Context : We have previously established , from a carbon star survey , that the Local Group dwarf irregular galaxy NGC 6822 is much larger than its central bright core .

Aims : Four MegaCam fields are acquired to survey a 2 ^ { \circ } \times 2 ^ { \circ } area centred on NGC 6822 to fully determine its extent and map its stellar populations .

Methods : Photometry of over one million stars is obtained in the SDSS g ^ { \prime } , r ^ { \prime } , i ^ { \prime } to three magnitudes below the TRGB .
RGB stars , selected from their magnitudes and colours , are used to map the NGC 6822 stellar distribution up to a distance of 60 arcmin .

Results : We map the reddening over the whole area .
We establish that the stellar outer structure of NGC 6822 is elliptical in shape , with \epsilon = 0.36 and a major-axis PA = 65 ^ { \circ } , contrasting with the orientation of the HI disk .
The density enhancement can be seen up to a semi-major axis of 36 ^ { \prime } making NGC 6822 as big as the Small Magellanic Cloud .
We fit two exponentials to the surface density profile of the spheroid , and identify a bulge with a scale length of 3.85 ^ { \prime } and an outer spheroid with a scale length of 10.0 ^ { \prime } .
We find intermediate-age C stars up to \sim 40 ^ { \prime } while demonstrating that the SDSS filters are unsuitable to identify extragalactic C stars .

Conclusions : NGC 6822 is a unique Local Group galaxy with shape and structure suggesting a polar ring configuration .
Radial velocities of carbon stars have indeed demonstrated that there are two kinematical systems in NGC 6822 .