For validating the polarimetric & polarimetric-interferometric SAR modelling of vegetation, involved in biomass or surface moisture estimation at large scale, very high resolution polarimetric SAR acquisition on representative vegetated area could be useful. At resolution close to the wavelength such as 4 cm at X-band, the different scattering mechanisms can be spatially resolved. Several recent airborne radars have the capability of acquiring such very high resolution images, however direct acquisition of full polarimetric images at this resolution still is beyond the current capacity of our system. Since the need is for only a few such measures, repeat-pass acquisition might be an option. The issue is how to combine several lower resolution and/or partial polarimetric acquisitions into a full resolution full polarimetric synthetic image. Several modes are proposed and evaluated using opportunistic repeat-pass acquisitions with simultaneous full-polar and (partial polar) across-track interferometry.