Both Panasonic G3 and Panasonic G6 have Four Thirds sized 16.0 MP resolution sensors so sensor size and resolution is not a differentiator between these two cameras.
Below you can see the G3 and G6 sensor size comparison.
Sensor Size and Resolution Comparison image of Panasonic G3 and Panasonic G6 Cameras
Panasonic G3 and Panasonic G6 have the same sensor sizes so they will provide same level of control over the depth of field when used with same focal length and aperture.
DxOMark Sensor Scores
DxOMark is a benchmark that scientifically assesses image quality of camera sensors. It scores camera sensors for color depth (DXO Portrait), dynamic range (DXO Landscape) and low-light sensitivity (DXO Sports), and also gives them an overall score. Panasonic G3 and Panasonic G6 sensors have been tested by DxO and the results show that G6 has a better overall score of 61, 5 points higher compared to G3's score of 56.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Panasonic G3
56
21.0 bits
10.6 Evs
667 ISO
Panasonic G6
61
21.3 bits
11.5 Evs
639 ISO
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
Panasonic G3
or the
Panasonic G6 ,
including hyperfocal distance.