![]() ![]() VPC is most commonly used in the context of cloud infrastructure as a service. ![]() With the introduction of the described isolation levels, an organization using this service is in effect working on a ' virtually private' cloud (that is, as if the cloud infrastructure is not shared with other users), and hence the name VPC. ![]() In a VPC, the previously described mechanism, providing isolation within the cloud, is accompanied with a virtual private network (VPN) function (again, allocated per VPC user) that secures, by means of authentication and encryption, the remote access of the organization to its VPC resources. The isolation between one VPC user and all other users of the same cloud (other VPC users as well as other public cloud users) is achieved normally through allocation of a private IP subnet and a virtual communication construct (such as a VLAN or a set of encrypted communication channels) per user. ![]() Such an image will be magnified if the position of the object is within twice the focal length, or else the image will be reduced if the object is further than twice the focal length.Pool of shared resources allocated within a public cloud environmentĪ virtual private cloud (VPC) is an on-demand configurable pool of shared resources allocated within a public cloud environment, providing a certain level of isolation between the different organizations (denoted as users hereafter) using the resources. In contrast, an object placed in front of a converging lens or concave mirror at a position beyond the focal length produces a real image. A converging lens (one that is thicker in the middle than at the edges) or a concave mirror is also capable of producing a virtual image if the object is within the focal length. Such an image is reduced in size when compared to the original object. A diverging lens (one that is thicker at the edges than the middle) or a convex mirror forms a virtual image.The image in a plane mirror is not magnified (that is, the image is the same size as the object) and appears to be as far behind the mirror as the object is in front of the mirror. Although the rays of light seem to come from behind the mirror, light from the source only exists in front of the mirror. A plane mirror forms a virtual image positioned behind the mirror.A real image can be projected onto a diffusely reflecting screen so people can see the image (the image on the screen plays as an object to be imaged by human eyes). In contrast, a real image can be projected on the screen as it is formed by rays that converge on a real location. In diagrams of optical systems, virtual rays (forming virtual images) are conventionally represented by dotted lines, to contrast with the solid lines of real rays.īecause the rays never really converge, a virtual image cannot be projected onto a screen by putting it at the location of the virtual image. In other words, a virtual image is found by tracing real rays that emerge from an optical device ( lens, mirror, or some combination) backward to perceived or apparent origins of ray divergences. A real image is the collection of focus points made by converging rays, while a virtual image is the collection of focus points made by extensions of diverging rays. In optics, an image is defined as the collection of focus points of light rays coming from an object. Thus, an image cannot be seen by placing a screen at the position of the virtual image. It can be seen on the right for the top diagram and on the left for the bottom diagram that the light rays appear to emanate from the virtual image but do not actually exist at the position of the virtual image. Solid blue lines indicate (real) light rays. In both diagrams, f is the focal point, O is the object and I is the virtual image, shown in grey. Bottom: The formation of a virtual image using a convex mirror. Top: The formation of a virtual image using a diverging lens. For digital-media objects, see Virtual artifact. For the representation of objects in computers, see Virtualization. ![]()
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