2013年4月17日星期三

Panoramic photography - with Panoweaver

Panoramic photography
Panoramic photography - Type of panoramic photos
360 panoramic photography - Create 360*180 degree photos
Workflow of Panoramic photography with fisheye lens and Panohead
1. Assemble the Equipment
2. Preset Camera
3. Adjust the exposure mode
4. Adjust image size and quality
5. Adjust Camera
6. Shooting Fisheye Photo
The key of creating 360*180 degree panoramic photographs - Panorama Software

What is panoramic photography?

Panoramic photography maybe has many definitions, but for us, it is a format of photography that captures great wide-angle photos. This wide-angle we are talking about is not general wide-angle, it should be greater than human's field of view(about 75 degree). It is a consensus which was developed by the people who create panorama photos. In fact there is no formal definition to tell us this is wide-angle and that is panorama.
Note-What is panorama?
In the 19th century, the time when people invented panoramic photography, stitching pictures is the only way to get a panorama. In 1851 Martin Behrmanx took some photos on Rincon Hill in San Francisco. It is said that this photo initially had eleven plates. From this picture we can see Rincon Hill stitched a few pictures together, then get this panoramic photo.
panoramic photography
At that time, panoramic photos often meant wide angle and wide aspect ratio(like the picture above). This situation has continued to the era of digital photography.

Panoramic photography - Type of panoramic photos

With the emergence of image-processing software, people began to use digital pictures to create panoramic photos. For example, they use One-shot, the optic for capturing seamless 360-degree images in an instant, or take multiple pictures to stitch.
With one-shot, we can get a 360 degree panorama on the horizon quickly, but because of the limit on the vertical, we can not see the top and bottom from one-shot panoramic photos.
panoramic photography
With standard lens or wide-angle lens, we can take multiple digital pictures to stitch a panorama photo, which has wide angle on horizon and vertical, and this wide angle often is less than 180 degree.
panorama photo
Although these types of panoramas can meet some of our needs, the pursuit of photographers can never be stopped. Now 360*180 degree panoramic photography is a very important part of photography. 360*180 degree field of view allows us to see every corner of a place from its panorama. And with the panorama viewer we can get the effect of virtual reality on computers, which gives us more sense of immersion than plane panoramic pictures.

360 panoramic photography - Create 360*180 degree photos

Creating a 360*180 degree panoramic photo is not easy, unless you have a strong panorama-stitching software and some special equipment(fisheye lens and pano-head).
Limitations on standard lens or wide-angle lens
If you use standard lens or wide-angle lens to take multiple pictures, you need to take dozens of pictures in order to create a 360*180 degree panorama. As the FOV of standard lens and wide-angle is limited, taking numerous picures is inevitable. Such great amount of work takes much time and also makes the shooting quite complicated.
panoramic photography
How can we take the minimum of pictures to get a panoramic photograph?
The solution is to use fisheye lens. Fisheye lens has ultra-wide-angle and has a 180 degree angle of view on the diagonal line. In this way, only 4-8 photos are needed for a 360*180 degree panorama.
panoramic photography

Workflow of Panoramic photography with fisheye lens and Panohead

The main panoramic photography equipment are: Digital camera (abbreviation as DC),Fisheye lens, Pano Head and Tripod.

1. Assemble the Equipment

Pano Head is essential for panoramic photography, which can be classified as two types: lens specific pano head and non-lens specific pano head. The former is applied to certain lens and cameras, which is simple to install since there will be no need locating a nodal point. The latter can be used to all the lenses & cameras, however you need to locate the nodal point yourself. The following chapter will give you instruction on assembling different equipment.
Tips:How to locate camera nodal point with JTS pano head?

2. Preset Camera

Presetting once is enough when shooting many images for different scenes.
Set as fisheye mode (Optional)
Note: DSLR camera need not adjust this.
For Nikon Coolpix series and some cameras with no fisheye mode, you need to set manually before shooting. Here is a brief instruction.
Camera ModelInstruction on selecting lens
Nikon Coolpix 5400 /8700/8400Go to the menu and select Lens>Fisheye
Nikon Coolpix 4500/995Go to the menu and select Lens>Fisheye1 for full circular fisheye shooting; OR Lens>Fisheye2 for full frame fisheye shooting.
Nikon Coolpix 5700 and the DC with no fisheye modeMacro mode :zoom locked at wide angle
Exposure metering: Center-Weighted
Flash modes: Flash Cancel

3. Adjust the exposure mode

The word "photography" derives from the Greek and means, literally, "light writing." Lighting is mainly controlled by aperture and shutter speed. The shooting modes available in most digital cameras range from Auto mode, Scene mode, Programmed auto, Shutter-Priority auto, Aperture-priority auto and Manual mode. The latter four modes act on panorama shooting and so does the Panorama Assist Mode.
Note: Please DO NOT use Auto mode for panorama shooting.

If you are experienced in photography, Manual mode is recommended to choose appropriate aperture and shutter speed according to the environmental light.
If you are a green hand, a usual advice is to choose Aperture priority auto mode. Set a larger F value to get a small aperture so that a deeper "Depth of Field" (DOV) is achieved with a much wider scope of clear area in the image. (The larger F value is, the smaller the aperture is.) For example, F5.0 or F6.0 is better than the default F2.5 or F3.3.
Please pay attention if the environmental light is a little dark. Small aperture may result in longer exposure time, i.e. shutter speed. The reason is the flash light doesn't take effect with fisheye lens since fisheye lens covers a much wider FOV than traditional camera lens. Over 1/4 of the shutter speed may bring obvious noise in the image. So you have to find a proper value to balance the aperture and shutter speed.
Note: A stable tripod is extremely important if the exposure time is very long.

4. Adjust image size and quality

The fisheye image resolution and quality determine to a great extent the panorama quality. The better the fisheye image is, the better the stitched panorama is. Of course it occupies more space. So it is recommended to use the largest resolution available when shooting.
As to the image quality, "FINE" is all right. "High" can be applied for acquiring high quality images. If selecting High, the image size is about 10M so a bigger memory card is required. The original file format is TIFF. Camera Raw Image is also available in some cameras.

5. Adjust Camera

Redo the following steps to adjust the camera every time shooting a different scene.
Adjust white balance
White balance is a name given to a system of color correction to deal with differing lighting conditions. Normally our eyes compensate for different lighting conditions, but when taking pictures with a digital camera the camera has to find the "white point" (the assumption that a white object must appear white) to correct other colors cast by the same light. Inappropriate white balance may bring about more blue or more red than the original color.
General users can select Auto on White Balance menu. The professionals may select "White Bal Preset" or self-adjust the white balance.
Adjust the aperture
In panorama photography, greater DOV (Depth of Field) helps to acquire a clear image in a wider range. Therefore it is important to use a smaller aperture in panorama photography than in ordinary photography. To decreases the aperture, please increase the F to a value as high as F5.0 or F6.0.
Adjust the shutter speed
As mentioned in previous chapter, over 1/4 of the shutter speed may bring obvious noise in the image. Therefore if the shutter speed is more than 1/4 second under Aperture priority auto mode, we suggest you switch to Manual mode.
Adjust the exposure compensation
After setting the aperture and shutter speed, if the image in the monitor is too dark, choose a positive value for exposure compensation. Similarly, if the image in the monitor is too bright, raise exposure compensation until the desired effect is achieved.
Note: When shooting two or three fisheye images of the same scene, do not change the exposure compensation value. Otherwise it will cause distinct seam in the stitched panorama. The following image is an example. In addition, do not raise the exposure compensation to a much higher value. It may cause over exposure so that the stitched panorama from fisheye images will have a distinct "blue seam".

Note: The above panorama image is stitched from images shot with different exposure compensation value. There are obvious image brightness differences in the two fisheye images' area.
Set AE Lock (Optional)
Note: DSLR camera need not adjust this.
Setting AE Lock (Automatic Exposure Lock) is one of the most significant steps in panoramic photography. AE lock is the ability to lock the cameras calculated exposure settings (aperture, shutter speed, and sensitivity) over a series of images. When stitching images together each image should have the same exposure. The flash is turned off while AE Lock is in effect.

Note: Above panoramic image is stitched from images shooting without using AE Lock. There are obvious image brightness difference in the two fisheye images' area and two obvious blue seams resulting from difference exposure value of two fisheye images.
After setting the proper aperture and exposure compensation, turn to AE Lock > ON in the menu.

6. Shooting Fisheye Photo:

Please take the following steps strictly in panoramic photography.
1. Shoot the first fisheye image
Place the point of interest in the center of the viewfinder then half press the shutter to focus.
2. Shoot the other consecutive fisheye image
To guarantee the tripod stableness, hold it with one hand. Turn the pano head gently with the other hand. Rotate appropriate degrees and take the images around 360 degrees.
Note: It is suggested the images be shot clockwise, otherwise, you may have to reverse the sequence when loading images in Panoweaver.
3. Shoot top/bottom fisheye (optional)
Please shoot Top/Bottom fisheye image on the last rotation. For 4 fisheye, please rotate pano head up and down to shoot at the 4th location. For 6 fisheye, please shoot up and down at the 6th location. You should stay with the last rotation. Shooting in some other location will cause an incorrect stitching.
4. Shooting another scene
After shooting a scene, cover the fisheye lens cap. Move all the equipment to the other scene you want to shoot.
Note: Turn the "AE Lock Off" otherwise the shutter speed and aperture are locked. The shooting procedure is the same as stated above.
5. Import the images to the computer
After Finishing, import the fisheye images to computer through DC or card reader. If the original image has much noise or is not sharp enough, it can be retouched in any image editing application such as Photoshop, Fireworks etc.

The key of creating 360*180 degree panoramic photographs - Panorama Software

A powerful panorama-stitching program, a fisheye lens and a pano-head are all indispensable elements in the panoramic photography process, but the key element in creating 360*180 degree panorama photos is panorama software, because a perfect panoramic photo can only be created by a powerful panorama software.

Panorama Software - Panoweaver

Panoweaver is professional panorama Software to stitch any photos to 360 degree panorama. Within minutes, you can get high quality panoramic image and full screen panoramic tours in Flash, QuickTime and Java player. Standard digital photos and wide-angle photos in single line and mutiple lines, and fisheye photos can all be stitched into 360 panoramas.

Source: www.easypano.com

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