Light it up with Photoshop

This tutorial explains how to diagrammatically represent interior light using the Adobe Creative Suite. But wait, you don’t really understand how to design with light? Don’t fret, this tutorial is meant for purely diagrammatic study, and Section Cut will be releasing a series of How Tos on lighting design soon enough. In the mean time, for a superficial overview read Wikipedia’s article on lighting.

While Reflected Ceiling Plans (RCPs) provide a good tool for documenting locations of light, we experience the world in section and perspective. Sections are fairly straightforward and can be easily manipulated in Photoshop. Vignette images, however, may include aspects of materiality, ambient lighting, and textures that require a greater deal of finesse, and therefore in this how to we’ll focus on diagrammatic drawings meant to convey ideas diagrammatically, and defer photorealism for another day. Ideally, lighting is actually modeled using photometry and simulated using algorithms such as Radiosity (also called Global Illumination), or various forms of Ray-Tracing. However for quick design studies and without the technical skills to use such programs, Photoshop can serve as a low-level buy-in for basic representations. Light diminishes by the square of the distance, so although not perfect, the fade tool in Photoshop provides a reasonable representational tool for this purpose.

Step 1: Construct Base drawings


Sections offer the easiest way to understand interior space, so it serves as a good starting point. First, import your section drawing into photoshop at high resolution (300dpi is ideal), and invert the image: click ctrl+I (command+I on mac).
If you look closely at the image above, the ground poshe is actually a blacker black than the air and building spaces. Depending on your aesthetic this may be a useful technique. Create a black (or dark colored) layer behind your now-white line-work and play with the color and darkness of the background. You may try other dark colors, subtle fades, or other tricks, open to your imagination. Keep adjusting this after you’ve begun lighting the scene.

Vignette Perspectives

In many ways the easiest vignette to start with is a simple line drawing without any shade, shadow, color, texture, or people, allowing you to follow the same process as the Section. There are surely ways of achieving this in any 3D modeling software, but if you’re using Rhino we have a robust process written up in the Make a Sexy Rendering How To; scroll to Step 2 with instructions for downloading view settings and printing an image file.

Step 2. Adding Light

Downlights / uplights

Create a new layer to begin adding lighting. Start with something simple, like a downlight. Use the polygonal lasso to trace out the cone of the light – the cone should be symmetric about a line between the light source and the point it seeks to light. Then, use the fade tool to create the light. I usually use a just slightly yellow-off-white color, and make sure to select the color-fade-to-transparent option. It may take a few tries to get the look correct. Also you can try the different fade options – linear vs pin point.
Once you have your downlight, you can copy it (hold down alt while clicking and dragging with the move tool) as many places as needed.

Wall-washing / grazing / coves

Notice the uplight along the left side (it’s a large screen wall surrounding the project). Spending the time to consider where the light will travel and what is in shadow goes a long way. Direct light to the areas you want, and use the sectional quality of the beam spread to create a beautiful image.

Adding ambient light

The image above is pretty extreme, but you may desire a bit less contrast depending on the aesthetic, or if walls beyond are lit. select the surface you wish to light, then use the fade tool to create the effects, one surface at a time. A lighter feeling may also be achieved by lightening the background color.

Step 3. Alternate Methods

Beyond the basic diagrams explained above, there may be the opportunity to try out lighting within a photograph of an existing space, or within a more resolved rendering. The two videos below, although containing amusing and slightly off-topic subjects, serve to illustrate additional techniques in Photoshop.

Here is an easier process, with a more…amusing subject:

As always, please comment with any questions or ideas on this or other How To posts. Feel free to share your final drawings with us on Facebook or Twitter if you’ve used the information on this page to light up your drawings! We’d love to hear from you.

The header image was produced by the author at Lam Partners, of Safdie Architects’ National Campus for the Antiquities of Israel.

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