A common postprocessing task in arch-projects is adding in various 2D assets to finish off the image. It usually involves scattering people to give a sense of scale to the scene, along with other things like trees, road signs and so on. These will all need shadows to ‘ground’ them in the image.
Techniques for shadows will vary depending on the scene. In general, diffused lighting will give a general soft darkening around the asset. The diffused lighting could come either from a series of interior lights, or perhaps an exterior scene on a cloudy day, with the clouds diffusing the direct sunlight.
Shadows for these scenes tend to be easier to produce, often just needing a soft-edged brush gently applied to a multiplied layer positioned below the asset in the layer stack. For these, add a very general darkening to the area around the asset, with a more focused darkening near where it meets the ground (around the edges of the shoes, for example). Also pay attention to where the asset is positioned in the scene – standing near a wall may require a slight darkening of the wall too.
The following three steps should help your shadows to become more convincing. Photoshop will be used for it and the cutout image comes courtesy of the kind folks at VYONYX (http://vyonyx.com).
Create a shadow form. Assuming your asset is a cutout image on its own layer, make a duplicate layer below and Free Transform it to project along the ground. Whether or not you need to mirror it will depend on the angle of the sunlight. Pay attention to where the shadow meets landscape features – you may need to splice several ‘shadows’ together to get them to fall convincingly over curbs, walls and so on.
Temporarily lock the transparency of the layer and fill it with a solid colour. The colour will depend on the temperature of the ambient and diffuse light in the scene – if it’s an exterior day scene, usually a mid grey-blue will do (I used RGB 115, 152, 177 here). Interior atria or dusk shots might need a warmer yellowy-grey. Change the blending mode to Multiply and tweak the opacity until it matches other shadows in the scene. Use the Hue/Saturation adjustment to make final tweaks to the colour.
Shadows tend to become more blurred as the distance between them and the object increases: look at the lamppost shadow in the main image. Using a Blur filter, soften the shadow edges further away, leaving the shadow crisp near to where it meets the asset. Finally, distort the shadow based on what it’s falling on – shadows on grass tend to be quite choppy, so use the Smudge tool to break down edges where needed.
Further information: This Q&A tutorial was written by Derek Jackson (www.djillustration.com) for issue 30 of 3D Artist. The magazine is available to buy as a back issue from the official Imagine Publishing online store here.
Images: © Imagine Publishing