## How Many PixelsLet's compute the number of pixels using the following assumptions and our geometries from the previous page: inner diameter = 36 mm outer diameter = 120 mm radial resolution = 0.1 um tangential resolution = 0.1 um (worst case) In the radial direction (let's call this Y) our formula is: Outer In the tangential direction we have to take our longest path (2π Outer 2π Outer Now, if we multiple these two numbers we'll get the total number of pixels. And its pretty big. 4.2E Converting into GB of memory required to hold these pixels gives us:
Oversampling?
When mastering engineers say that this approach leads to oversampling what they mean is that there are more pixels than really needed in the tangential direction for all but the outer cylinder or strip. As we computed earlier, the pixels for the outer cylinder strip are spaced at 0.1 um because there are 3.7 million spread over 377 mm. But for the inner cylinder there are still 3.7 million pixels but they are spread over 113 mm so they are only spaced 0.03 um apart. |