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2020-05-16

Fisheye vs Equirectangular

This is a quick guide explaining the difference between dual fisheye images and properly stitched equirectangular panoramas. It is a common problem encountered by many 360 camera users.

Most of the 360 cameras on the market are "dual lens" devices. This means they have two lenses, one on the front and one on the back.

This includes all Ricoh Theta models, Insta360 ONE X and R, GoPRO Max, Kandao Qoocam, Mi Sphere, Samsung Gear360 and many others.

Dual fisheye images

When these cameras take a shot, it is stored in the camera memory as a file with two fisheye images next to each other. It looks like the picture below, though sometimes the layout can be top/down instead of side by side:

Dual fisheye format

Problem with fisheye

The problem is that fisheye images are often in JPG format and it's easy to confuse them for correct panoramas.

If this happens and you upload those images to Kuula, you'll see a wide, ugly stitching line and a shape reminding of an aircraft propeller when you look up or down:

Helix-like distortion in fisheye images

Before you can use those images to create virtual tours and share them on the web, you'll need to covert them to the proper equirectangular panorama format.

Equirectangular panoramas

The same image converted to equirectangular looks like on the illustration below. The main difference is that the image covers the entire area and there are no black parts around the edges. You can also no longer distinguish two separate parts. It's all one big image.

Equirectangular panorama

How to convert fisheye to equirectangular?

The conversion is done in the software that comes with your camera. When you save the images from the camera to the camera's mobile app, the conversion is done automatically. In this case, chances are you will never come across the fisheye format.

However, if you connect the camera to your PC or laptop via USB and copy the images to your local drive, you will need to convert them manually in software provided by the camera producer.

Below is a list of panorama editing programs provided by the producers of popuplar spherical cameras:

You camera is not listed?

If you came across the fisheye format issue and you did not find your camera on the list above, let us know.

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