Accuracy of geometrical on-screen measurement performed by Inspectis Software depends mainly on following parameters.
Magnification. The higher magnification is, the more accurate measurement results can be. Higher magnification, however means less Field of View, why you have to select highest possible magnification (or zoom factor) which provides required Field of View.
Image Distortion. Distortionis a deviation from rectilinear projection. Straight lines of an object don´t remain straight in a distorted image, why measurement accuracy of the object will be affected. Distortion must be controlled in optical systems used for performing geometrical measurements.
Calibration. Accuracy of Calibration procedure you perform in software as well as accuracy of the Calibration Scale you use is directly reflected in the accuracy of your Measurements. A digital picture is a matrix of Pixels (i. e. 1920×1080 pixels if Full HD) with a certain Pixel size. When you calibrate a Magnification in Inspectis, the software calculates Pixel-to-Millimeter ratio for that specific Magnification. This ratio is then used for translating the number of Pixels to Millimeter or Micrometer when you perform geometrical measurements. You can see Pixel-to-Millimeter ratio on status bar of Inspectis user interface displayed as “Calibrated Pixel Size”.
Image quality, Resolution Power. Higher resolution power, means larger number of image sensor pixels but also ability of the optical system (lens) to resolve detail in the object that is being imaged on image sensor. If two points that are close to each other are resolved by optical system and imaged on more than two adjacent pixels, you can measure distance between those points with a accuracy of one (1) pixel.
Image Focus. A sharp picture is required for performing accurate geometrical measurements. Sharp edge of an object which is not in focus is imaged as a blurred edge on more pixels. This is equivalent to having lower Resolution Power.
Accuracy of Operator. Manual measurement of – for example- a distance on a picture is highly reliant on how accurately the start and end points of the measurement line are selected