The dmesg output of my DS-2CD2032 reports "MT9T002 sensor ID is 0x2604". According to the datasheet, this is the former name of the Aptina Imaging AR0330.
Rev D. 11/1/10 "Changed part number from MT9T002 to AC0330"
Rev E. 12/17/10 "Changed part number from AC0330 to AR0330"
The sensor has a raw pixel array of 2304Hx1536V but basically operates in two modes (from which other resolutions can be derived):
2304x1296 at 30 fps (16:9 sHD)
2048x1536 at 25 fps (4:3, but -20% for EIS)
So it looks like the Hik FOV change from 1080P to 3MP could just be a function of which pixels are active + cropping and not due to any resampling on their part.
that said, it would be nice to have access to the full 2048x1536 mode as well since I generally don't go off-roading with my security camera
https://www.aptina.com/products/image_sensors/ar0330/.