The image showed children strolling past the scene apparently unaware of what was unfolding.
Martin was said to have been drinking at the time of both incidents.
Martin, of no fixed address, had denied two charges of outraging public decency and one each of common assault and using abusive language against a paramedic on the same day.
But today, Martin, of Grays, was convicted of all charges. She is due to be sentenced on Thursday, August 25.