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We have previously established, from a carbon star survey, that the LocalGroup dwarf irregular galaxy NGC 6822 is much larger than its central brightcore.  Four MegaCam fields are acquired to survey a 2$^\circ\times$ 2$^\circ$ areacentred on NGC 6822 to fully determine its extent and map its stellarpopulations. Photometry of over one million stars is obtained in the SDSS g$'$,r$'$, i$'$ to three magnitudes below the TRGB. RGB stars, selected from theirmagnitudes and colours, are used to map the NGC 6822 stellar distribution up toa distance of 60 arcmin. We map the reddening over the whole area. We establishthat the stellar outer structure of NGC 6822 is elliptical in shape, with$\epsilon=0.36$ and a major-axis PA = 65$^\circ$, contrasting with theorientation of the HI disk. The density enhancement can be seen up to asemi-major axis of 36$'$ making NGC 6822 as big as the Small Magellanic Cloud.We fit two exponentials to the surface density profile of the spheroid, andidentify a bulge with a scale length of 3.85$'$ and an outer spheroid with ascale length of 10.0$'$. We find intermediate-age C stars up to $\sim$ 40$'$while demonstrating that the SDSS filters are unsuitable to identifyextragalactic C stars. NGC 6822 is a unique Local Group galaxy with shape andstructure suggesting a polar ring configuration. Radial velocities of carbonstars have indeed demonstrated that there are two kinematical systems in NGC6822.Comment: A&A in pres

Photometric survey of the polar ring galaxy NGC 6822