With this tutorial, I wanted to show the workflow that I use to develop a clean looking architectural site plan. This tutorial, like many of my tutorials, doesn’t use a rendering engine, only Sketchup image exports and Photoshop. Although I don’t use a rendering engine, a rendered roof plan of a building could easily replace the Sketchup images used in this explanation.
1) Start with an aerial image of the site at as high of a resolution as you can get it. I prefer to use aerial satellite images for site plans because it adds detail and texture that is hard to get with a 3d model.
2) Once the site plan is opened in Photoshop, go to “Image>Adjustments>Desaturate”.
3) I have topography line work but I want to remove the white background and I also want the line work to be white, not black. To do this, first invert the topography image. Go to “Image>Adjustments>Invert”.
4) Now that the image is inverted, go to the layer blend mode drop down menu in the layers pallet and choose “Lighten”.
The site plan should look something like this….
5) Next, 3 images of the building design need to be exported from Sketchup. Basically, one image will be the color, one will be the line work, and one will be the shadows. It’s important to export each image individually so that each can be edited separately. Also double check that the shadows in the Sketchup model are going in the same direction as the shadows in the aerial photo.
6) Open the “Shaded with textures” SU export in Photoshop and scale it to the correct site. Some time will need to be spent editing out the background so that just the building is visible.
7) Open the “Line work” SU export in Photoshop. Set the layer blend mode to “Multiply” to remove the white background. Lower the opacity so that the line work isn’t too strong. The only reason I am using the line work is to add a little detail to the roof plan.
8) Open the “Shadows” SU export in Photoshop. Choose “Image>Adjustments>Levels”.
9) Move the left slider to the right until the shadows are completely black.
10) Set the layer blend mode of the shadows layer to “Multiply” to remove the white background.
11) Select the “Smudge” tool and set the strength to 92%. Slightly smudge the edge of the shadows not touching the building.
12) Select the “Eraser” tool and give the eraser a soft brush with 25% opacity. Begin slowly erasing the edge of the shadow not touching the building. The corner where the shadow meets the building should be the darkest.
13) Create a new layer and move it below the building layers. A little color will be added to the background.
14) Select the “Paint” brush and give it a soft brush with 50% opacity. Paint in the color radiating from the building. I do this so that the design becomes the focal point and the color stays somewhat consistent.
15) Set the layer blend mode to “Overlay” to set the color into the image.
I have used this technique to create many of my site plans in school. It’s quick and looks like it took more time than it really did which is always a good thing.