Matching Photos and Models

Use the Match New Photo and Edit Matched Photo menu items to create a 3D model to match a photo or to match an existing 3D model to a photo's context. Activate the Match New Photo and Edit Matched Photo menu items from the Camera menu.

SketchUp is commonly used to create designs of buildings or structures. SketchUp allows you to create these designs using the actual real-world scale (a scale of 1:1 where a unit of measurement in SketchUp represents that actual unit of measurement in the real world). However, digital pictures are not at a 1:1 scale. Therefore, to create a 3D model that matches a photo (or to match an existing SketchUp model to a scale in a photo), you must calibrate SketchUp's camera to match the position and focal length of the digital camera used to take the picture. Matching consists of 4 high-level steps:

1. Take digital pictures of a building or structure. See Taking Digital Photos for Use When Matching for further information.
2. Start matching. Matching involves loading a digital picture and calibrating SketchUp's camera to the position and focal length of the camera used to take the actual photo (you are setting up the exact criteria used to take your picture so you can draw on the picture). You can also set the scale of the actual building or structure while matching, or just resize the entire model after it has been drawn.
3. Start sketching. Once you have duplicated the position and focal length of the camera used to take the picture, you can draw over the image in SketchUp. SketchUp moves into a 2D sketching mode from matching (it is 2D because you are drawing on a 2D photo that needs to be oriented at a specific camera angle to you).
4. Repeat Step 2 and 3 with any other photos that make up the building or structure.

Creating a 3D Model to Match a Photo

Use the matching process to create a 3D model to match one or more photos of a building or structure. This process is best suited for making models of images that have parallel lines, such as the top and bottom of a square window. To create a 3D model to match a real-world building or structure:

1. Take digital pictures of the building or structure. See "Taking Digital Photos for Use When Matching" for further information.
2. Select the Match New Photo menu item from the Camera menu. The Select background image file dialog box is displayed.
3. Navigate to the first photo in the series of photos for your building or structure.
4. Click on the first photo in the series of photos for your building or structure. The photo is selected.
5. Click the Open button. The photo will appear in the drawing area on its own scene in SketchUp. You are also placed in a matching mode where you will calibrate SketchUp's camera to duplicate the position and focal length of the camera used to take the actual photo . The words "Match Photo" appear in the upper-left of the drawing area. Finally, the Match Photo dialog box appears. Refer to matching Controls and Context-Menu Items for further information.
6. Click and hold the cursor on the origin. The cursor changes to a hand.
7. Move the cursor to a distinct origin-like point on photo (where three axes might intersect, such as bottom corner of building). The origin you use depends on the photo:
   • For photos that are usually taken indoors where walls, ceiling, and floor of a room meet at a corner, the origin is usually at the bottom corner where the walls, ceiling, and floor meet. 
   • For photos that are taken from a vantage point where you are looking down on the building or structure, the origin would be at the top corner of the building where roof and walls meet.
   • For photos that are taken from a vantage point where you are standing on the ground, the origin would be the bottom corner where the walls and ground meet.
8. Release the mouse button. The origin is established.
9. Click on an red axis bar grip. The cursor changes to a hand.
10. Move the cursor to the starting point of a position on the photo representing a line parallel to the red axis.
11. Release the mouse button.
12. Click on the other red axis bar grip. The cursor changes to a hand.
13. Move the cursor to the ending point of a position on the photo representing a line parallel to the red axis.
14. Release the mouse button. The first axis bar is aligned to the red axis.
15. Repeat steps 9 through 14 for the remaining three (one red and two green) axis bars.
16. Context-click to invoke the matching context-menu.
17. Select Done. You are placed in a sketching mode. 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. Refer to Sketch-Over-Image Controls and Context-Menu Items for further information.
18. Sketch on photo using the SketchUp drawing tools.

Caution - Tools that manipulate your point of view force you out of Sketch-Over-Image mode into normal SketchUp drawing mode. These POV tools are the Orbit Tool, Position Camera Tool, Walk Tool, and Look Around Tool.

19. Repeat steps 2-12 with other sides (photos) of the building until building or structure is done.

Matching an Existing 3D Model to a Photo's Context

Use the matching process to match an existing 3D model to a photo's context. To match an existing 3D model to a photo's context:

1. 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.
2. Select the Open menu item from the File menu. The Open dialog box appears.
3. Navigate to your model.
4. Select the model.
5. Click Open. The model appears in the drawing area.
6. Select the Match New Photo menu item from the Camera menu. The Select background image file dialog box is displayed.
7. Navigate to the photo where you want to place your building or structure.
8. Click on the photo. The photo is selected.
9. Click Open. The photo will appear in the drawing area on its own scene in SketchUp. The photo will appear in the drawing area on its own scene in SketchUp. You are also placed in a matching mode where you will calibrate SketchUp's camera to duplicate the position and focal length of the camera used to take the actual photo . The words "Match Photo" appear in the upper-left of the drawing area. Finally, the Match Photo dialog box appears. Refer to Matching Controls and Context-Menu Items for further information.
10. Click and hold the cursor on the origin. The cursor changes to a hand.
11. Move the cursor to a distinct origin-like point on photo (where three axes might intersect, such as bottom corner of building).
12. Release the mouse button. The origin is established.
13. Uncheck the Model checkbox in the Match Photo dialog box. The model will be hidden.
14. Click on an red axis bar grip. The cursor changes to a hand.
15. Move the cursor to the starting point of a position on the photo representing a line parallel to the red axis.
16. Release the mouse button.
17. Click on the other red axis bar grip. The cursor changes to a hand.
18. Move the cursor to the ending point of a position on the photo representing a line parallel to the red axis.
19. Release the mouse button. The first axis bar is aligned to the red axis.
20. Repeat steps 9 through 14 for the remaining three (one red and two green) axis bars.
21. 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).
22. Click and hold on any of the axes. The cursor will change to two opposing arrows.
23. Move the cursor up or down the axis to scale your model. Your model will scale to fit the photo.
24. (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.
25. Context-click to invoke the matching context-menu.
26. Select Done. You are placed in a sketch-over-image mode. 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 Controls and Context-Menu Items for further information.

Caution - Tools that manipulate your point of view force you out of Sketch-Over-Image mode into normal SketchUp drawing mode. These POV tools are the Orbit Tool, Position Camera Tool, Walk Tool, and Look Around Tool.

Editing a Previously Matched Photo

There are two options to resume matching . These options are:

• Select the photo you were matching from the Camera > Edit Matched Photo sub-menu.
• Context-click on the Scene tab for the photo you were matching and select Edit Matched Photo.

Resuming Sketch-Over-Image Mode

Click on the scene tab that represents the photo to return to sketching over the image.

Matching Controls and Context-Menu Items

There are three sets of controls that are accessible from the matching mode. These controls are: The matching controls, Match Photo dialog box controls, and the matching context-menu items.

Matching Controls

Use the matching controls to adjust the axis such that you can draw a model to match a photo or match a model to a photo.

Origin: The origin represents the point where all axes in SketchUp originate. Click and hold on the origin to select the origin. Move the cursor to reposition the origin.

Red and Green Axes bars: The red and green axes bars are used to align the camera to a photo. Click and hold the axes bar grips to reposition the axes bars.

Axes lines: The axes lines represent the 3 dimensional axes and help to establish the vanishing points. Click and hold on the axis line to select the axis line. Move the cursor along the axis line to resize a model.

Vanishing points: There are three vanishing points in the matching mode (red, green and blue). The vanishing point is a place along the horizon of a perspective photo where all the parallel lines seem to converge. Click and hold on a vanishing point to select the vanishing point. Move the cursor to reposition the vanishing point.

Match Photo Dialog Box

The Match Photo dialog box controls are used to help you create accurate 3D models from photos and to accurately place models in a photo's context.

New Matched Photo: Click on the New Matched Photo button to start a new matching.

Edit Matched Photo: Click on the Edit Matched Photo button to reenter the matching mode. This button is only active in a Sketch-Over-Image mode.

Photo: Check the Photo checkbox to display the photo. Uncheck the Photo checkbox to hide the photo. This option is also available in sketch-over-image mode.

Opacity: Move the Opacity slider to the left to make the photo more transparent. Move the Opacity slider to the right to make the photo more opaque. This option is also available in sketch-over-image mode.

Model: Check the Model checkbox to display the model. Uncheck the Model checkbox to hide the model. This option is also available in sketch-over-image mode.

Project Textures From Photo: Click on the Project textures from photo button to automatically project the photo as a texture onto your model.

Grid: Check the On radio button to continuously display the axes grid. Check the Auto radio button to only show the grid when manipulating one of the matching controls.

Style: Click on the Style icons to change the style of the grid. Grid styles are used to set the grid to best complement a specific type of photo. The left-most style is used for photos that are usually taken indoors where walls, ceiling, and floor of a room meet at a corner (the origin is usually at the bottom corner where the walls, ceiling, and floor meet). The middle style is used for photos that are taken from a vantage point where you are looking down on the building or structure (the origin would be at the top corner of the building where roof and walls meet). Finally, the right-most style is used for photos that are taken from a vantage point where you are standing on the ground (the origin would be the bottom corner where the walls and ground meet).

Planes: Click on the planes buttons to toggle the display of grid lines on a particular plane. The Red/Green button toggles grid lines in the red and green planes. The Red and Blue button toggles grid lines in the red and blue planes. Finally, the Green/Blue button toggles grid lines in the green and blue planes.

Spacing: The spacing field is used to set the scale of your model before you start sketching over the image. Enter a value in the spacing text-entry box to change the size of grid spacing to represent some multiple of the overall structure size. Then, drag the axes lines to line grid squares up with your image. 

Matching Context-Menu Items

Context-click during matching to display the matching context-menu.

Done: Select the done menu item to end your matching.

Start over: Select the Start Over menu item to restart matching.

Cancel match: Select the Cancel Match menu item to cancel and exit your matching.

Zoom matched photo: Select the Zoom matched photo menu item to fit the entire drawing area.

Zoom vanishing points: Select the Zoom vanishing points menu item to zoom to fit all vanishing points in the drawing area.

Rotate 90 left: Select the Rotate 90 left menu item to rotate the red and green axes 90 degrees left. Use this menu item primarily when creating a model to match several photos (to rotate the model as you draw the model's sides to match the different sides of the structure in different photos).

Rotate 90 right: Select the Rotate 90 right menu item to rotate the red and green axes 90 degrees right. Use this menu item primarily when creating a model to match several photos (to rotate the model as you draw the model's sides to match the different sides of the structure in different photos).

Undo: Use the Undo menu item to undo the last matching command.

Redo: Use the Redo menu item return the last undo to its previous state.

Sketch-Over-Image Controls and Context-Menu Items

There are three sets of controls that are accessible from a Sketch-Over-Image mode. These controls are: The SketchUp tools, Sketch Over dialog box controls, and the Sketch-Over-Image context-menu items.

Sketch-Over-Image Context-Menu Items

Context-click during a Sketch-Over-Image to display the Sketch-Over-Image context-menu. 

Edit Matched Photo: Select the Edit Matched Photo menu item to resume matching .

Project Photo: Select the Project Photo menu item to project the photo's texture on your model.

Zoom Matched Photo: Select the Zoom Matched Photo menu item to fit the entire drawing area.

Sketch Over Dialog Box Controls

The Sketch Over dialog box controls are used to help you create accurate 3D models from photos and to accurately place models in a photo's context.

Photo: Check the Photo checkbox to display the photo. Uncheck the Photo checkbox to hide the photo. This option is also available during matching.

Opacity: Move the Opacity slider to the left to make the photo more transparent. Move the Opacity slider to the right to make the photo more opaque. This option is also available during matching.

Model: Check the Model checkbox to display the model. Uncheck the Model checkbox to hide the model. This option is also available during matching. 

Taking Digital Photos for Use When Matching

Your success with matching depends highly on the quality of photographs taken of your building or structure. Following are a few tips regarding matching photographs.

• Sketch Over Image works best on pictures of structures composed of predominantly right angles and taken at a roughly a 45 degree angle from a corner.
• The images should not be distorted and should be of a “reasonable” resolution.
• Barrel distortion typically comes from wide angle lens cameras, and users should use a third party product to eliminate it from images prior to using them within SketchUp. All cameras have a little bit of this distortion, typically worse around the edges of the image, and we have a simple tool for compensating for this visually.
• There are many other kinds of subtle lens distortions which I won't go into. Ultimately, we assume that perfectly straight lines in the original object are shown as perfectly straight lines in the photograph.
• Cropped (or expanded) images. A cropped image, or one which has been expanded to have extra white space around it, will not have the ‘center of projection’ in the center of the image. Sketch Over Image currently requires that the point you aimed the camera at is located in the center of the image. Although it may seem possible to use an image like this, typically, vertical lines will not align well across the image and the results will be unsatisfactory.
• Warped images. Images which have been manually warped via an image processing program, or specialized camera are not supported. For example, some cameras used for architectural photographs adjust for vertical perspective distortion, by tilting the camera plane. The resulting photo is an image similar to our “Two Point Perspective” mode.
• Stitched images (for example panoramic images). These images are typically excessively warped and will have multiple vanishing points for each axis.
• Non right angle models. Sketch Over Image relies on SketchUp's red/green/blue axes and limits most drawing to the axis planes. The more right angled reference lines in the original image, the better results you will get. Sketch Over Image will also struggle with: - Vanishing points which are at infinity. This happens in two common situations. A one point perspective, for example, an image which is looking down a hall way, will be difficult to align because you only adjust one vanishing point and the other two are far away. Likewise, an image taken with a very long tele-photo lens (or say a satellite or aerial image) will not have very useful vanishing points and will be difficult to align.
• Extremely high resolution images. Images are currently embedded within the skp file and duplicated when made into a material. This makes for large model sizes. There is also no resolution control over the export process and this may be a problem when exporting to GE (for example).
• Excessive foreground. If there are trees and other foreground objects blocking the view of the building, it may be difficult to Sketch Over top of the image.