is more than 500x the amount of points a Full-HD screen can display. The logical step is then to print it. This was done by Oce (Canon Group) using their ‘state-of-the-art’ Fine Art 3-D printer that prints a depiction as large as the Jewish bride with a resolution of 50 microns in a few hours.
Although such a print might fool the regular observer, anyone with knowledge of paintings will immediately see that this is not painted with a brush. (Anyone with a microscope will see its drops painted mechanically with a nozzle.) If you consider such a print light-years ahead of a common poster reproduction, it is still light-years away from the original. We noticed that things like glossiness and transparency that are in each painting are very distinguishing in the original, and we are not yet able to reproduce. We are now working on further research in trying to model these facts as well. The goal of making such accurate reproductions, and comparing them with the original, is that we learn to understand exactly what we are looking at, and why it looks the way it does. What we learned so far is that there are many more elements that make the painting look the way it does, a part from the color and topography, that have an importance that we did not anticipate.
The scanning equipment is actually very straightforward, and only consists out of these parts. The rest of the parts is just cables and stuff to make the camera move in X and Y.
[caption id="attachment_2627" align="aligncenter" width="300"] Scanning the Jewish Bride at the Rijksmuseum[/caption]
||Nikon 80mm PC-E scheimpflug & polarisation filters
||Picoprojector fitted with a crossed polarisation filter
Real all about our scanning method in my thesis: http://repository.tudelft.nl/search/ir/?q=zaman
We used a hybrid system using stereo vision (2 camera’s) and fringe projection (using a projector). This system gives us unrivaled detail and capture speed, capturing 40 million points per capture, each point in 3-D space (XYZ) and in full color (RGB). Multiple captures allows us to capture the Jewish Bride for instance, a work that spans 160×120 cm; giving us more than a billion XYZ/RGB points. This is all done with proprietary camera’s that anyone can buy off-the shelf.
Printer and 3D printing technology (c) 2013 Océ (Canon Group)
. I was not directly involved in the development of the printer or the 3D pritning process. Nor did i push any buttons on the printer. The whole data-to-print part was all done by Océ.
3D Printing Technology by High Resolution Océ 3-D Fine Art Reproductions (more PR material at http://files.oce.com/video/hr3d.html
). Printer by and with 3-D printing technology from Océ. Video (c) Océ, and if shown, should be shown in entirety including proper attributions including the Océ trademark.
For all images, see this link: https://www.dropbox.com/sh/90n5pectl08yk39/MJ_2oZtQqz
Thanks to our museum partners:
Mauritshuis, Kröller-Müller Museum, Rijksmuseum.
And our technical partners:
Delft University of Technology and Océ.
[caption id="attachment_2651" align="aligncenter" width="300"] Exhibited the reproductions at TEDx Delft 2013[/caption]