Match Photo

Match Photo works out where the camera stood when a photograph was taken. You draw a few lines along edges in the photo, and Terrafold sets the view so the model lines up with it. You can then model a house or a garden in the photo's perspective, and paint faces with the photo.

A matched photo is stored with a scene. Going to that scene shows the photo behind the model.

Match a photo

Choose Camera ▸ Match New Photo… and pick a PNG or JPEG image. The photo fills the viewport, and two pairs of lines appear: red for the model's red axis and green for the green axis. There is also a yellow dot for the origin and, once Terrafold has a solution, a yellow horizon line.
Drag the square handles at the ends of the lines. Put each red line along an edge in the photo that runs in one horizontal direction, and each green line along an edge at right angles to it. Two walls of a building, or the edges of a paved area, work well. Keep the two lines of each pair far apart for the best accuracy. The view updates while you drag.
Drag the origin to a point on the ground where the red and green directions meet, such as the corner of a building.
Set the scale. In the Match Photo panel, under Scale: a known length from the origin along an axis, choose an axis, type a length you know (4m, 12') and press Set. Then drag the white handle to the far end of that length along the axis.
Press Done. Terrafold stores the photo with a new scene named after the image. Cancel drops your changes and restores the view.

While you match a photo, the Match Photo ribbon tab offers Done, Cancel, Zoom to Photo and Project Textures from Photo.

Return to a matched photo

Camera ▸ Zoom to Photo returns to the matched view. Orbiting away hides the photo.
Camera ▸ Edit Matched Photo lets you adjust the lines of the selected scene's photo again.

The Match Photo panel

Open it with Window ▸ Default Tray ▸ Match Photo. It lists the scenes that have a photo, with Go and Edit buttons, and has the display settings:

Model and Photo: show or hide each of them.
Opacity of the photo.
Grid: none, on the ground, on the walls, or on all planes, with its Spacing.

Paint faces with the photo

Project Textures from Photo paints the selected faces with the part of the photo that lies behind them. It's a quick way to give a model of a building its real facade.

The projection is exact for triangles and approximate for larger faces seen in strong perspective. It does not take hidden parts into account, so a face behind another one also gets the photo.

Special cases

Tall buildings: three-point perspective

When you look up or down at a tall building, vertical edges converge too. Tick Blue axis lines (three-point perspective) and place the blue lines along vertical edges. With Principal point set to From vanishing points, Terrafold also finds the optical centre of the photo, which helps with cropped photos. The default is Image centre.

Looking straight down a street: one vanishing point

If only one direction converges in the photo, you have two options:

Place the second pair of lines along edges that are parallel in the photo.
Tick Level horizon (one vanishing point), drag the horizon to eye level, and use only the red lines.

The lens can't be measured from a single vanishing point. Terrafold uses the Field of view box instead, which is 35° by default.

The axes point the wrong way

The positive red and green directions point away from the camera, towards where their lines meet. Rotate axes 90° turns the model's axes a quarter turn about the blue axis.

Limits

You can match several photos to the same model, one scene each, but the photos are not blended.
The photo is not included in exported images, renders or the path-traced preview.
In the browser version, Camera ▸ Match New Photo cannot pick a photo yet.