Interval arithmetic has been used to create guaranteed intersection tests in the ray tracing algorithms. Although those algorithms improve the reliability in the visualization of implicit surfaces, they do not provide an alternative to avoid point sampling inside the pixel. In this paper, we develop an interval adaptive antialiasing algorithm (IAA) by means of the study of the coherence of sets of rays crossing a pixel (instead of individual rays) in order to detect variations over the hit surface. This method allows us to obtain better visualizations than the traditional interval ray tracing algorithms.