One of the more interesting problems in lighting an architectural illustration is depicting natural sunlight’s effect on an interior space.
Traditional buildings with a limited number of punched windows can be quite dark during the daytime. A person walking through such a space might have no problem maneuvering around furniture, but a photograph will show considerable darkness, and reading away from the window would require artificial lighting.
On the other hand, a modern atrium surrounded by glass seems no different from an outdoor space. Direct sunlight is strong, and even an overcast day affords enough light to read by.
But what about a structure with a solid opaque roof, and glass walls on one or more sides? In that case the architect or illustrator should test different sun angles to see which presents the space in the most flattering way. The following project presented just such a choice, and is related here to suggest one solution among many. Note: this is one of my “ancient” projects, produced in a one bedroom apartment – I am frankly surprised that I still have the preliminary drawings reproduced here.
The La Caixa bank of Barcelona, Spain had two buildings which needed an interior connecting walkway. The firm of Pei Cobb Freed Architects was commissioned to produce a design. The red bar connecting the white model buildings gives a rough idea of the location and context of the walkway.
Above is a quick modeling of the walkway presented as a section perspective.
Here is the same view with further development of the existing building.
The following four views show variations on the idea of a one point perspective seen as if walking within the structure. The changes from view to view are minor, but were important to the client’s need to see the water feature on the right, the detailing of the walkway itself, and the entry plaza outside the walkway on the left.
The image immediately above is a line printout of the final chosen view.
Now for the question of sun angle… The following 3 sketches present 3 different sun positions. Each emphasizes a different aspect of the design, and provides a different focus for the composition. (These sketches are pencil and pastel on 8.5x11 inch bond xerox of the layout)
Sketch 1 uses a high angle sun from the right. Because of the configuration of the water feature this angle will actually downplay the effect of the splashing water. In addition the railings of the moving sidewalks will obscure the shadow line on the floor. The only thing that recommends this sun angle is the diagonal shadow on the far entry wall outside the walkway on the left, which nicely frames the white Picasso sculpture.
Sketch 2 shows a high angle sun from the left. The dappled light on the floor and columns creates a pleasant and warm atmosphere, while the partially shadowed water is a nice distraction.
Sketch 3 brings the afternoon sun deeply into the space. The water feature is well lit, and the whole walkway will receive lots of reflected light. I also liked the dynamic feel of the large light area on the left balanced by the water on the right. The client preferred this sketch, and I spent time refining some of the reflected light effects, such as warm tones on the ceiling to the left, and the dappled “caustics” reflecting off the water on the ceiling to the right. The tree shadows were clunky, but I figured that could be resolved later.
Above are further studies working out people, tree and light placement.
And above is the final. It is about 16x21 inches, and was done with airbrush acrylics on matte photographic paper. I can pick it apart now, but for the time and technology (and the experience I brought to it)… not bad. I am still proud of the handling of the light in this rendering, especially the ceiling reflections, but I was still struggling with the tree shadows when time ran out.
The moral of the story… When dealing with spaces like this, the sun angle is a major factor. Bringing the sunlight into the space can change the entire composition, set an inviting mood, and convey an entertaining story. In short, light can spark the imagination.