Why is the surveillance camera in the dark behind the building, and there is nothing in the sun?

This is because the tolerance of the camera CCD is not enough, the exposure is normal when the light is sufficient, and the ISO enhanced exposure can be automatically adjusted when the light is dim. However, when the picture has both bright and dark parts, it will lead to inaccurate exposure, which is characterized by overexposure of bright parts and underexposure of dark parts.

Using HDR camera can provide images with high dynamic range, thus alleviating the problem of exposure deviation.