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Globe Flattening

Aim

The aim of the program is to extract a spherical surface and transform it into a flat rectangle.

Input

The image of a globe.

Output

A flattened image of the globe.

Hints

An image presenting a globe can be flattened in several ways, but the easiest one is to think of the globe as a sphere and consider one of the Image Spatial Transforms Maps filters to create a proper map and then display it as an image.

Solution (AVS)

Add LoadImage filter.
Add CreateSphereMap filter.
- Connect outImage from previous filter with inImageFormat of the current one.
- Click on the inSphereRectangle filter and then specify the area to be flattened by clicking inSphereRectangle in Properties window:
- Set inSphereRadiusCorrection to 60. It determines how many pixels the sphere radius is larger than the visible circle radius.
- Set inMargin to 260 to display only remapped area without unnecessary margin. Margin is the width of the sphere extreme points zone excluded from spatial map.
Add RemapImage filter.
- Connect outImage from LoadImage filter with inImage of the current one.
- Connect outSpatialMap from the previous filter with inSpatialMap of the current one.

Macrofilter Main

Used Filters

Icon	Name	Description
	CreateSphereMap	Inspection of the surface of balls and other spherical objects. The result is used by RemapImage.
	LoadImage	Loads a single image from a file.
	RemapImage	Fast (precomputed) image transformations, especially for view undistortion or object geometry correction (e.g. pos recognition of labels on cylindrical bottles).