AT HIS BEST , documentarian Nic Hill works a bit like a visual version of DJ Shadow. Just as Shadow worshipfully assembles soul and hip-hop fragments into his own compositions, Hill combines the imagery of hundreds of graffiti artists in tracing the form's local manifestations. The result is Piece by Piece, a thorough history that still makes time – especially just before it examines present-day law enforcement battles – for abstract, lyrical flowing passages.

Hill divides his movie into a trio of chapters. The first looks at San Francisco graffiti's cholo tag beginnings, the emergence of traditional funk and new wave styles, and the influence of the PBS doc Style Wars, while also making time for quick looks at artists like the late Dream One and sites like the now dormant Psycho City. The second section surveys the post-'89 quake surge of graffiti in vacant lots and pits, and formal shifts from letters to images. Chapter three dives into the fallout from the wretched Proposition 21, which made graffiti a felonious act. Throughout, Hill integrates local newspaper and television coverage that – aside from reporting by the Bay Guardian's A.C. Thompson – is often humorously clueless. (A San Francisco Chronicle piece refers to the "horrors of graffiti," for example.)

Many small elements of Piece by Piece could open up into larger movies – the poignant section devoted to Tie One is fleeting, forays by Twist and others from the streets into the "legit" art world go unexplored, and it would be great to see more about Reminisce, the female artist whose horses roamed wild through underpasses in the '90s. But Hill has succeeded at a mighty task. A former student of 2005 Goldie winner Melinda Stone, he shares her commitment to a deep but entertaining understanding of the city as both a historical site and a nexus for contemporary change. The past year or two has seen a small wave of graffiti features, and this one just might be the best. (Johnny Ray Huston)

'Piece by Piece' plays Thurs/8-Mon/12 (Thurs.-Fri. and Mon., 7:15 and 9:15 p.m.; Sat.-Sun., 2, 4, 7:15, and 9:15 p.m.), Red Vic Movie House, 1727 Haight, SF. $4-$8. (415) 668-3994.