We present a fast, memory efficient, linear time algorithm that generates a manifold triangular mesh passing through a set of unorganized points. Nothing is assumed about the geometry, topology or presence of boundaries in the data set except that ¡ is sampled from a real manifold surface. The speed of our algorithm is derived from a projection-based approach we use to determine the incident faces on a point. Our algorithm has successfully reconstructed the surfaces of unorganized point clouds of sizes varying from 10,000 to 100,000 in about 3-30 seconds on a 250 MHz, R10000 SGI Onyx2. Our technique is especially suitable for height fields like terrain and range scan data even in the presence of noise. We have successfully generated meshes for scan data of size 900,000 points in less than 40 seconds.