adrienlucca

CLICK ON THE PICTURES!

Rosace, quasicristal dodécagonal

baie-100

Variations of the visual appearance of a stained glass window during the course of the sun in the sky.

This slideshow requires JavaScript.

Le ciel, le soleil et un vitrail orienté Est

exemple-de-la-baie-0

[Document in French] A timeline of the visual appreance of a stained-glass, in parallel the colors of the Sunlight and the colors of the Sky, during a sunny summer day.

(PC : click-droit > “ouvrir l’image dans un nouvel onglet” pour voir l’image en grand)

(right-click > “open image in a new tab” to zoom)

Sunlight / Stained-glass

This slideshow requires JavaScript.

Simulation of the changing visual appearance of an East-oriented Stained-glass window depending on the daylight color and orientation:

7:30 AM: before the sun rises, the sky illuminates the window

7:45 AM: a yellow Sunlight reaches the window

8:00 AM: the Sunlight is already whiter

12:00 AM: the Sunlight is white

12:30 AM: the Sunlight disappears, only the sky illuminates the window

4:00 PM: idem

6:00 & 8:00 PM: the sky’s color changes slightly

All this has been simulated using physical data about the light of the Sun and the Sky in the south of France, and physical data acquired by scanning colored glass with a spectrophotometer.

 

14 steps of an algorithm

This slideshow requires JavaScript.

This gives you an idea of how I work. Every operation is the result of hundreds lines of code, but the logic is pretty simple. We have a quasiperiodic cristal made of triangles and we detect regular shapes (squares, diamonds, octogons, 6-gons, etc.). This creates a pattern that’s later gonna be made of little glass pieces.

Glass-light interactions on the prototype

window-detail

With the studio Debongnie (http://vitraux-debongnie.be), we are working on a Stained-Glass prototype to be installed in a 13th Century Cistercian Abbey in the south of France. My project passed the pre-selection and we are in the final of the competition against 2 other duos artist/glass-studio.

Cistercians didn’t put colors, pictures or crosses on their windows. Their windows were supposedly « albae fiant, et sine crucibus et pricturis » (white – or colorless(?) -, and without cross and representations). Very few original 12 & 13th Century Cistercian windows survived and we know little about how they interpreted this rule.

My proposal is to produce “white light” in the Abbey, by a combination of different optical types and colors: transparent light greenish blue, light blue and light reddish blue mostly, and opalescent whites that diffuse light and are less transparent.

*

This slideshow requires JavaScript.

 

METAMORPHOSIS

During the course of a sunny day, the light will vary. The visual appearance of the window will be changing a lot because of this variation.

Behind the window is a yellowish-white stone-wall. Before noon the window and the wall behind it are in the shadow. Around noon, the sun illuminates the window directly and the opal glass are becoming very bright. During the afternoon the wall behind becomes illuminated, allowing the transparent colors to appear. Finally around 4-5PM the shadow moves on the window and the opal glass stops being so bright.

*

This slideshow requires JavaScript.

GOLD + BLUE = WHITE LIGHT

Interestingly, opal glass will appear white but will project amber light on the walls or the floor of the building. The average color of the light passing through the window has been computed to be white. The glass selected last month in the factory Lamberts in Waldsassen were chosen to produce this effect, and the situation has been simulated with the light spectrum as measured last summer in the south of France.

couleur-avec-le-ciel-copy

BLUE SKY REVEALS THE COLORS

Finally, there’s the possibility of seeing the sky from an angle in the Abbey. When people will look at the window with the sky behind, it will reveal new colors again. What looked almost colorless will appear as different shades of blue and yellowish whites.

 

Picture of the first third of the window-prototype

premier-tiers

Finally, the glass version !

This is a stained glass element made with a traditional technique. The black lines are a combination of hand painted “grisaille” and lead.

I’ll soon describe the entire project in a longer post, stay tuned ;)

 

glass prototype making

This slideshow requires JavaScript.

Next week we’ll finally be able to judge the result.

Preview of prototype placed in-situ

in-situ-simulation

probably not accurate, but it gives a first idea.

The list of unique shapes

1469813462-5-csv_data_v12-npy_20_cols_new15_p-svg-npy_-svg

 

Each unique shape that makes the map from the previous post. Total 173 unique shapes, 299 glass pieces.

The map!

1469813462-5-csv_data_v12-npy_20_cols_new15_p-svg

the map of the stained-glass

This is really the result of intense work during 4 1/2 months. More news soon.

Printing the map

Simulation of “Opal” glass

opal-simulation-d65

Opal glass is a strange material. It is a colorless glass that scatters blue light in the same way the earth’s atmosphere does it with sunlight: the sky is blue because blue sunlight doesn’t travels straight in large thicknesses of air, but in every directions. The sun appears yellowish because of the same reason: the blue part of the sun’s light spectrum has partly vanished from its rays under the form of blue sky.

In the opal glass, a very thin layer of diffusive “milky” glass containing very tiny particles is plated (“plaqué”) on the glass. Opaque white “flashed-glass” and opal “flashed-glass” are exactly the same material, but on the opaque version the layer of milky glass is very thick, up to 1 mm, while it can be maybe a 100 times thinner on very light opal glass.

It is very difficult to simulate the color of this glass on the computer: on the light table you see nothing but what seems to be a “cloudy” or “hazed” white glass. You need some distance to see the color appear, you need the light rays to pass in straight lines through  the glass otherwise the color won’t appear.

I did some research and I arrived to some pretty good results. The numbers under the pictures indirectly refer to the thickness of the milky layer. The left color is the one that appears by light transmission, the right one by light scattering.

This slideshow requires JavaScript.

When the layer gets really thick, transmission becomes zero and the glass is opaque and white.

not-ordinarytransmission

It’s really “white” but the light passign through it becomes yellow-brown.

 

…working on a Stained-Glass prototype

IMG_0933.JPG

A paper model with “scanned” and calculated colors for the blue sky behind…

Below, the left one simulates a cloudy sky, the right one the blue sky

img_0932

This is the design made by something like 5000 lines of code in Python 2.7 ;)

_sun_1469813462-5-csv_data_v8-npy_17_cols_lim_4_ha_0

 

Serious glass sheet optical anatomy

g161

The first result of the algorithm

1im

A

1back

B

glass-spectrums

C

A & B & C : the raw material, pictures and glass transmission spectra (blue for different densities of the sheet, black for a reference white glass of the same factory)

*

In the previous post I showed some pictures produced by my technique of background removal for making “as accurate as possible” photos of glass sheets.

The photos were taken on a TL back-lighted, which is highly irregular. What you have to do is basically to multiply the picture A by the inverse of the picture B, after calibrating the pictures A & B together by making sure that their background has the same lightness. Of course you should do this in RAW linear 16bit!

This simple operation removes: the optical artefacts (the lens of the camera filters more light in the picture’s borders) the electronic ones (the CCD is slightly non-linear). It also automatically generates a “perfect” white balance, whatever your light source is… The only pity is that it adds some noise, but for our application this is fine.

*

I developed a method for selecting parts of the glass sheets based on their spectral transmission, by combining spectrophotometric measurements, math, and the corrected pictures :

g161-png_deltay_14-0

The 3 zones A, B, C have an average difference of 14% in luminance when Blue-sky light passes through them.

other glass sheets characterized in the same way:

rose_or_clair-png_deltay_10-0

3275xx_2225-png_deltay_10-0

%d bloggers like this: