Ricoh G900 has a 20.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized BSI-CMOS sensor . On the other hand, Olympus VH-515 has a 12.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized BSI-CMOS sensor and features TruePic III+ processor.
Ricoh G900's sensor provides 8MP more than Olympus VH-515'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 G900 and VH-515 sensor size comparison.
![Ricoh G900 vs Olympus VH-515 Sensor Size Comparison]()
Sensor Size and Resolution Comparison image of Ricoh G900 and Olympus VH-515 Cameras
Ricoh G900 and Olympus VH-515 have sensor sizes so they will provide same level of control over the depth of field when used with same focal length and aperture.