Creating Shadows for Plan Drawings



Shadows on plans help drawings read spatially. This tutorial explains how to edit a shadow render for a plan drawing.
Uses Tool(s) Rhinoceros , Photoshop CS5 , Illustrator CS5 , Live Trace


Rendering Plan Shadows

A common application of Live Trace is to create shadows for a site plan to emphasize how the buildings fit into the context of the site. They may not be indictive of true lighting conditions, but they help the drawing read spatially. Shadows that cut through the building can also be added to floor plans to demonstrate wall height and openings within that floor.

In order to add shadows to a plan, they need to be rendered in the the Top viewport using Rhino Render . First, add a directional light to the 3D scene by using the DirectionalLight command. The light's direction and angle will determine the direction and depth of the shadow. Next, zoom in to the area whose shadows will be rendered and click on the Rhino Render button in the Toolbar (an icon of a blue circle). The rendering window will pop up with the image of the plan shadows. Save the image by clicking File->Save As in the render window.

To make sure that the outlines of the shadow are crisp, click Render-> Render Properties . Make sure the image size and resolution are sufficient to create a clean image (1600 x 1200 pixels at 300 DPI is usually enough).


Editing the Shadows Image in Photoshop

The render image's contrast and brightness need to be edited in Photoshop to ensure a clean trace of the shadows. There are two steps to this after opening the image in Photoshop.

To adjust the levels, click on Image->Adjustments->Levels . Drag the gray slider to the left to make the mid-gray tones appear brighter. This makes the darker shadow appear darker and clearer. Check the Preview box to see what the image will look like as you edit it. Click OK.

To adjust the contrast, click on Image->Adjustments->Brightness/Contrast . Increase the contrast to bring out the shadows further. Check the Preview box to see what the image will look like as you edit it. Click OK.

It is helpful to crop the image to just the building so that the shadows that are traced are just for the plan. Then, save the image.

Live Tracing the Shadows in Illustrator

Open the edited shadow render in Illustrator . Select the object and preview the final tracing by opening the Live Trace Options . Select a preset option and then change the Path Fitting options to create a more precise trace with sharp corners. Select the Ignore White option so that the background does not become its own object. After tracing, expand and ungroup the object so that the outline's anchor points can be edited if they have not been traced cleanly.

Review the basics of the Live Trace tool if you are having trouble.


Inserting the Shadows into Plan Drawing

Open the original plan drawing in Illustrator. Create a new layer for the shadow. Click on the Options button in the Layers panel and make sure that Paste Remember Layers is not selected. Paste the shadows on to the new layer in the original plan file.

Because the shadows were created using a render image that did not have a scale, they will not match the plan at first. Open the Transform panel by clicking Window->Transform . To scale the shadow drawing, select it and edit its overall width and height. Make sure that the lock icon next to the width and height options is depressed so that the overall proportions of the shadows are maintained.

The shadows should be made slightly transparent so that they do not detract from the linework already existing in the plan drawing. Open the Transparency panel by clicking Window->Transparency . Select all of the shadows by clicking on the circle next to the layer name. Change the Opacity to 20% or less. The color of the shadow can also be edited by changing the fill color.

Because the shadows are now vector linework, they could also be opened in Rhino or AutoCAD for further drafting purposes.

Common Problems