These pages show 3d scatter plots of federal lawmakers' voting records based on political scorecards by the League of Conservation Voters, Peace Action, Democracy Scorecard (Common Cause) and Freedomworks (negated). One surprise is that according to Democracy Scorecard, Bernie Sanders' score isn't so high.
3D Visualization of U.S. Senators based on voting records (with freedomworks data). 3D Visualization of U.S. Senators based on voting records (with Peace Action data). 3D Visualization of U.S. House members based on voting records (partial data)