Nikon D3 has a
12.0MP Full frame (36 x 23.9 mm ) sized CMOS sensor and features Expeed processor. On the other hand, Panasonic AW-UB50 has a
24.2MP Full frame (35.6 x 23.8mm ) sized CMOS sensor .
Panasonic AW-UB50's sensor provides 12.2MP more than Nikon D3's sensor, which gives a significant advantage in real life. You can print your images larger or crop more freely.
On the other hand, please keep in mind that Max sensor resolution is not the only determinant of resolving power. Factors such as the optical elements, low pass filter, pixel size and sensor technology also affects the final resolution of the captured image.
Below you can see the D3 and AW-UB50 sensor size comparison.
Sensor Size and Resolution Comparison image of Nikon D3 and Panasonic AW-UB50 Cameras
Nikon D3 and Panasonic AW-UB50 have almost the same sensor size, so neither of them has any significant advantage over the other in terms of providing control over depth of field when used with the same focal length and aperture.
Sensor size sets the circle of confusion, so it drives how much depth of field each
of these bodies gives you at a given aperture. You can calculate it exactly for the
Nikon D3
or the
Panasonic AW-UB50 ,
including hyperfocal distance.