In this tutorial, architect and illustrator Andreas A Tjeldflaat takes you through the post-production steps of an architecture rendering in Photoshop. The featured techniques focus on marrying a CG building constructed in Modo and rendered using Rhino into a base photo, as well as building up an atmosphere around the structure that supports the aim of the design.
The goal of this image was to blend a Brutalist prison tower into an urban landscape and calm down its overpowering presence. To do this, the image frames the building as a backdrop to an everyday morning scene. The scene is not intended to be photorealistic, but rather to capture the spirit of the construction and its context. Some artistic touches have been added that take the image beyond realism.
The following techniques are applicable to post-production of any CG rendering. Although it can be seen as a step-by-step guide, the process is not as linear as it seems. It inevitably involves going back and forth between layers; adding, adjusting and tweaking, until it feels right.
Time to complete
1 - 2 days
Photoshop CS5 or later
The starting point for all projects such as these is the base photo – having a good one is vital. I imported the image into Modo and used this as a background to the 3D model. I adjusted the camera angle and lens width, and matched the lighting with that of the photo. I then hid the photo as I only wanted to render the CG building.
When rendering – using Rhino for that hard, realistic ‘architectural’ feel – I included Normals, Alpha and Ambient Occlusion channels, as well as the standard RGB channels. These will come in handy later.
Next, I opened the render in Photoshop and created a layer mask of the alpha channel to mask out everything but the building from the RGB layer. I brought in the photo and set it as the background layer. I duplicated the photo and put it in front of the CG building, then used the Pen tool to mask out everything except the buildings that sit in front of the CG building.
I then added Curves and Hue/Saturation adjustment layers above the render to match the rendering to the photo. I put the Ambient Occlusion layer on top of the RGB layer and changed the blending mode to Multiply. This makes the building pop a little more.
The building needed something within the windows to make it appear more realistic, so I pasted in some generic interior spaces from another picture.
Edit > Transform > Distort to match the perspective in the scene, changing the blending mode to Multiply and reducing the transparency to 50%.
I cut out people from photos that fit the perspective and story of the scene. This also gives the image a better sense of scale.
To adjust the lighting of the people, I created a clipping mask layer above each in the Layers panel, and painted with a soft black (shadow) and white (highlight) brush to match the scene lighting. I then changed the blending mode of this layer to Multiply.
Next up was texture mapping, as I wanted to add some roughness to the building’s exterior to make it appear more realistic and less ‘CG’. First, I applied a metal texture to the cladding of the prison. For this, I used a photo of a generic metal surface and again used
Edit > Transform > Distort to fit the perspective of the surfaces.
To avoid the effect overwhelming the CG model, I changed the blending mode to Soft Light, and reduced the opacity to 70%.
I add textures of rusty and flaked metal to the surfaces, using the same technique as in Step 5. Adding these material imperfections ‘aged’ the building and helps it fit in with the other buildings in the photo.
The buildings now needed reflections. To add these, I first duplicated the sky layer (
Ctrl+J), moved it up and used Edit > Transform > Distort to fit it to the building’s surfaces. I masked out the surfaces and reduced the opacity to 35%.
I wanted the lower parts of the surface of the metal cladding to reflect street elements such as the streetlights’ poles and adjacent façades. To do this, I copied elements from the scene photo and mirrored them (
Edit > Transform > Flip Horizontal) and moved them over to the building’s surface. For realism, I applied a Gaussian Blur ( Filter > Blur > Gaussian Blur) with a radius of 1 pixel. I also reduced the opacity to 70%.
I wanted to intensify the lighting in the photo to further enhance the geometry of the building. To achieve this, I created a new layer and used the Normal rendering channel to select the surfaces facing away from the light source and darken these with a black brush.
I did the same with the surfaces facing the light and painted with a white brush. I then changed the blending mode to Soft Light and used this to enhance what was already there.
I gave the surfaces in the photo the same treatment. With a soft black brush with 50% opacity, I darkened the back of the doughnut shop and the cars. I repeated this on the street facades on the left of the image.
To let some light come through the leaves in the tree, I created a new layer and filled it with black. Using a brush with 50% opacity, I painted in dots of white and orange with different sizes in between the leaves. I then changed the layer’s blending mode to Color Dodge.
I added a vignette to the image to enhance the depth of the scene. To do this, I first filled the scene with black and changed the blending mode to Soft Light. Next, I made an elliptical selection touching all four edges of the image and added a feather of 150 pixels.
With the area selected, I made a layer mask and decreased the transparency to 70%.
To give the warm orange glow of the morning sun, I created a new layer and selected a soft orange brush with 30% opacity and painted on the left side of the sky, as well as any surfaces facing the sun. To integrate this into the scene, I changed the blending mode to Soft Light.
To balance this, I created a new layer and did the same with a blue brush on the surfaces that face away from the sun.
To match the rendered photo’s graininess, I added some noise. I filled a layer with grey, and selected
Filter > Noise > Add Noise. I set the Amount to 20% and chose Monochromatic. I then masked out the building and changed the blending mode to Overlay .
Finally, I added a Curves adjustment layer. I pushed the curve down in the left end (Shadows) and up in the right end (Highlights) of the spectre, to make it an S-curve that increases the contrast. This gives the image a last punch.