# Autopano Pro - Panorama Editor - Geometry Correction

This documentation is for versions 3.0 to 3.0.8.

The following tools are used to correct the geometry:

## PROJECTION

#### Planar or rectilinear projection

Good choice if the angle is low, recommended for architectural shots because it is the only mode that does not curve lines that are deemed to be straight lines.
Can be used only if the view angle is less than 180 degrees along the diagonal of the image, practice shows that beyond 90 degrees the stretching of the image is already visible along the edges and in the corners.
Beyond 120 degrees, the result is no longer acceptable, because the stretching of the image causes an unpleasant loss of sharpness.

#### Cylindrical projection

Can be used up to 360° (horizontally).
The lines parallel to the horizon (curbs, tops of buildings) are still more or less curved.
The vertical angle is limited, it is imperative that it is less than 160 ° but the stretching begins to slightly deform at the top and bottom of the image when it exceeds 45 degrees above or below the skyline.

#### Mercator projection

Can be used up to 360° (horizontally). The effect of stretching up and down the image is attenuated compared to the spherical projection.
The lines parallel to the horizon (curbs, tops of buildings) are still more or less curved.
The vertical angle is limited, it is imperative that it is less than 160 ° since the stretching begins to slightly deform at the top and bottom of the image when it exceeds 55 degrees above or below the skyline.

#### Spherical or equirectangular projection

Authorizes the assembly of all panoramas.
For the direct display (without a viewer) of a panorama on the screen and for feel we need to ensure that the curvature of parallel straight lines on the horizon is still acceptable (there is no rule, you need to be the judge).
When the vertical viewing angle is large, the stretching effect at the top of the image (near the zenith) and at the bottom of the image (near the nadir) varies from unusual to very unusual.

## ROTATION

#### 90° rotation to the left or right

These buttons let you switch a panorama when the corresponding group pictures do not have a good landscape/portrait orientation.
Note that even if the panorama seems too aligned, rotating it 90 degrees can cause a misalignment in the pictures. Therefore, we strongly advise you to click on the Auto Level tool after rotation

#### Modify Yaw Pitch Roll

This tool lets you make changes to the panorama with the 90° right rotation, 90° left rotation, positioning of the viewpoint, Automatic Level and vertical lines tools.
The angle of rotation must be expressed in degrees; the successive changes are added to each other (a rotation of -10° is cancelled when it follows a 10° rotation).

 Yaw Horizontal shift (towards the right for a positive value). Pitch Vertical shift (towards the bottom for a positive value). Roll Rotation around a central point (clockwise for a positive value). The panorama’s central point is indicated by the intersection of the two grey lines of the grid, one is horizontal and the other is vertical. Apply Click on this button to confirm the modifications or push the enter button. The preview of the panorama then adjusts according to the constraints you have to define. You can undo changes after validation using the history. Cancel Click this button to ignore the changes and return to the previous state.

## POINT OF VIEW, HORIZON AND VERTICAL LINES

#### Vanishing point

The vanishing point tool will change the panorama’s point of view; this implies a visual change of the vanishing points due to a type of projection selected previously.
Before displaying the preview, Autopano has already made an estimate on the center of the skyline.
This said, it is better to be aware that Autopano totally ignores what has been photography and that you are in a better position to choose.

This tool centers the image where you click. In other words, it defines another point of view that the point of view of origin, which has a dual effect:

• Drages the point of view's vertical axis (the vertical grey line will be the reference point).
• Drags the point of view's horizontal axis (the horizontal grey line will be the reference point).

With the rectilinear projection, the vanishing points are affected by the dragging of the point of view’s center (Perspective transformation equivalent to that can be seen in a camera's viewfinder when you rotate it to the left or right).
The point of view’s horizon line should, in principle, be at the same height as the camera during shooting, except for when taking low angle shots (vanishing point towards the top) or a view from above (vanishing point towards the bottom).

 By checking the "Center Point tool stays activated after use" box, you can try several points of view without having to reactivate the tool. Use the history to undo the changes.

#### Automatic horizon

Often, Autopano automatically creates a panorama where everything is level and thus the "before" and "after" difference is not seen!
The tools described above were used to incline or vertically centre the panorama and on the contrary, the Automatic level effect becomes visible.

Moreover, Autopano does not always straighten the panorama:

• If the camera’s rotation axis was not vertical when passing from one picture to the other (shooting without a tripod or the tripod axis or the pan head was not aligned).
• If all the pictures were taken from the same side (this should not happen with a panoramic head, in the case of a tripod this is different than the previous setting).

In these two cases, the Vertical lines tool needs to be used to put everything into place.

#### Vertical lines

This tool lets you straighten a panorama by tracing vertical lines in the panorama’s editing area:

Trace the lines (symbolized by blue strokes) from top to bottom, where vertical lines are found in the photographed item (the edges of buildings, doors and windows, corners in the walls, furniture).
The yellow dotted line (which is displayed at the same time as the blue line) is used as a reference mark to straighten the horizons. This is very useful if your panorama does not have vertical lines (landscapes, nature, etc.).
Only the blue lines appear with the rectilinear projection. With the other 3 types of projection, the doted yellow line appears each time a blue line is traced.

To change the orientation or length of a line: click on it and use the red boxes found at the ends of the lines. To delete a line: click on it and press the delete key.

Two or three lines are enough, especially if they are spaced from each other. It is possible to place more if they are reliable. Autopano will find the best compromise based on your instructions and the links between the pictures.

Tracing one single line can make a panorama rotate quickly: the traced line will become a perfect vertical. If the blue line is horizontally traced, the panorama will make a quarter turn and if the line is traced from the bottom to the top it will make a half turn.

 Using the Horizontal line will straighten a tilted skyline. This works the same way as the Vertical line tool: just trace a stroke on the line that should be horizontal. This tool is only available when using the rectilinear projection mode. Apply Click on this button to confirm the modifications or push the enter button. The preview of the panorama then adjusts according to the constraints you have to define. You can undo changes after validation using the historical. Cancel Click this button to ignore the changes and return to the previous state.

## FRAMING

#### Crop

This tool lets you choose the frame of the panorama. Its original position automatically corresponds to the maximum rectangular area of the current panorama.
The default framing is automatic; no part of the selection is left blank.

To resize the frame, use the small squares around the frame. When pressing the Ctrl key, the resizing is done starting from the center of the frame. To move the frame, place the mouse cursor inside the frame. The cursor turns into a hand. To rotate the frame, place the mouse cursor outside of the frame. The cursor turns into a rotation arrow.

 Crop zone : Lets you precisely change the framing: Theta: corresponds to the width of the frame. Phi: corresponds to the height of the frame. Rotation: lets you rotate an angle of the frame. Full sphere: lets you frame the panorama in case there is complete spherical part of the panorama. Ratio: Lets you define a framing ratio (useful to define a framing for printing or to have an identical ratio for a series of panoramic images). Style: Normal: (default) Defines a free frame (without height and width constraints). Ratio: Forces the frame according to the height and width values. Width: Defines the ratio width. Height: Defines the ratio height. Swap: Lets you invert the height and width values. Apply Click on this button to confirm the modifications or push the enter button. The preview of the panorama then adjusts according to the constraints you have to define. You can undo changes after validation using the history. Cancel Click this button to ignore the changes and return to the previous state.

#### Autofit

This tool produces an effect that is the opposite of that obtained with the Crop tool: the panorama is framed with a rectangle that is as large as necessary so that nothing remains outside the frame.