Dewarp For Fisheye Cameras

Fisheye lens is an ultra-wide-angle lens that produces a wide panoramic image at the cost of strong visual distortion. Usually, devices with such lenses capture a 360-degree geometrically distorted image and projects it as a circle within the image frame. Fisheye lens can be either built-in by design or purchased separately and installed on your desired camera. Macula dewarp feature allows to correct the perspective and obtain several "normal" views from a single distorted fisheye picture.

In order to access dewarp settings via Macula Console, open the Configuration section and choose Channels from the menu on the left. Find the channel you wish to dewarp in the list (use Search or filters, if necessary) and double-click it in order to open it for editing (alternatively, use the Edit button on the upper panel to open the dialog box), then switch to the Dewarp tab.

Please note that the location of dewarp settings has changed starting from the product version 1.5.0. For previous software versions, the corresponding settings can be found in the general Channel Properties dialog box.

You have the following options here:

• Regular lens: choose this option if you wish to disable the dewarp engine (selected by default)

• Immervision Enables® lens: choose this option if your camera has a Panomorph lens installed (you can check this in the camera specification)

• Fisheye lens: choose this option if your camera has a regular 360-degree view lens

• Fisheye lens (large resolution): dewarp engine optimised for image resolutions of 6MP+

If your fisheye image has a resolution of 6 megapixels or higher, it is better to use the last option in the drop-down list - fisheye lens optimised for high resolutions. This mode will provide smoother DPTZ experience with the dewarped image. If your graphics card supports OpenCL version 1.2 or higher, this dewarp driver will use GPU (you can check this in your video driver properties, or request info from the video card manufacturer). Otherwise, more CPU time will be required, compared to the basic fisheye mode. We recommend that you do not use this driver for smaller resolutions, as it may use more CPU yet there will be no difference for the user.

For devices having a Panomoph lens, choose the lens model from the drop-down list - you can find this information in your camera specification or request it from the device manufacturer. You do not need to define any parameters manually in this case; rather, you only need to choose your camera mounting position, and the dewarp engine will automatically produce a correct dewarping result.

Note that the dewarp engine will fail to operate if you choose a wrong Panomorph lens model. Check with your camera documentation and manufacturer for the precise lens model information.

For a regular fisheye lens, you are requested to define the fisheye sphere size and camera position by using the overlay controls and settings on the right side:

• Hemisphere diameter: click and drag any of the small pink circles on the overlay sphere to change its size and align it with the actual fisheye sphere in the picture

• Horizontal and vertical centre: automatically positioned in the picture centre, to change it click and drag the small pink circle inside the sphere

• Mounting direction: select camera mounting position from the drop-down list (wall/ceiling/floor)

For your convenience, the defined parameters are also displayed in the numeric form on the right side of the dialog box. Use the button below the preview to reset all dewarp settings to the default ones.

In case you change the stream resolution at some point, its aspect ratio may also be changed and this will affect dewarp operation. Therefore, check the dewarp settings after changing the resolution and adjust the parameters, if necessary.

Note that all dimensions are given not in pixels but in reference to the video stream size, therefore, relative values are used instead of absolute ones.

When finished, click OK to save the changes and close this dialog box and return to the general channel configuration. Dewarp results will immediately become available in the Macula Monitor application; you can find the details on usage in the corresponding section of the Macula Monitor documentation.