Bidirectional matching(BM) is an effective technique for area-based binocular stereo vision for maintaining one-toone correspondence, detecting half-occlusions and discarding false matches. This paper presents an extension of BM to trinocular stereo vision and proposes its memoryefficient implementation that maintains locality of memory access and thus enables the use of SIMD instruction sets of CPU for high time-performance. By using this scheme together with several other implementation techniques, 50fps throughput in generating disparity maps of approx. 320 ? 240 sizes has been attained with ordinary PC workstations.