The first thing you'll need to do is go out and take pictures of your subject, and measure its dimensions. Step far back from your object and use the telephoto to reduce distortion caused by wide-angle lenses. Try to get a photo of every side of the object, taken at a perpendicular angle to the sides of the object. For example, for the roof of a house or the hood of a car you will need to find a high vantage point to photograph the surface face on.
While you are photographing, measure all the dimensions of the object. Take note of the exact placement of windows and doors or other details, it will make the next steps easier.
Next, create a skeleton diagram from your measurements in a vector drawing program such as Adobe Illustrator or equivalent. Choose a scale for the model and get out the calculator. Draw lines to indicate the placement of doors and windows or other details.
From the wireframe skeleton, create the pieces for a blank white model of your object. Complete all pieces of the entire model, test build it and make adjustments to get the fit of the model just right before proceeding to the next step.
Pasting the Photographs
To begin adding photographs to the blank model, choose one piece to work on at a time. A larger piece such as the wall shown above can be divided into several subsections, divided along seams of the subject, such as where a window meets a wall, or corner.
Going back to the vector drawing in Illustrator, select and copy a path outline of a subsection of the wall. Open a new Photoshop document at 300dpi and slightly larger than the outline. Paste the path into the Paths palette. You can copy and paste several paths at a time to include the outlines of windows and doors or other details from your wireframe diagram.
On a new layer, choose Stroke Path from the Paths flyout menu to draw an outline showing the shape that the photo will have to fit into to match the blank model piece.
Paste a photo onto another layer and scale it to the correct size, using the Free Transform tool.
Using the outlined path from the previous step as a guide and adding horizontal and vertical guides, you can see how much to stretch the photo to fit within the shape exactly. With some practice, you can select and stretch particular parts of the photo to straighten them out.
Distortion from the Lens
If your photos were taken close to the subject, they may appear to bulge outward by the natural distortion of the wide-angle lens. One crude method to straighten the "bulge" of these photos is to use the Pinch filter (Filter > Distort > Pinch) using a small amount between 2-5. Draw some guides before using the filter to test the correct result.
If you are using Photoshop CS, a better method is to use the Lens Correction filter (Filter > Distort > Lens Correction). Adjust the distortion slider on top and vertical and horizontal perspective sliders to straighten the photo to match the guide lines of the grid.
It may be difficult to get a clear view of all sides of your subject. Here a parked car and street sign are obscuring part of the wall of the building. But by stepping sideways a few feet to take a second photo, the sign is blocking a different area.
Cut a small section from one photograph and paste it onto the other to have a complete wall. The area behind the parked car will require much more work to create a section of wall from scratch. If it were a brick wall or other simple pattern, it'd be a lot easier to fill in!
For other areas of you may have to get creative. By collaging several photos together and using the Free Transform tool, you can cover every side of the object, even if you can't get a straight photo of it.
Just remember that the beauty of a photorealistic model is in the fine detail and specific texture of the photograph. So even if you end up cloning sections of wall to fill in wide areas, you should make every area of the photo look unique, natural and interesting. Every brick on a wall has a unique color and weathering, it is not just a repeated wallpaper pattern.
Assembling the Pieces
After you have collaged and stretched and distorted the photo to fit within its shape, you can use the same outline path to select just the parts of the photo within the path. From the Paths flyout menu, choose Make Selection from Path.
Copy and paste the selected area of the photo into a new blank Photoshop file, where you will assemble the completed subsections of the photo. You can use the eraser and paintbrush to hide the seams between subsections, if necessary, or adjust colors, to get the picture looking perfect.
When your Photoshop file is ready, go back to the plain white model you made in the first step and place the artwork behind the blank outlines of the pieces. Because you used the same wireframe paths to trim the photos, they should fit exactly at the same size as the blank pieces. Perfect!
Download the finished Ohio House Motel