PanGazer logo PanGazer – overlays


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Image geography



Making panoramic images

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The gnomonic projection


PanGazer uses ‘status’ text fields to show camera settings, etc. (see the settings page). In addition, it can overlay data on the image that are directly related to the image itself rather than being simply numerical values. Currently two overlays are available:

  • Compass points – if the bearing of the image is known, this overlays points of the compass across the top of the view to indicate the direction of view

  • Tilt angles – if the horizon of the image is known, this overlays tilt angle values at the left of the view.

If the bearing or horizon is not known you can set it, as described below. Here is a view showing both overlays:

PanGazer screenshot showing overlays

PanGazer screenshot showing overlays

Compass points

PanGazer lets you set where North is for any image. Once North is set PanGazer can show the bearing of the cursor and can also overlay compass points (‘N’, ‘S’, ‘SW’, etc.) to help give a sense of direction, as shown in the screenshot above.

Although drones know where they are and which direction they are pointing when images are captured (and often record those data), as far as I know no stitching application preserves that information. Therefore, to have compass directions shown correctly (as in the screenshot above) you must identify some point in the image that is due North (True North) of the camera position and then communicate that to PanGazer.

There are two ways to do this:

  1. You can use the image geography dialog box to set (or delete) the bearing of the center of the image – this can be used for any image.

  2. For 360 images and spherical panoramas you can set the direction of North directly; this is quite easy, even if you are unsure where North is in your image:

    Using the starter image as an example, you can use Show location on Satellite map to view the camera (drone) position. One point that is due North of that position is on the road from the church to the larger village (Bejes), about halfway between the church and the first tree beside the road.

    In PanGazer, drag the view (up and to the left) so you can see that point, right-click on it and select Set North on the pop-up menu. You should then see added compass points consistent with those in the screenshot above (North will show at first, and panning until South is visible should correspond with the screenshot). If the position is wrong, just try again (or use the image geography dialog box to adjust or delete the value).

Once North is set, by either method, the compass points will then move appropriately as you change viewpoint and zoom. You can turn them off or on by clicking the Settings → Overlays → Show compass points menu item.

Tilt angles

The tilt of the image is the vertical angle (pitch) of the centre of the image relative to the horizon (positive is above the horizon) with a range from −90 through +90 degrees. For spherical images the position of the horizon is fixed and is calculated from the geometry of the image (the bottom edge of the image is at −90 degrees). For all other images (360 or not) you can set, edit, or delete the horizon position.

To see the tilt angles, first ensure that Settings → Overlays → Show tilt angles is checked (this is off by default).

Like setting North, there are two ways to set the horizon position:

  1. You can use the image geography dialog box to set (or delete) the tilt of the centre of the image.

  2. If the horizon is visible in the image, right-click on it and select Set horizon on the pop-up menu; you should then see the tilt angles at the left of the view. If their position is wrong, just try again (or use the image geography dialog box to adjust or delete the value).


  1. Once the North point or horizon has been set it will be recorded in the image file (in its Exif data) if the image is saved (Ctrl-S or Image → Save image as...). When it is next loaded the bearing and/or horizon of the image is known and compass points and tilt angles will be shown automatically if set to be shown.

  2. Similarly, if you save a view of an image that has its North point and/or horizon set, that saved view will include the settings; see the Saving views page for more details.

  3. The tilt overlay shows the tilt at the (left↔right) centre of the view.

  4. The view bearing is shown at the position that the compass points are displayed (near the top of the view rather than at the top↔bottom centre of the view). This is so the bearings remain static relative to the displayed image as the view is panned left or right.

  5. In the starter image you’ll see a white electricity pylon close to the −90 point if you pitch down far enough; the base of the pylon is also a good point to click on to Set North.

PanGazer and these web pages were written by Mike Cowlishaw; Please send me any corrections, suggestions, etc.
All content © Mike Cowlishaw, 2014–2018, except where marked otherwise. All rights reserved. The pages here, and the PanGazer program, are for non-commercial use only.
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This page was last updated on 2018-12-12 by mfc.