Panoramic Photography

Producing the original source photography in order to create a panoramic flying site is quite involved, and requires you to take a series of overlapping images forming a complete 360x180° sphere. This operation is most effectively carried out by using a dedicated panoramic mount, but it is possible to get some fairly reasonable results using a home-made mount.

Equipment

 

There are several steps you can take before actually taking the shots to ensure a better result:

Position and height
Make sure that you are positioning your camera in the place where you would actually stand when piloting your aircraft. If you position your camera in an incorrect place there is no way of repositioning after the shots have been taken, so take special care that you have chosen the optimal place for flying. You must also raise your camera to a reasonable height on the tripod, so that when the image is formed the user will not feel as though he or she is higher or lower than is a natural "head height".

Light and shadow
One important thing to take into account is that you will usually only want to create a single panorama of your chosen site, so you will be aiming for the most optimal lighting conditions possible. Do not take your pictures when the sun is in a position which makes normal flight difficult, at sunrise or sunset (unless you especially wish these conditions), on a very overcast day, or in any other kind of conditions which may effect the final images in a negative way.

Conditions
When taking a series of photographs which require stitching together, you will want a minimum of motion between the individual shots. On windy days there is often a great amount of cloud motion, so it is often best to take panoramas on relatively calm days - making the stitching process easier on cloudy skies. Equally, it is often good practice to make sure that there is always some kind of cloud cover, which gives the pilot a frame of reference when flying: completely clear skies can reduce the effect of motion when there is nothing else in view when flying.

When you have decided a position to take your photographs and you think the lighting and conditions are optimal for a good result, you are ready to take the pictures which will be stitched together to create your digital flying site.

To create a spherical 360x180-degree panorama, you will be taking several rows of pictures - each a 360-degree "cylinder" - with each row looking at a higher or lower angle than the previous, until the complete visible sphere has been recorded.

Focal length and image quality
The number of images you need to take for each row/inclination depends on the focal length you have set the camera to. This is typically altered by changing the lens or zooming in or out. A smaller focal length will record a larger area per picture, and so a complete row can be made up of less pictures. The drawbacks to using a smaller focal length are as follows:

A reasonable compromise between quality and number of pictures is to take around 12 images per row. This roughly equates to a focal length of 18mm and includes sufficient overlap for stitching. 12 images also conveniently means that each picture is 30° apart, making the use of a protractor or piece of marked card to measure the needed change between images is trivial.

Please note that you will still need a very high-resolution camera to gain the required final image quality - we recommend an absolute minimum of 8/10 Megapixels upwards.

White balance and exposure
As you move your camera around the panorama, the amount of brightness will change depending on the sun/light's position. Most cameras will automatically alter the exposure and white balance to gain optimal results depending on the amount of light. This can make stitching the individual photographs together evenly more difficult as the tone, brightness and contrast will be changing.

A good practice is to locate the "half-way" point between the brightest area (usually pointing directly at the light-source), and the darkest (usually the opposite direction). Point the camera at this area and manually set your white-balance and exposure settings. This should give you a fairly good range between very light and dark, without letting the camera change the settings per picture, making it easier to create a more evenly coloured/toned panoramic image.

Unfortunately, the range of lighting conditions may be too large to take your panorama with a single exposure setting. In this case we recommend manually varying the exposure between shots, and altering them only very slightly. In the worst-case scenario, an automatic exposure mode can be used, and the images can be post-processed to create a reasonable final image.

Final steps
Once you are happy with the white-balance and exposure and know the number of pictures you should be taking, align the camera with a known landmark. This will be your first picture, and provides an obvious point from which to start each row. The first row will be the horizontal "horizon" row, and will form the basis for the entire panorama.

When taking shots, make sure you do not knock the tripod or mount, as this can change the alignment and negatively affect the end result. A good method is to use an infra-red remote to release the shutter instead of trying to press the button - which may be at an awkward to reach angle.

Remember, from the instant you take your first shot to the moment the final shot is taken your environment will be changing. Try to work methodically, carefully but quickly to minimize the amount of exterior changes which occur whilst you take the images.

Once the horizon row has been recorded successfully (making sure each image has at least 20% overlap with the one before) you will need to take the next inclination. Usually the camera is raised one division higher to begin recording the sky, as the sky is the part of the image most likely to change fastest.

When each row is taken, the camera's inclination is raised until the camera is facing fully upward, at which point a single shot is taken to fill any blank sections. Once done, the camera is returned to the horizon line, and angled down one division to repeat the process for the ground.

Once all images have been taken, the tripod may be removed and the camera disconnected from the mount to take a single shot roughly from the correct position in order to fill the lowest ground angle in post-processing.

When all of the images are safely transferred to a computer system, we highly recommend taking a CD-ROM backup, as it would be very time-consuming and difficult to retake them - and the exact lighting conditions may be very hard (if not impossible) to recreate.

The images should be in JPEG (.jpg) format, at the lowest compression (highest quality) level, and zipped together in an archive named with the flying site identification/name.

Along with the images, we would also require:

- Plan of the flying site, either as a rough sketch or a satellite image from a source such as Google Earth. On this plan should be marked the areas for helicopter and airplane flying, and the recommended starting positions for both types of aircraft, including the correct runway (if applicable) direction.

When assembled, you can send the materials to us in the following ways:

If you have created you panoramic source materials and are ready to submit them, require any further assistance or a more detailed explanation of any part of this document, please contact us at scenery@phoenix-sim.com.