How to Set Up for Photo-Matching in SketchUp

By Aidan Chopra

Modeling with SketchUp’s photo-matching feature is generally a step-by-step procedure. Whether you’re building a new model or lining up an existing model with a photograph, start by getting your modeling window ready. How you do this depends on which one you’re trying to do:

  • Line up a model you’ve built already with a photograph: This case requires you to re-orient your view and then reposition your drawing axes before you’re ready to begin photo-matching. To do this, follow these steps:

    1. Orbit around until your model view more or less matches the camera position in your photograph.

    2. Choose Tools→Axes and then click to place your axis origin somewhere on your model.

      The axis origin is where your colored axes meet. Try to choose a spot that’s also visible in your photograph, if there is one.

    3. Click somewhere in the lower-left quadrant of your modeling window.

      This ensures that the red axis runs from the upper-left to the lower-right corner of your screen.

    4. Watch your linear inferences to be sure that your repositioned red axis is parallel to some of the edges in your model.

    5. Click somewhere in the upper-right quadrant of your modeling window to make sure that the blue axis is pointing up.

  • Use a photograph to build a model: Open a fresh, new SketchUp file, and you’re good to go.

After your modeling window is set up, follow these steps to create a new matched photo in your SketchUp file:

  1. Choose Camera→Match New Photo.

    A dialog box opens.

  2. Select the image on your computer that you want to use and click the Open button.

    The dialog box closes, and you see the image you chose in your modeling window. You also see a jumble of colorful techno-spaghetti all over the place. Don’t worry — it’s all part of the photo-matching interface.

    image0.jpg

    SketchUp’s photo-matching feature requires that you use certain kinds of photographs for it to work properly.

  3. In the Match Photo dialog box (Window→Match Photo), choose the style that matches your photograph.

    The style buttons in the Match Photo dialog box correspond to three types of photographs you may use:

    • Inside if your photo is an interior view

    • Above if it@’s an aerial shot

    • Outside if your photo is an exterior view taken from a human vantage point

      image1.jpg

  4. Begin positioning the perspective bars, starting with the two green ones, by lining them up with any two parallel edges.

    The tops and bottoms of windows are good candidates, as are rooflines, tabletops, and ceiling tiles. Take a deep breath — this is easier than it looks. Move each perspective bar one at a time, dragging each end into position separately.

    The following tips can help you position the bars correctly:

    • Zoom in and out (using the scroll wheel on your mouse) to better view your photograph while you place your perspective bars. The more accurately you place the bars, the better things will turn out.

    • Match your perspective bars to nice, long edges in your photograph; you get better results that way.

    • If you’re working with an existing model, hiding it while you place your perspective bars may help; sometimes a model gets in the way. Just deselect the Model check box in the Match Photo dialog box to temporarily hide it.

  5. Line up the two red perspective bars with a different set of parallel edges — just be sure that these parallel edges are perpendicular (at right angles) to the first pair.

    If the parallel edges aren’t perpendicular to the first set of edges, photo-matching doesn’t work.

  6. Drag the axis origin (the little square where the axes come together) to a place where your building touches the ground.

    This is how you tell SketchUp where the ground plane is. Try to make sure your axis origin is right at the intersection of two perpendicular edges.

    If you’re photo-matching an existing model, dragging the axis origin moves your model, too. Line up your model with the photograph so that the spot where you placed the axis origin is right on top of the corresponding spot in your photo. Don’t worry about size right now; you deal with that in a moment.

  7. Roughly set the scale of your photograph by clicking and dragging anywhere on the blue scale/vertical axis line to zoom in or out until your photograph looks to be at about the right scale.

    Do this by first setting your grid spacing in the Match Photo dialog box and then using the grid lines in your modeling window to eyeball the size of your photo until it looks about right.

    If you’re trying to match an existing model to your photo, just zoom in or out until your model looks like it’s the right size. You don’t have to be very exact at this stage of the game. You can always scale your model later by using the Tape Measure tool.

  8. Click the Done button in the Match Photo dialog box.

    When you click the Done button, you stop editing your matched photo. All the colorful lines and grips disappear, and you’re left with the photo you brought in, your model axes, and your thoughts. It may have seemed like a lot of magic, but what you did was pretty simple:

    You used photo-matching to create a scene with a camera position and lens settings that match the ones used to take the picture that’s on your screen. In effect, you’re now “standing” exactly where the photographer was standing when the photograph was taken.