[en] Determining the direction of a gravitational wave (GW) source is necessary for confrontations between a candidate GW signal and its electromagnetic counterpart. In the context of low latency pipelines it is assumed that analytic solutions (based on the GW matrix reconstruction) can efficiently provide the GW direction. However, we identified that such analytic solutions present theoretical and practical limitations (indeterminacies) which were not previously mentioned in the literature. Under realistic conditions, we identified that for certain incoming directions, such solutions are unable to recover them. Therefore, we provide here for the first time a full review of these indeterminacy cases and explain their origins. We then propose a mathematical procedure that reduces such indeterminacies. Taking into account the constraining requirements of a low latency pipeline, we developed a method that requires the least computational power to retrieve GW directions. The mathematical considerations and method principle can be applied to any system of detectors able to reconstruct the GW matrix. We tested it on simulated data of the Schenberg GW detector. The results show that this method cancels out indeterminacies and the direction resolution $\mathrm{\sigma <!--\; ??\; -->}(\mathrm{\delta <!--\; ??\; -->}s)$ is limited by a 1/SNR law for any incoming direction. Thus it retrieves a remarkable advantage of the spherical GW antenna: the possibility of an isotropic direction determination. (paper)