It depends on the purpose of the surveillance camera. For basic security purposes, such as monitoring who enters a building or capturing images in low light conditions, 2 to 4 megapixels should be sufficient. However, if you need to capture detailed images with sharp focus and clarity (such as license plates), then 8-10 megapixels is recommended. Additionally, depending on the distance from which you will be viewing your footage, higher resolution cameras may be necessary for better recognition of objects within range.