Here's the text that describes the procedure in PhotoMatch:
Matching an Existing 3D Model to a Photo's Context
Use Photo Match to match an existing 3D model to a photo's context. To match an existing 3D model to a photo's context:
- Take a digital picture of the location where you will place your building. This photo might or might not have an existing building where the model will be located.
- Select the Open menu item from the File menu. The Open dialog box appears.
- Navigate to your model.
- Select the model.
- Click Open. The model appears in the drawing area.
- Select the Match New Photo menu item from the Camera menu.
- Navigate to the photo where you want to place your building or structure.
- Click on the photo. The photo is selected.
- Click Open. The photo will appear in the drawing area on its own scene in SketchUp. You are also placed in a Photo Match session where you will calibrate SketchUp's camera to duplicate the position and focal length of the camera used to take the photo . The words "Photo Match" appear in the upper-left of the drawing area. Finally, the Match Photo dialog box appears. Refer to Photo Match Session Controls and Context-Menu Items for further information.
- Click and hold the cursor on the origin. The cursor changes to a hand.
- Move the cursor to a distinct origin-like point on photo (where three axes might intersect, such as bottom corner of building).
- Release the mouse button. The origin is established.
- Uncheck the Model checkbox in the Match Photo dialog box. The model will be hidden.
- Click on an red axis bar grip (). The cursor changes to a hand.
- Move the cursor to the starting point of a position on the photo representing a line parallel to the red axis.
- Release the mouse button.
- Click on the other red axis bar grip (). The cursor changes to a hand.
- Move the cursor to the ending point of a position on the photo representing a line parallel to the red axis.
- Release the mouse button. The first axis bar is aligned to the red axis.
- Repeat steps 9 through 14 for the remaining three (one red and two green) axis bars.
- Check the Model checkbox in the Match Photo dialog box. The model will reappear, oriented correctly to the photo (but likely not-to-scale with the photo).
- Click and hold on any of the axes. The cursor will change to two opposing arrows ( ).
- Move the cursor up or down the axis to scale your model. Your model will scale to fit the photo.
- (optional) If your photo contains an existing building that is now represented by your model, click the Project textures from photo button in the Match Photo dialog box to project.
- Context-click to invoke the Photo Match session context-menu.
- Select Done. You are placed in a sketch-over-image session. This mode, unlike normal SketchUp drawing mode, is a 2D drawing mode. The words "Sketch Over" appear in the upper-left of the drawing area. See Sketch-Over-Image Session Controls and Context-Menu Items for further information.
Caution - Tools that manipulate your point of view force you out of a Sketch-Over-Image session into normal SketchUp drawing mode. These POV tools are the Orbit Tool, Position Camera Tool, Walk Tool, and Look Around Tool.
Note: Make sure that the model axes correspond to those of the photomatch before you import the model (rotate the model before you import, if necessary).