In good conditions, a pixel density of 250 px/m (80 px/ft) is required for identification purposes. This means that at this resolution, the image quality is sufficient to identify individuals, objects, or other details accurately.
Identification requires the highest level of detail among the common surveillance objectives (detection, observation, recognition, identification). This pixel density allows for clear and precise visual information necessary for identifying specific features such as facial characteristics or license plates.
Reference: Axis Communications. "Axis' pixel density recommendations for surveillance cameras." Axis Communications Pixel Density.